Wednesday, July 09, 2008

Type-safe Builder Pattern in Scala

The Builder Pattern is an increasingly popular idiom for object creation. Traditionally, one of it's shortcomings in relation to simple constructors is that clients can try to build incomplete objects, by omitting mandatory parameters, and that error will only show up in runtime. I'll show how to make this verification statically in Scala.


So, let's say you want to order a shot of scotch. You'll need to ask for a few things: the brand of the whiskey, how it should be prepared (neat, on the rocks or with water) and if you want it doubled. Unless, of course, you are a pretentious snob, in that case you'll probably also ask for a specific kind of glass, brand and temperature of the water and who knows what else. Limiting the snobbery to the kind of glass, here is one way to represent the order in scala.
sealed abstract class Preparation  /* This is one way of coding enum-like things in scala */
case object Neat extends Preparation
case object OnTheRocks extends Preparation
case object WithWater extends Preparation

sealed abstract class Glass
case object Short extends Glass
case object Tall extends Glass
case object Tulip extends Glass

case class OrderOfScotch(val brand:String, val mode:Preparation, val isDouble:Boolean, val glass:Option[Glass])

A client can instantiate their orders like this:
val normal = new OrderOfScotch("Bobby Runner", OnTheRocks, false, None)
val snooty = new OrderOfScotch("Glenfoobar", WithWater, false, Option(Tulip));

Note that if the client doesn't want to specify the glass he can pass None as an argument, since the parameter was declared as Option[Glass]. This isn't so bad, but it can get annoying to remember the position of each argument, specially if many are optional. There are two traditional ways to circumvent this problem — define telescoping constructors or set the values post-instantiation with accessors — but both idioms have their shortcomings. Recently, in Java circles, it has become popular to use a variant of the GoF Builder pattern. So popular that it is Item 2 in the second edition of Joshua Bloch's Effective Java. A Java-ish implementation in Scala would be something like this:
class ScotchBuilder {
private var theBrand:Option[String] = None
private var theMode:Option[Preparation] = None
private var theDoubleStatus:Option[Boolean] = None
private var theGlass:Option[Glass] = None

def withBrand(b:Brand) = {theBrand = Some(b); this} /* returning this to enable method chaining. */
def withMode(p:Preparation) = {theMode = Some(p); this}
def isDouble(b:Boolean) = {theDoubleStatus = some(b); this}
def withGlass(g:Glass) = {theGlass = Some(g); this}

def build() = new OrderOfScotch(theBrand.get, theMode.get, theDoubleStatus.get, theGlass);
}

This is almost self-explanatory, the only caveat is that verifying the presence of non-optional parameters (everything but the glass) is done by the Option.get method. If a field is still None, an exception will be thrown. Keep this in mind, we'll come back to it later.

The var keyword prefixing the fields means that they are mutable references. Indeed, we mutate them in each of the building methods. We can make it more functional in the traditional way:
object BuilderPattern {
class ScotchBuilder(theBrand:Option[String], theMode:Option[Preparation], theDoubleStatus:Option[Boolean], theGlass:Option[Glass]) {
def withBrand(b:String) = new ScotchBuilder(Some(b), theMode, theDoubleStatus, theGlass)
def withMode(p:Preparation) = new ScotchBuilder(theBrand, Some(p), theDoubleStatus, theGlass)
def isDouble(b:Boolean) = new ScotchBuilder(theBrand, theMode, Some(b), theGlass)
def withGlass(g:Glass) = new ScotchBuilder(theBrand, theMode, theDoubleStatus, Some(g))

def build() = new OrderOfScotch(theBrand.get, theMode.get, theDoubleStatus.get, theGlass);
}

def builder = new ScotchBuilder(None, None, None, None)
}

The scotch builder is now enclosed in an object, this is standard practice in Scala to isolate modules. In this enclosing object we also find a factory method for the builder, which should be called like so:
import BuilderPattern._

val order = builder withBrand("Takes") isDouble(true) withGlass(Tall) withMode(OnTheRocks) build()

Looking back at the ScotchBuilder class and it's implementation, it might seem that we just moved the huge constructor mess from one place (clients) to another (the builder). And yes, that is exactly what we did. I guess that is the very definition of encapsulation, sweeping the dirt under the rug and keeping the rug well hidden. On the other hand, we haven't gained all the much from this "functionalization" of our builder; the main failure mode is still present. That is, having clients forget to set mandatory information, which is a particular concern since we obviously can't fully trust the sobriety of said clients*. Ideally the type system would prevent this problem, refusing to typecheck a call to build() when any of the non-optional fields aren't set. That's what we are going to do now.

One technique, which is very common in Java fluent interfaces, would be to write an interface for each intermediate state containing only applicable methods. So we would begin with an interface VoidBuilder having all our withFoo() methods but no build() method, and a call to, say, withMode() would return another interface (maybe BuilderWithMode), and so on, until we call the last withBar() for a mandatory Bar, which would return an interface that finally has the build() method. This technique works, but it requires a metric buttload of code — for n mandatory fields 2n interfaces should be created. This could be automated via code generation, but there is no need for such heroic efforts, we can make the typesystem work in our favor by applying some generics magic. First, we define two abstract classes:
abstract class TRUE
abstract class FALSE

Then, for each mandatory field, we add to our builder a generic parameter:
class ScotchBuilder[HB, HM, HD](val theBrand:Option[String], val theMode:Option[Preparation], val theDoubleStatus:Option[Boolean], val theGlass:Option[Glass]) {

/* ... body of the scotch builder .... */

}

Next, have each withFoo method pass ScotchBuilder's type parameters as type arguments to the builders they return. But, and here is where the magic happens, there is a twist on the methods for mandatory parameters: they should, for their respective generic parameters, pass instead TRUE:
class ScotchBuilder[HB, HM, HD](val theBrand:Option[String], val theMode:Option[Preparation], val theDoubleStatus:Option[Boolean], val theGlass:Option[Glass]) {
def withBrand(b:String) =
new ScotchBuilder[TRUE, HM, HD](Some(b), theMode, theDoubleStatus, theGlass)

def withMode(p:Preparation) =
new ScotchBuilder[HB, TRUE, HD](theBrand, Some(p), theDoubleStatus, theGlass)

def isDouble(b:Boolean) =
new ScotchBuilder[HB, HM, TRUE](theBrand, theMode, Some(b), theGlass)

def withGlass(g:Glass) =
new ScotchBuilder[HB, HM, HD](theBrand, theMode, theDoubleStatus, Some(g))
}

The second part of the magic act is to apply the world famous pimp-my-library idiom and move the build() method to an implicitly created class, which will be anonymous for the sake of simplicity:
implicit def enableBuild(builder:ScotchBuilder[TRUE, TRUE, TRUE]) = new {
def build() =
new OrderOfScotch(builder.theBrand.get, builder.theMode.get, builder.theDoubleStatus.get, builder.theGlass);
}

Note the type of the parameter for this implicit method: ScotchBuilder[TRUE, TRUE, TRUE]. This is the point where we "declare" that we can only build an object if all the mandatory parameters are specified. And it really works:
scala> builder withBrand("hi") isDouble(false) withGlass(Tall) withMode(Neat) build()
res5: BuilderPattern.OrderOfScotch = OrderOfScotch(hi,Neat,false,Some(Tall))

scala> builder withBrand("hi") isDouble(false) withGlass(Tall) build()
<console>:9: error: value build is not a member of BuilderPattern.ScotchBuilder[BuilderPattern.TRUE,BuilderPattern.FALSE,BuilderPattern.TRUE]
builder withBrand("hi") isDouble(false) withGlass(Tall) build()

So, we achieved our goal (see the full listing below). If you are worried about the enormous parameter lists inside the builder, I've posted here an alternative implementation with abstract members instead. It is more verbose, but also cleaner.

Now, remember those abstract classes TRUE and FALSE? We never did subclass or instantiate them at any point. If I'm not mistaken, this is an idiom named Phantom Types, commonly used in the ML family of programming languages. Even though this application of phantom types is fairly trivial, we can glimpse at the power of the mechanism. We have, in fact, codified all 2n states (one for each combination of mandatory fields) as types. ScotchBuilder's subtyping relation forms a lattice structure and the enableBuild() implicit method requires the supremum of the poset (namely, ScotchBuilder[TRUE, TRUE, TRUE]). If the domain requires, we could specify any other point in the lattice — say we can doll-out a dose of any cheap whiskey if the brand is not given, this point is represented by ScotchBuilder[_, TRUE, TRUE]. And we can even escape the lattice structure by using Scala inheritance. Of course, I didn't invent any of this; the idea came to me in this article by Matthew Fluet and Riccardo Pucella, where they use phantom types to encode subtyping in a language that lacks it.



object BuilderPattern {
sealed abstract class Preparation
case object Neat extends Preparation
case object OnTheRocks extends Preparation
case object WithWater extends Preparation

sealed abstract class Glass
case object Short extends Glass
case object Tall extends Glass
case object Tulip extends Glass

case class OrderOfScotch(val brand:String, val mode:Preparation, val isDouble:Boolean, val glass:Option[Glass])

abstract class TRUE
abstract class FALSE

class ScotchBuilder
[HB, HM, HD]
(val theBrand:Option[String], val theMode:Option[Preparation], val theDoubleStatus:Option[Boolean], val theGlass:Option[Glass]) {
def withBrand(b:String) =
new ScotchBuilder[TRUE, HM, HD](Some(b), theMode, theDoubleStatus, theGlass)

def withMode(p:Preparation) =
new ScotchBuilder[HB, TRUE, HD](theBrand, Some(p), theDoubleStatus, theGlass)

def isDouble(b:Boolean) =
new ScotchBuilder[HB, HM, TRUE](theBrand, theMode, Some(b), theGlass)

def withGlass(g:Glass) = new ScotchBuilder[HB, HM, HD](theBrand, theMode, theDoubleStatus, Some(g))
}

implicit def enableBuild(builder:ScotchBuilder[TRUE, TRUE, TRUE]) = new {
def build() =
new OrderOfScotch(builder.theBrand.get, builder.theMode.get, builder.theDoubleStatus.get, builder.theGlass);
}

def builder = new ScotchBuilder[FALSE, FALSE, FALSE](None, None, None, None)
}



* Did you hear that noise? It's the sound of my metaphor shattering into a million pieces



EDIT 2008-07-09 at 19h00min: Added introductory paragraph.

457 comments:

«Oldest   ‹Older   201 – 400 of 457   Newer›   Newest»
Unknown said...

פוסט מרענן במיוחד. לגמרי משתף.
ברוקר לי

Chiến NHX said...

ok anhi

máy xông tinh dầu phun sương bottle cap

may xong phong ngu

may xong huong

may phun suong nao tot

Kamal S said...

Excellent explanation of how to create objects in Scala. You've made the concept easily understandable through your scotch example. As always, great content. Looking forward to your next blog.

Mobile App Development Company in Chennai

Dogma said...

כתיבה מעולה, אהבתי. אשתף עם העוקבים שלי.
מציאות רבודה

Ben Johnson said...

Thanks for Sharing...Nicely Written Blog...

Artificial Intelligence Training in Chennai
Best Artificial Intelligence Training in Chennai BITA Academy
artificial Intelligence certification training in chennai
artificial Intelligence training institutes in chennai
artificial Intelligence course in chennai
artificial Intelligence training course in chennai
artificial Intelligence course in chennai with placement
artificial Intelligence course fees in chennai
AI Training in Chennai
artificial Intelligence training in omr
artificial Intelligence training in velachery
Best artificial Intelligence course fees in chennai
artificial Intelligence course in omr
artificial Intelligence course in velachery
Best artificial Intelligence course in chennai

How To Asset Manage said...

Thanks for sharing the info
global asset management seoul

Global Asset Management Udemy said...

Thank you for sharing.
global asset management

svrtechnologies said...

Thanks for sharing such an useful and informative stuff...

Selenium Testing Training
Selenium Tutorials

Babas Judi said...

I am glad to be one of several visitants on this outstanding internet site (:, appreciate it for posting . https://royalcbd.com/cbd-legal-status/

Babas Judi said...

I am glad to be one of several visitants on this outstanding internet site (:, appreciate it for posting . https://royalcbd.com/cbd-legal-status/

Indhu said...

thanks for sharing this informations.
Selenium Training in Coimbatore

Software Testing Course in Coimbatore

python training institute in coimbatore

data science training in coimbatore

android training institutes in coimbatore

ios training in coimbatore

aws training in coimbatore

all bank csp said...

Thanks for sharing this articles
all bank csp
csp registration
sbi csp registration
digital csp registration

saran said...

I went through your blog its really interesting and holds an informative content. Thanks for uploading such a wonderful blog
Digital Marketing Training Course in Chennai | Digital Marketing Training Course in Anna Nagar | Digital Marketing Training Course in OMR | Digital Marketing Training Course in Porur | Digital Marketing Training Course in Tambaram | Digital Marketing Training Course in Velachery

Tekniko Global said...
This comment has been removed by the author.
사설토토 said...

תמשיכו בפרסום פוסטים מעניינים כמו זה. תודה.
תמונות על קנבס

intercom4u said...

Thank you for sharing information.
אינטרקום עם מצלמה

python coaching said...

Python Training in Coimbatore

Python course in Coimbatore
Python Classes in Coimbatore
Python Training Institute in Coimbatore

Java Training in Coimbatore

Java course in Coimbatore
Java Classes in Coimbatore
Java Training Institute in Coimbatore

Digital Marketing Training in Coimbatore

Digital Marketing course in Coimbatore

Machine Learning Training in Coimbatore

Machine Learning course in Coimbatore


Datascience course in Coimbatore
Datascience training in Coimbatore
internship training in Coimbatore
internship in Coimbatore
inplant training in Coimbatore

Fixadoor said...

Thanks for sharing with us.
Garage door repair Scarborough

Clark said...

awesome post.
Global asset management Seoul

Instagram Followers USA said...

thanks for sharing nice article. Most of users buying location based real and active instagram services Buy Instagram Followers USA

Buy Mumbai Instagram followers said...

Such a Great article, because lots of key point you shared and that is very helpful. I found best site to Buy Mumbai Instagram followers to increase real and active audience from targeted location. More details to Contact us + 917339876756

sudhan said...

Great Article… I love to read your articles because your writing style is too good, its is very very helpful for all of us and I never get bored while reading your article because, they are becomes a more and more interesting from the starting lines until the end.


Robotic Process Automation (RPA) Training in Chennai | Robotic Process Automation (RPA) Training in anna nagar | Robotic Process Automation (RPA) Training in omr | Robotic Process Automation (RPA) Training in porur | Robotic Process Automation (RPA) Training in tambaram | Robotic Process Automation (RPA) Training in velachery

Anonymous said...

Thanks for sharing this well crafte content website with us. Webstie design agecny faridabad, Website Designing Company in Gurgaon, Ecommerce Web Development Services , Results Focused SEO Agency

kenwood said...

They are not engineers that create products or write algorithms. Often, companies look for Unicorn like professionals who are good at statistics and experienced in industry domains like financial services for best machine learning course in hyderabad

แทงบอลออนไลน์ said...

thanks for sharing this with us.
UFABET

Stratford Management said...

useful information.
stratford management Tokyo

Petersons said...

I am really very agree with your qualities it is very helpful for look like home. Thanks so much for info and keep it up.


Bastion Balance Korea

American Male Wellness said...

Very useful info.
Hormone replacement Las Vegas

Data Science Training said...

You completely match our expectation and the variety of our information.

Data Science Training

bill.wood said...

In a simple way, it also termed as the promotional approach for various products or services via the internet or electronic media. digital marketing training in hyderabad

abid said...

Thank you for helping people get the information they need. Great stuff as usual. Keep up the great work!!!
about us

Garage Door Pros Ontario said...

Thanks for a wonderful share.
Garage Door Repair Kanata

a1garagedoors said...

Thanks for posting an informative information
a1garagedoors.ca

digital marketing training in hyderabad said...

In a simple way, it also termed as the promotional approach for various products or services via the internet or electronic media.
digital marketing training in hyderabad

Petersons said...

חייב להחמיא על הכתיבה. מאמר מצוין.

בריכות שחיה פיברגלס

Entertaining Game Channel said...

This is Very very nice article. Everyone should read. Thanks for sharing. Don't miss WORLD'S BEST GAME FOR GameDownload

Petersons said...

If you could message me with any hints & tips on how you made your blog look this cool, I would be appreciative!


Garage Door Repair Strathmore

Garage Door Pros Ontario said...

very informative and helpful for me.
garagedoorpitt.com

Event Management services in chennai said...

I'm appreciate your writing skill.Please keep on working hard
Event Management services in chennai
Catering Manpowers in chennai
Male and Female Promoters in chennai
Wedding Event Management Companies In Chennai
Event staffing services Chennai

euro cars said...

מעניין מאוד, למרות שלא הכל מדויק לדעתי
https://eurocars.co.il/

Yours Home Tutor said...

This article is very helpful. keep it up. I find it very helpful. this Blog is very informative & Knowledgeable.
Home tutor in Delhi

euro cars said...

אם כי אני לא מסכים עם כל מה שנכתב, מאמר מעניין
https://www.sedrismile.co.il

James said...

keep it up.
garage door spring replacement ottawa

James said...

Thanks for posting.
Garage Door Opener Repair Oshawa

James said...

Thanks for your great post
Overhead Door Repair Summerside

James said...

Thank you very much for such an interesting post.
Guys Fix It Mag

R ADK said...

Drilling consultants
edumeet | python training in chennai
Organic Chemistry tutor

Amlida James said...

Hi,

Thank for sharing such a nice post on your blog keep it up and share more on your blog.

best firewall devices to protect your home network

Petersons said...

I was searching for that post quick a long time... fortunately I found it on right time...Thanks again for sharing


dishwasher repair mississauga

Home Improvement said...

Hi,

Thank for sharing such a nice post on your blog keep it up and share more.

Free Crack Software Download

James said...

More impressive Blog
garage door repair chestermere

Petersons said...

If you could message me with any hints & tips on how you made your blog look this cool, I would be appreciative!


vancoverheadoors.ca

Orthocure Healthcare said...

Physiotherapy and chiropractic treatment is a huge part of knee pain treatment procedures. High-quality foot insoles help in correcting foot alignment which reduces and alleviates foot pain.

Micky said...

I really appreciate such a post.
UFABET

siva said...

The information given in this article is very good and I like it. I have also written this kind of blog you can also read for more knowledge.
why cloud computing is needed
benefits of machine learning
benefits of devops
php vs .net
js interview questions
javascript interview questions for experienced

kirankumarpaita said...

software testing company in India
software testing company in Hyderabad
Really nice post.
Thanks for sharing such an amazing information with us.
keep sharing.

Micky said...

แทงบอล

Micky said...

Wow! Thanks for sharing your inspiring ideas.
UFABET

Petersons said...

thanks… I’ve been bookmarking them for a while now and just decided to create a post to provide them to others…


Garage Door Repair Doctors

Micky said...

Thanks for the information.
ไพ่บาคาร่า royal

360digiTMG Training said...

This is really a nice and informative, containing all information and also has a great impact on the new technology. Thanks for sharing it,
Best Data Science Courses in Hyderabad

Petersons said...

Its wonderful, looking at the time and effort you put into your weblog and detailed information you provide. I'll bookmark your weblog and visit it weekly for your new posts.


Los Angeles Garage Door Repair

Petersons said...

I am not much into reading, but somehow I got to read lots of articles on your blog. Its amazing how interesting it is for me to visit you very often.


Garage Door Cable Repair

Home Improvement said...

Thank you for sharing the post. promo codes

Petersons said...

מרתק כמה שלא הבנתי כלום עד שקראתי את המאמר הנפלא הזה

נכס מסחרי מניב למכירה

Petersons said...

לא כל כך מסכים עם הכל כאן האמת.

התקנת אינטרקום

Cubestech said...

WOW! Many thanks for keeping your content up to date. Your level of dedication is clearly visible through this blog!

Cheers!!

"Best mobile app development service in chennai
Best ERP software solutions in chennai
Digital Marketing Agency in Chennai
Best web development company in chennai
"

Petersons said...

Its wonderful, looking at the time and effort you put into your weblog and detailed information you provide. I'll bookmark your weblog and visit it weekly for your new posts.


silvergaragedoors.ca

Petersons said...

I am not much into reading, but somehow I got to read lots of articles on your blog. Its amazing how interesting it is for me to visit you very often.


garage door repair east edmonton

Unknown said...

Nice blog...!!! Really so good post, I like your unique post and I gladly waiting for your new post...

Web Development Company in Haldwani

Unknown said...

I have inspected your blog its associating with and essential. I like it your blog.
Web Development Company in Haldwani

Rakesh said...

I like this post and there is obviously a lot to know about this. I think you made some good points in Features also i figure that they having a great time to peruse this post. They might take a decent site to make an information, thanks for sharing it to me Keep working, great job!
Braces in Bangalore

Professional Course said...

Very good message. I stumbled across your blog and wanted to say that I really enjoyed reading your articles. Anyway, I will subscribe to your feed and hope you post again soon.

Business Analytics Course

Petersons said...

Thanks for the update you have nicely covered this topic. keep it up


Gloss Garage Doors

360DigiTMGNoida said...

This Blog is very useful and informative.
data scientist course in noida

360digitmgdelhi said...

I read that Post and got it fine and informative. Please share more like that...
data science course delhi

stock market expert in delhi said...

Lakshay consultant is known for giving best services to there clients with full of honesty and dignity . Lakshay consultancy deals in Equities, Currencies, Commodities, IPOs, Stock Market Expert in Delhi , Bonds/NCDs through NSE, BSE, MCXSX, USE. Depository services through NSDL and CDSL.

arshiya said...

I enjoyed reading your article. Thanks for taking the time to post such a valuable article.
seo content writing tips
language similar to english
salesforce basics
star certification
hacking books
interview questions on tableau

Rick said...

Excellent, and thanks for sharing this.

Rick Anderson

Petersons said...

Cool blog you got here and thank you for the valuable info.


garage door repair

360DigiTMG said...

This is a great motivational article. In fact, I am happy with your good work. They publish very supportive data, really. Continue. Continue blogging. Hope you explore your next post
data scientist malaysia

Petersons said...

This is really great news. Thank you for sharing it with us!


garage door blog

Micky john said...

Your service is really cool.
e-learning

Petersons said...

This is a brilliant writing and very pleased to find this site. I couldn’t discover to much different information on your blog. I will surely be back again to look at some other important posts that you have in future.


garage door repair Guelph

Nictcspbc said...


Thank you for sharing such a great information. Here NICTCSPBC is the best service provider of SBI Kiosk Banking in India which provides the best services of Kiosk Banking at reliable prices to their customers.

Csp registration
Csp apply

Unknown said...

You got a really useful blog I have been here reading for about half an hour. I am a newbie and your post is valuable for me.


garage door repair Scarborough 

madhu said...

Single drum will only provide washing process and dual drum will provide the washing process along with draining function. Whirlpool Washing machine Service Center in ChemburThe single drum will occupies very less space to store comparing to double drum washing machines the new clothes washers are updated with many progressed washing highlights. Whirlpool Washing Machine Service Center in Mira RoadThe utilization of the climate control systems are mostly increments in summer seasons. Whirlpool Washing machine Service Center in KandivaliSince climate control systems are use for take just cool air. What's more, these forced air systems can run for quite a long time with no issue and this

madhu said...

Subterranean insect sort of issue they will tackier of it they have colossal information to take care of the issue. Whirlpool Refrigerator Service Center in MankhurdFurthermore, we are giving best proposals to you on month general assistance guarantee and multi month service guarantee to your items. Whirlpool Refrigerator Service Center in Vashi We are giving every minute of every day hour’s service to the clients. Best help and poor clients will fulfill with our service. Whirlpool Refrigerator Service Center in Churchgate One of the best services to the customers. Our supervisory group has over 10 years of involvement service suppliers; we are consistently offers the best types of assistance to the customers. Whirlpool Refrigerator Service Center in Marine LinesWith the best specialized unit we help to tackle the any major and minor fixes in the item. And we take the all safety measures of covid-19. And our technicians will give to you best services to your products.

Michael Oliver said...

Good post,

Digital Marketing Companies in Chennai, Website Design Companies in Chennai, SEO Companies in Chennai, Digital Marketing Company Chennai, Web Design Company Chennai.

https://www.wisewebtek.com

Petersons said...

חשבתי שאתקל בסתם עוד מאמר שטחי. כמובן שטעיתי.

פוליש קריסטל

Micky john said...

Good post. Thank you for sharing this with us.
News For Finance

Nisha said...

Website Development Services In Delhi
Web Cloud Technology offers world class web development services in Delhi, India. We promise to take care of all your website development needs by providing high end and modern solutions that are inventive and profitable.

For more information visit on:-
https://webcloudtechnologies.com/

David Smith said...

Good writing...keep posting dear friend

אטרקציות לבר מצווה

Data Science Institute Bangalore said...

It's very educational and well-written content for a change. It's good to see that some people still understand how to write a great article!
Data Science Institute in Bangalore

Data Analytics Courses in Bangalore said...

This is just the information I find everywhere. Thank you for your blog, I just subscribed to your blog. It's a good blog.

Data Analytics Courses in Bangalore

Data Science in Pune said...

You can comment on the blog ordering system. You should discuss, it's splendid. Auditing your blog would increase the number of visitors. I was very happy to find this site. Thank you...

Data Science Classes in Pune

Unknown said...

אני לא מסכים עם כל מה שכתוב, אבל מאמר מעניין מאוד

דוכני מזון לאירועים 

Data Analytics Courses in Bangalore said...

Very good message. I stumbled across your blog and wanted to say that I really enjoyed reading your articles. Anyway, I will subscribe to your feed and hope you post again soon.

Data Analytics Courses in Bangalore

Data Science in Pune said...

I enjoyed the coursework, the presentations, the classmates and the teachers. And because my company reimbursed 100% of the tuition, the only cost I had to pay on my own was for books and supplies. Otherwise, I received a free master's degree. All I had to invest was my time.
Data Science Training in Pune

Jack Harry said...

Nice content
greenairductcleaningpittsburgh.com

Unknown said...

I was very pleased to find this site.I wanted to thank you for this great read!! I definitely enjoying every little bit of it and I have you bookmarked to check out new stuff you post.


commercial hood cleaning pittsburgh 

David Smith said...

This is a really good read for me, Must admit that you are one of the best bloggers I ever saw.Thanks for posting this informative article.

garage door repair in Evergreen

Jack Harry said...

This amazing post impressed me
garage door repair in pittsburgh

Business said...

Nice Information. Thanks for sharing. Reach us For the same,
WEB Technologies,
IMAGE Editing Services,
LEATHER Products.

Micky john said...

informative post
garage door installation burlington

Micky john said...

This amazing post impressed me
Cleveland Plumbing Guy

Data Analytics Courses in Bangalore said...

You actually make it seem like it's really easy with your acting, but I think it's something I think I would never understand. I find that too complicated and extremely broad. I look forward to your next message. I'll try to figure it out!
Data Analytics Courses in Bangalore

Data Science in Bangalore said...

Very informative message! There is so much information here that can help any business get started with a successful social media campaign!
Data Science In Bangalore

Micky john said...

It is very fantastic article , Thanks for sharing .
best essay writing service reddit

Data Science Institute Bangalore said...

I was very happy to find this site. I wanted to thank you for this excellent reading !! I really enjoy every part and have bookmarked you to see the new things you post.

Data Science Institute in Bangalore

Data Science Institute Bangalore said...

I am very happy to have seen your website and hope you have so many entertaining times reading here. Thanks again for all the details.
Data Science Institute in Bangalore

Micky john said...

It's always exciting to read articles from other writers and practice something from their websites.
Green Air Duct Cleaning

Micky john said...

חשבתי שאתקל בסתם עוד מאמר שטחי. כמובן שטעיתי.
פיתוח אפליקציות לאנדרואיד

Indo Routes said...

Hey, I like this and its helpful for me and i appreciate your work. Thanks for sharing nice info. Golden Triangle Tour Package India

Indo Routes said...

Thanks for sharing the info, keep up the good work going.... I really enjoyed exploring your site. Golden Triangle Tour Package India

SNK Social Fame said...

I am so happy to have found your blog! Your article looks beautiful! The information you have shared is very informative. thanks Buy Instagram Followers India

vé máy bay từ canada về Việt Nam said...

Aivivu đại lý vé máy bay, tham khảo

vé máy bay đi Mỹ bao nhiêu tiền

mua vé máy bay từ hàn quốc về việt nam

vé bay nha trang sai gon

vé máy bay phú quốc hà nội

vé máy bay eva từ mỹ về việt nam

Data Science Institute Bangalore said...

It's like you understand the topic well, but forgot to include your readers. Maybe you should think about it from several angles.
Data Science Certification in Bangalore

Data Science in Pune said...

It fully emerged to crown Singapore's southern shores and has undoubtedly put it on the world residential monument map. Still, I scored more points than I have in one season for GS. I think it would be hard to find someone with the same consistency that I have had over the years, so I'm happy.
Data Course Training in Pune

Best Data Science Courses in Bangalore said...

Now is the perfect time to plan for the future and now is the time to be happy. I have read this article and if I can I would like to suggest some cool tips or advice. Perhaps you could write future articles that reference this article. I want to know more!
Best Data Science Courses in Bangalore

Data Science in Pune said...

I am sure it will help many people. Keep up the good work. It's very compelling and I enjoyed browsing the entire blog.
Data Science Course in Pune

Data Analytics Course in Bangalore said...

A good blog always contains new and exciting information and as I read it I felt that this blog really has all of these qualities that make a blog.
Data Analytics Course in Bangalore

Data Science in Pune said...

I have voiced some of the posts on your website now, and I really like your blogging style. I added it to my list of favorite blogging sites and will be back soon ...
Data Science Training in Pune

vivikhapnoi said...

It's really amazing to have many lists of will help to make thanks a lot for sharing
vé máy bay vietjet đi phú yên

lich bay tu tphcm di singapore

săn vé 0 đồng đi thái lan 2020

vé máy bay giá rẻ đi malaysia

báo giá vé máy bay đi úc

vé máy bay đi hàn quốc jetstar

Data Analytics Course in Bangalore said...

They are produced by high level developers who will stand out for the creation of their polo dress. You will find Ron Lauren polo shirts in an exclusive range which includes private lessons for men and women.
Data Analytics Course in Bangalore

Data Analytics Course in Bangalore said...

You can comment on the blog ordering system. You should discuss, it's splendid. Auditing your blog would increase the number of visitors. I was very happy to find this site. Thank you...
Data Analytics Course in Bangalore

Best Data Science Courses in Bangalore said...

I bookmarked your website because this site contains valuable information. I am very satisfied with the quality and the presentation of the articles. Thank you so much for saving great things. I am very grateful for this site.
Best Data Science Courses in Bangalore

Data Analytics Course in Bangalore said...

I will be interested in more similar topics. I see you have some really very useful topics, I will always check your blog thank you.

Data Analytics Course in Bangalore

Micky said...

This is my first-time visit to your blog and I am very interested in the articles that you serve. Provide enough knowledge for me.
warehouse garage door repair in philadelphia

Herry said...

So lucky to come across your excellent blog. Your blog brings me a great deal of fun. Good luck with the site.
commercial window replacement

Digital Vishnu said...

This is incredibly useful information!! Excellent work. All is very fascinating to learn and simple to grasp. Thanks for sharing such great info. Keep Post These kinds of Articles in the future.

Digital Marketing Course in Coimbatore
Digital Marketing Course Training in Tirupur
Digital Marketing Course Training in Madurai
Digital Marketing Course Training in Theni
Digital Marketing Training in Coimbatore

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


Los Angeles Garage Doors

Business Analytics Course said...

It would also motivate almost everyone to save this webpage for their favorite helper to help get the look published.
Business Analytics Course

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


commercial garage door repair

Alvin Steve said...

This is a wonderful article, Given so much info in it, These type of articles keeps the user's interest in the website.
website cost

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


San Francisco Garage Door Repair

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


Window and Door Repair in Mississauga

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


garage door motor repair

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


central air conditioning

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


Kitchen Star Houston

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


commercial garage door repair

Petersons said...

I guess there's always an easier way ...


reputation management

Pradeep Appslure said...
This comment has been removed by the author.
360DigiTMGAurangabad said...

"Very Nice Blog!!!


Please have a look about "
data science courses aurangabad

360DigiTMGAurangabad said...

Wow, amazing post! Really engaging, thank you.
data scientist course in aurangabad

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


Baby shower game

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


Washing Machine Repair

Petersons said...

I wanted to thank you for this great read!! I definitely enjoying every little bit of it.I have you bookmarked to check out new stuff you post.


scam warning

Home Improvement said...

Great post I must say and thanks for the information. Education is definitely a sticky subject. However, is still among the leading topics of our time. I appreciate your post and look forward to more. Pareto Analysis

Petersons said...

חייב להחמיא על הכתיבה. מאמר מצוין.

פרגולה אלומיניום

Anonymous said...

Website Designing Agencies India

Anonymous said...

Anti Dripping Additives For Plastics

vivikhapnoi said...

Fascinating blog! Is your theme custom made or did you download it from somewhere?A theme like yours with a few simple tweeks would really make my blog jump out. Please let me know where you got your design. With thanks
ve may bay tu My ve Viet Nam

ve may bay tu han quoc ve viet nam

Vé máy bay giá rẻ tu Nhat Ban ve Viet Nam

vé máy bay từ singapore về hà nội vietjet

vé máy bay giá rẻ tu Dai Loan ve Viet Nam

chuyến bay nhân đạo từ canada về việt nam

Petersons said...

חייב להחמיא על הכתיבה. מאמר מצוין.

רעות מלכין עיצוב גבות

Petersons said...

I guess there's always an easier way ...


Roofing service in Columbus

Branzone Creative Design Agency said...

Nice Article. Branzone - Branding & Logo Design Company In Coimbatore

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


auto Locksmith

skvisiontec said...

thanks very nice article keep up the good work Rubber Calender Machine

Julli said...

It's always exciting to read articles from other writers and practice something from their websites.
Clear Water Management

Michael Oliver said...

Digital Marketing, Digital Marketing Online Training, Digital Marketing Training Programs, Women Entrepreneurship, Women Entrepreneurship Training Programs, Digital marketing online video course, Women Entrepreneurship Online Certification Course, Business coaching, Training for Business owners, Business coaching for women, young entrepreneurs training

https://www.eminentdigitalacademy.com/

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


Houston Garage Door 4 Business

Julli said...

I like this post, And I figure that they have a great time to peruse this post, they might take a decent site to make an information, thanks for sharing it with me.
24 Hour Locksmith

Julli said...

Thanks for the nice blog. It was very useful for me. I'm happy I found this blog. Milton Locksmith Pro

James said...

I was exactly searching for. Thanks for such a post and please keep it up. locksmith in Vaughns

IT Tutorials said...

It's Very informative and helpful. If you are interested in learning JMeter please refer to the link below. Thank you

JMeter Training in Chennai | JMeter Course in Chennai | JMeter Online Course

Petersons said...

Can you please provide more information on this subject? BTW your blog is great. Cheers.


etobicokecarlocksmith.com

Digital Marketing Course said...

I was browsing the internet for information and found your blog. I am impressed with the information you have on this blog.

Digital Marketing Course in Bangalore

Petersons said...

Can you please provide more information on this subject? BTW your blog is great. Cheers.


stratford management scam

James said...

I like this post, And I figure that they have a great time to peruse this post, they might take a decent site to make an information, thanks for sharing it with me. locksmith in Markham

Machine Learning Course in Bangalore said...

You actually make it seem like it's really easy with your acting, but I think it's something I think I would never understand. I find that too complicated and extremely broad. I look forward to your next message. I'll try to figure it out!

Machine Learning Course in Bangalore

Petersons said...

Very informative site, i must bookmark it, keep posting interesting articles...


transponder key programming

ITSolution4Us Cloud Training India said...

ITSolution4Us is a platform where curious and eager professionals/graduates can upskill. We do so by connecting you with Certified experts through online cloud training in various technologies. We provide a perfect amalgamation of theoretical knowledge and practical experience to help you take that plunge in various technologies, right from the get-go.
We offer VBCS Training and Oracle OIC training. You can also learn Microsoft Azure training, Mule soft training, Salesforce training, Amazon AWS Training etc.
IT Solution 4 us is a platform where curious and eager professionals/graduates can upskill. We do so by connecting you with certified experts through online training in various technologies.

Digital Marketing Course said...

I am more curious to take an interest in some of them. I hope you will provide more information on these topics in your next articles.

Digital Marketing Course in Bangalore

opbest said...

Took me time to read all the comments, but I really enjoyed the article. It proved to be Very helpful to me and I am sure to all the
commenters here! It’s always nice when you can not only be informed, but also entertained!

visit my blog:: 휴게텔

(freaky)

skvisiontec said...

You can also find our quickbooks help desk phone number for further details about how to contact our QuickBooks customer support team.

VISHYAT TECHNOLOGIES SEO INDIA said...

Vishyat Technologies is one of the best Digital Marketing and SEO company in Chandigarh. Our expert SEO services in Chandigarhhave helped a lot of business get better online exposure. SEO services Company in Amritsar,
Seo Company In Punjab, SEO company in India, SEO COMPANY IN GURGAON

Vishyat Technologies offers Website development, SEO, PPC, Backlink Building, Content Development, Content Marketing, Conversion Rate Optimization, Email Marketing, Online Reputation Management, SEO Company in Faridabad, SEO Company in Noida, Brand Reputation Management, Hospital Reputation Management, Web Analytics and Internet Marketing. Vishyat Technologies optimizes your site, withor set up an extensive social media presence for you. We offer great quality content for your website and effective social media marketing campaigns. We also offer SEO Reseller services or SEO Outsourcing services to our clients in US, UK, Australia, Canada and Middle-East. You can check how’s your keyword ranking using a Rank checker tool on our website.
VISHYAT PRESENCE
Our digital Marketing services and SEO services in Chandigarh enable us to take evidence based
strategic decisions. Getting website ranked on the first page of the SERP is the aim of every website
owner. However, this is a complex process as it involves the large numbers seo training in chandigarhof factors that need to be taken care of. So, what do we do? We focus on the core guidelines laid down by Google Webmasters like to have a unique content, schema.org validated code, positive link profile, etc.

ICFAD SKIN SPECIALIST DERABASSI said...

The Cosmetic Health Clinic provides a range of non-invasive cosmetic treatments designed to improve your skin & hair and restore its natural beauty. We have the best doctors for skin treatment in Derabassi or skin specialist in Derabassi. We also offer hairfall treatment in Derabassi. The transparency in the services that we offer and the honesty towards our work has made us one of the Facial aesthetics & Hair Transplant Clinic.

Fortune Education Group said...

thanks for this great post keep it up Danylo Halytsky Lviv National Medical University

360DigiTMGAurangabad said...

Amazing blog.Thanks for sharing such excellent information with us. keep sharing...
data scientist training in aurangabad

360DigiTMGAurangabad said...

This post is very simple to read and appreciate without leaving any details out. Great work!
data scientist training in aurangabad

Tutorials said...


Very informative and helpful. Thank You for sharing the blog.
JMeter training in chennai | JMeter course online

Fortune Education Group said...

thanks for this article Why Study MBBS at V.N.Karazin KNU?

Get It SMS said...

My brother recommended, I might like this web site. He was totally right. This put up actually made my day. You can not believe just how much time I had spent for this information! Thank you for sharing I believe a lot of people will be surprised to read this article. This article provides light by which we can notice the reality. This really is very nice one and allows advanced information. Get It SMS is a India No 1 bulk SMS Service provider. We are giving special offer in bulk SMS service. Our Services are Voice SMS, promotional bulk SMS, transactional SMS, miss call service, bulk e-mailing, transactional bulk SMS, Missed call alert Whatsapp SMS and website Design. Sign Up for a free trial!
Whatsapp Bulk SMS Service Provider Bangalore
Bulk SMS Service Provider in Bangalore
Bulk SMS Service Provider in Bangalore
Email Marketing Services in Bangalore, Gurugram, Jaipur, India

vishyat technologies said...

Vishyat Technologies is one of the best Digital Marketing and SEO company in Chandigarh. Our expert SEO services in Chandigarh have helped a lot of business get better online exposure. SEO services Company in Amritsar,
Seo Company In Punjab, SEO company in India, SEO COMPANY IN GURGAON

Vishyat Technologies offers Website development, SEO, PPC, Backlink Building, Content Development, Content Marketing, Conversion Rate Optimization, Email Marketing, Online Reputation Management, SEO Company in Faridabad, SEO Company in Noida, Brand Reputation Management, Hospital Reputation Management, Web Analytics and Internet Marketing.

BK-25 said...

Good blog thank you for sharing.

Robotic Process Automation Training in Chennai
PHP Training in Chennai
DevOps Training in Chennai
Cloud-Computing Training in Chennai
Best Software training institute
blueprism training in Chennai
Ui-Path Training in Chennai
Azure Training in Chennai

Professional Training Institute said...

Very good message. I came across your blog and wanted to tell you that I really enjoyed reading your articles.

Digital Marketing Course in Bangalore

BK-25 said...

Awesome blog thank you for sharing.

DevOps Certification in Chennai
php course in chenna
Software training institute in chennai
blue prism course in chennai
best rpa training in chennai
rpa uipath training in chennai
cloud computing courses in chennai
azure certification in chennai

Petersons said...

Our goal is to make buying or selling a home, or getting a mortgage, as easy and stress-free as possible. Our Artificial Intelligence-Digitized platform is designed to educate & empower the consumer and connect you with top-rated certified agents, while saving thousands of dollars through the process.

buy realty

Digital Vishnu said...

Thanks for sharing a great article. The Article which you have shared is very informative..

Digital Marketing Courses in Coimbatore
Digital Marketing Courses in Trichy
Digital Marketing Courses in Madurai

amirosta said...

در صورت نیاز به خدمات ساخت لوگو و آرم می توانید به آژانس ریوال آنلاین مراجعه کنید.

tech science said...



It is late to find this act. At least one should be familiar with the fact that such events exist. I agree with your blog and will come back to inspect it further in the future, so keep your performance going.machine learning course in jaipur

tech science said...


Hi, I looked at most of your posts. This article is probably where I got the most useful information for my research. Thanks for posting, we can find out more about this. Do you know of any other websites on this topic?ethical hacking training in jaipur

Credo Systemz said...

very interesting and informative article. Python Training in Chennai

Bhuvankumar said...


Thank you for sharing this wonderful blog, I read that Post and got it fine and informative. Please share more like that...
Ethical Hacking Institute in Bangalore

Education said...

Superb Information and really appreciated with it and this is fine to read and valuable. I like it.
Digital Marketing Course fees in Hyderabad

Nathan said...

I am here for the first time. I found this blog and found it really useful and it helped me a lot, thank you.
Data Analytics Training in Bangalore

Nathan said...

Very informative message! There is so much information here that can help me thank you for sharing.
Data Analytics Course in Lucknow

Professional Learning Institute said...

Very good message. I came across your blog and wanted to tell you that I really enjoyed reading your articles.

Data Science Course in Kolkata

Professional Learning Institute said...

It's like you've got the point right, but forgot to include your readers. Maybe you should think about it from different angles.

Data Science Training in Nashik

Career Courses Academy said...


Very informative message! There is so much information here that can help any business start a successful social media campaign!
Data Science Training in Nashik

«Oldest ‹Older   201 – 400 of 457   Newer› Newest»