Talk:Builder pattern: Difference between revisions

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==Why builders?==

Builders are an OOP pattern to construct complex objects without overloading a constructor. The important part is that you don’t need to call all of the steps to construct. You can call only those steps that are necessary for producing a particular configuration of an object. Also a `director` class helps the builder to construct a specific type of object. I'm missing these concepts in the article. [[User:Theking2|Theking2]] ([[User talk:Theking2|talk]]) 20:52, 25 November 2024 (UTC)

:This is helpful. I've read the wiki and it's still isn't entirely clear to me how or why I would use this. [[User:Jgoure|Jgoure]] ([[User talk:Jgoure|talk]]) 21:49, 7 April 2025 (UTC)

==Builders and immutable objects==

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A major benefit of builders is that they can be used to create immutable objects without complex constructors. In Java, the builder pattern also simulates named constructor parameters:

<sourcesyntaxhighlight lang="java">

public final class Pizza {

private final String dough;

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}

}

</syntaxhighlight>

</source>

==Abstract Builder class==

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This seems to say that the Builder manages "the correct sequence of object creation". Is the client the "Director" or is the builder the "Director"? <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[Special:Contributions/61.14.96.7|61.14.96.7]] ([[User talk:61.14.96.7|talk]]) 07:51, 30 April 2007 (UTC).</small><!-- HagermanBot Auto-Unsigned -->

:According to the UML, the client is the Director. And I believe the word "Director" should be replaced with "Client" for clarity and to avoid confusion since some people tend to think "Director" is a class which is part of the pattern. [[Special:Contributions/186.0.181.64|186.0.181.64]] ([[User talk:186.0.181.64|talk]]) 17:46, 10 April 2023 (UTC)

== Missing the Mark ==

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== Two example implementations ==

I'm not sure we need two example implementations. C++ and Java are not radically different in syntax, and there's nothing about the pattern that can't be covered in one. &mdash;&nbsp;[[User:Anndelion|<fontspan colorstyle="color:#6B8E23;">'''anndelion'''</fontspan>]]&nbsp;[[User_talk:Anndelion|<span style="font-size:125%; vertical-align:text-middle; color:#DAA520"><span class="Unicode">&#10059;</span></span>]] 21:40, 18 April 2011 (UTC)

:Not terribly impressed by the C++ example either - don't expose pointers, use references instead, and the Builder certainly cannot be a singleton. As an example, use more meaningful names - ideally (necessarily) the same as those in other examples to emphasis the relationship between the representations in different languages. [[Special:Contributions/15.203.137.74|15.203.137.74]] ([[User talk:15.203.137.74|talk]]) 12:19, 26 November 2014 (UTC)

== C# implementation ==

In keeping with C# style, shouldn't properties be used instead of java-like setters?

<sourcesyntaxhighlight lang = "csharp">

public string Dough {

get {return _dough;}

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}

...

</syntaxhighlight>

</source>

== Critics ==

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:Using setters is not a replacement, because setters can cause the object to have an unstable and incomplete form. Builder pattern guarantees that the only object that is modified is the intermediatate object used while creating the final product. When the intermediate object is used up it is discarded. Builder pattern also allows flexible object construction. Suppose you have an object that might need many parameters. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/130.243.188.76|130.243.188.76]] ([[User talk:130.243.188.76|talk]]) 22:50, 13 December 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

=== page confusingly mixes two different unrelated builder patterns in its examples and explanations===

The java example is not the "GOF builder pattern". It's actually the "java builder pattern" (which is really a just a [[Fluent_interface]]). TheyThe GOF builder and the "java builder" are significantly different unrelated patterns. The java builder pattern is a wrapper for collecting settings used to eventually construct an object when you've collected enough. And it does it in an easy to read / write "sentence structure" ie: new CarBuilder().wheels(4).paint("blue").type("sedan").interior("leather").makeItSo(); You can use it to with a protected constructor so that all entities that want to build an object have to use the builder to do it. You can also use this java builder pattern in scala to build immutable objects. So that is the java builder pattern. TheresThere's no director class for this type of builder. When the page is talking about the builder pattern being a wrapper around a constructor, its talking about thisthe "java / fluent interface" pattern.

The GOF builder pattern is not like this at all. Whereas the java builder pattern is more about convenient sentence like construction, the GOF builder is more about building a complex/compound object withusing encapsulated builders (builders that no nothing about each other). andAnd oneit directoruses thata can provide them with what each builder needsdirector to get started and coordinate/orchestrate theirthe work allocated to eventuallyeach builder to make the final compound object. So in the car example, you'd have builders that more resemble steps in the car assembly with the director representing the "conveyor belt(s) / build process".

with that in mind, I think this page should bejust splitrefer into 2 sections, one forto the GOF pattern and onehave foran ambiguity link to link the Java buildbuilder pattern to the [[Fluent_interface]] page.

<ref>http://stackoverflow.com/questions/26256604/is-the-java-builder-pattern-bloch-really-related-to-the-gof-builder</ref>

[[User:Normana400|Normana400]] ([[User talk:Normana400|talk]]) 18:47, 17 March 2017 (UTC)

{{reflist-talk}}

== Wrong example ==

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disappears:

<sourcesyntaxhighlight lang="python">

class Pizza:

def __init__(self,dough='Hand Tossed', sauce='Marinara', topping='Cheese'):

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# Use the standard dough

p = Pizza(sauce='Garlic Butter', topping='Pepperoni')

</syntaxhighlight>

</source>

...But then, the "Definition" section of the article says this:

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A less abstract example might be DocumentBuilder with addParagraph, addImage etc methods. Then we could have a PdfDocumentBuilder, WordDocumentBuilder etc implementations. [[Special:Contributions/81.187.215.34|81.187.215.34]] ([[User talk:81.187.215.34|talk]]) 11:23, 10 July 2016 (UTC)

:The current example is no longer about cars. [[User:Dandv|<span style="text-shadow:lightgrey 0.3em 0.3em 0.15em;">Dandv</span>]] 04:33, 6 October 2022 (UTC)

== UML class and sequence diagram ==

I would like to share the following [[Unified Modeling Language|UML]] diagrams I have published on [http://www.w3sdesign.com Design Patterns Open Online Learning]. Your comments are welcomed!

[[File:w3sDesign Builder Design Pattern UML.jpg|frame|none|A sample UML class and sequence diagram for the Builder design pattern.]]

In the above [[Unified Modeling Language|UML]] [[Class diagram|class diagram]],

the <code>Director</code> class doesn't instantiate the <code>ProductA1</code> and <code>ProductB1</code> classes directly.

Instead, the <code>Director</code> refers to the <code>Builder</code> interface to create the objects,

which makes the <code>Director</code> independent of which concrete classes are instantiated (which representation of the complex object is created).

The <code>Builder1</code> class implements the <code>Builder</code> interface by creating and assembling the <code>ProductA1</code> and <code>ProductB1</code> objects

<br>

The [[Unified Modeling Language|UML]] [[Sequence diagram|sequence diagram]] shows the run-time interactions:

The <code>Director</code> object calls <code>buildPartA()</code> on the <code>Builder1</code> object, which creates and assembles the <code>ProductA1</code> object.

Thereafter,

the <code>Director</code> calls <code>BuildPartB()</code> on <code>Builder1</code>, which creates and assembles the <code>ProductB1</code> object. <br>

[[User:Vanderjoe|Vanderjoe]] ([[User talk:Vanderjoe|talk]]) 15:42, 5 August 2017 (UTC)<br>

== The many code examples seem unneeded. ==

If the point of the article is to convey the idea behind the pattern, I think the many, many different language implementations are unnecessary. By display length, the Examples section, with implementations in 9 (!) different languages takes up 80% of the article. This seems quite superfluous, since, unlike, say, an article on a sorting algorithm, nobody is going to copy and paste any of this code into their program.

I'd prefer to either completely remove the Examples section, or only keep, at most, a single language (don't care which).

[[User:Mlouns|Mlouns]] ([[User talk:Mlouns|talk]]) 22:43, 3 June 2019 (UTC)

:This was resolved. Can we delete the section? [[User:Dandv|<span style="text-shadow:lightgrey 0.3em 0.3em 0.15em;">Dandv</span>]] 04:32, 6 October 2022 (UTC)

== Confusing Bicycle example ==

I find the Pizza example given on this Talk page in 2007 ([[#Builders_and_immutable_objects]]) far easier to follow than the [https://en.wikipedia.org/w/index.php?title=Builder_pattern&oldid=1102311912#Examples current Bicycle example]. -- [[User:Dandv|<span style="text-shadow:lightgrey 0.3em 0.3em 0.15em;">Dandv</span>]] 04:30, 6 October 2022 (UTC)