Proxy pattern: Difference between revisions

Revision as of 16:27, 21 March 2020

Revision as of 18:22, 11 May 2020

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=== PHP ===

<sourcesyntaxhighlight lang="php">

<?php

Line 134:

$image2->displayImage(); // Loading unnecessary

$image1->displayImage(); // Loading unnecessary

</syntaxhighlight>

</source>

The program's output is:

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=== C# ===

<sourcesyntaxhighlight lang="CSharp">

interface ICar

{

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car.DriveCar();

}

</syntaxhighlight>

</source>

Output

Sorry, the driver is too young to drive.

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=== C++ ===

<sourcesyntaxhighlight lang=Cpp>

#include <iostream>

#include <memory>

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car->DriveCar();

}

</syntaxhighlight>

</source>

=== Crystal ===

<sourcesyntaxhighlight lang = Ruby>

abstract class AbstractCar

abstract def drive

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car = ProxyCar.new(driver)

car.drive

</syntaxhighlight>

</source>

Output

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=== Delphi / Object Pascal ===

<sourcesyntaxhighlight lang=Delphi>

// Proxy Design pattern

unit DesignPattern.Proxy;

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end.

</syntaxhighlight>

</source>

Usage

<sourcesyntaxhighlight lang=Delphi>

program Project1;

{$APPTYPE Console}

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TProxyCar.New(TDriver.New(25)).DriveCar;

end.

</syntaxhighlight>

</source>

Output

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The proxy class <tt>ProxyImage</tt> is running on another system than the real image class itself and can represent the real image <tt>RealImage</tt> over there. The image information is accessed from the disk. Using the proxy pattern, the code of the <tt>ProxyImage</tt> avoids multiple loading of the image, accessing it from the other system in a memory-saving manner. The lazy loading demonstrated in this example is not part of the proxy pattern, but is merely an advantage made possible by the use of the proxy.

<sourcesyntaxhighlight lang=Java>

interface Image {

public void displayImage();

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}

}

</syntaxhighlight>

</source>

The program's output is:

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===Python===

<sourcesyntaxhighlight lang="python">

"""

Proxy pattern example.

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car = ProxyCar(driver)

car.drive()

</syntaxhighlight>

</source>

===Rust===

<sourcesyntaxhighlight lang="rust">

trait ICar {

fn drive(&self);

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}

}

</syntaxhighlight>

</source>

==See also==

* [[Composite pattern]]