I am used to working in languages such as C#/Java/Python where each class would have its own file, and for a class to see other classes, you would import the package containing those classes. How does this work in php? The documentation shows you how to create classes, but I don't understand how it all fits together in a php context. I know of the include statement, which just sticks the files together basically.
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3possible duplicate of Import package or autoloading for PHP?Gordon– Gordon2011-01-21 11:05:36 +00:00Commented Jan 21, 2011 at 11:05
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2(tipp) search for autoloading and code conventions in PHPGordon– Gordon2011-01-21 11:06:18 +00:00Commented Jan 21, 2011 at 11:06
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Personally, I find it very sensible to have each class in its own file... but use an autoloader rather than java's importMark Baker– Mark Baker2011-01-21 11:07:26 +00:00Commented Jan 21, 2011 at 11:07
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@middaparka: I was the subject of a completely off-topic (although short-lived) discussion just the other day.BoltClock– BoltClock2011-01-21 11:18:38 +00:00Commented Jan 21, 2011 at 11:18
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@middaparka: The comment that started it was removed by flagging, but contextual remnants can be found in meagar's reply here.BoltClock– BoltClock2011-01-21 11:49:50 +00:00Commented Jan 21, 2011 at 11:49
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5 Answers
You can use __autoload
function __autoload($class_name) {
include 'classes/'.$class_name . '.php';
}
So place every single class in its own file in the classes folder. When you want to use that class it will include it. More info: http://php.net/manual/en/language.oop5.autoload.php
Update: When I answered this it was fully valid. Now it still works, but keep in mind PHP.net since then says this:
spl_autoload_register() provides a more flexible alternative for autoloading classes. For this reason, using __autoload() is discouraged and may be deprecated or removed in the future.
1 Comment
Mchl
Also take a look at: php.net/manual/en/function.spl-autoload-register.php
The easiest way:
- define your classes in "classes" directory
- init application like shown below
- name class filenames as their lowercase class name with .php suffix (MyClass => classes/myclass.php)
Init code:
set_include_path ( "./classes" );
spl_autoload_register ();
//class is automatically loaded from ./classes/myclass.php
$object_instance = new MyClass ();
Comments
As of PHP 5.3.0 , it is recommended that you use the spl_autoload_register() function because __autoload() is said to be deprecated some time in the future.
An easy way to use this function:
1) Place each class file into the 'classes' folder
2) Run an anonymous function inside spl_autoload_register() which specifies your class folder:
spl_autoload_register(function ($class) {
include 'classes/' . $class . '.php';
});
Now when you try to use a class that is not defined in your code yet, it will check that class folder one last time before giving you an error.
1 Comment
Ákos Nikházy
This is cool but this is best used when you want your own autoloader with its own name as described in Example #1 here: php.net/manual/en/function.spl-autoload-register.php In this case __autoload is enough.
Imagine you have been making your object in PHP in a file called myObject.php
<?php
class myObject
{
public function __construct()
{
echo "Hello, World";
}
}
?>
And in another file, you would like to use the object (let's call this myfile.php). You would have to include your object - like this:
<?php
include("myObject.php");
$intance = new myObject();
?>
Quite simple.
In PHP you can do it in various ways, compiler does not limit you.
You can have 1 class in 1 file, 5 classes in 1 file, 1 class across several files using includes...
But usually it's still 1 class in 1 files, and if you have many tiny ones - you can have them in 1 folder too.
When doing 1 class in 1 file with the same name you can set up class autoload so that you don't need to write your includes.
1 Comment
yokmp
You can NOT have a class split over multiple files. See here for example: stackoverflow.com/questions/1957732/…
