OpenStruct
An OpenStruct is a data structure that allows the definition of arbitrary methods and properties at runtime., (*1)
Installation
If you're using composer simply add the einstein/open-struct dependency to your composer.json file., (*2)
Otherwise you can manually install it by cloning the repository somewhere in your php include_path., (*3)
git clone git@github.com:einstein/open_struct.git`
require 'open_struct/open_struct.php';
Usage
$person = new OpenStruct;
$person->name = 'John';
$person->age = 35;
echo $person->name; # => 'John'
echo $person->age; # => 35
echo $person->address; # => null
OpenStruct uses an array internally to store properties and can even be initialized with one:, (*4)
$person = new OpenStruct(array('name' => 'John', 'age' => 35));
echo $person->name; # => 'John'
echo $person->age; # => 35
echo $person->address; # => null
print_r($person->properties); # => array('name' => 'John', 'age' => 35)
OpenStruct objects can extend classes allowing new methods to be defined at runtime ($this even resolves correctly):, (*5)
class AssetHelpers {
function asset_path($path) {
return '/assets/'.$path;
}
}
$helpers = new OpenStruct;
$helpers->extend('AssetHelpers');
echo $helpers->asset_path('cat.png'); # => '/assets/cat.png'
echo $helpers->asset_path('dog.png'); # => '/assets/dog.png'
Methods can even be overridden (notice the call to $this->super() which references the example above):, (*6)
class S3AssetHelpers {
function asset_path($path) {
return 'http://'.$this->s3_bucket.'.s3.amazonaws.com'.$this->super($path);
}
}
$helpers->extend('S3AssetHelpers');
$helpers->s3_bucket = 'example';
echo $helpers->asset_path('cat.png'); # => 'http://example.s3.amazonaws.com/assets/cat.png'
echo $helpers->asset_path('dog.png'); # => 'http://example.s3.amazonaws.com/assets/dog.png'
print_r($helpers->ancestors); # => array('S3AssetHelpers', 'AssetHelpers')
Note that super can only be called from within a method:, (*7)
$struct = new OpenStruct;
$struct->super(); # => BadMethodCallException - Undefined method OpenStruct::super()
A wildcard/catch-all method method_missing can be defined as well (equivalent of PHP's __call), (*8)
$person = new OpenStruct(array('name' => 'Bob'));
$person->get_name(); # => BadMethodCallException - Undefined method OpenStruct::get_name()
class Getters {
function method_missing($method, $arguments) {
if (preg_match('/^get_(.+)$/', $method, $matches) && isset($this->{$matches[1]})) {
return $this->{$matches[1]};
} else {
return $this->super($method, $arguments);
}
}
}
$person->extend('Getters');
$person->get_name(); # => 'Bob'
$person->get_age(); # => BadMethodCallException - Undefined method OpenStruct::get_age()
$person->undefined(); # => BadMethodCallException - Undefined method OpenStruct::undefined()
If you extend a class that has a static method called extended, it will be called and
passed the current OpenStruct instance and any additional parameters passed to extend as arguments., (*9)
You can use it like a constructor/initializer:, (*10)
class S3AssetHelpers {
static function extended($struct, $bucket = 'example') {
$struct->s3_bucket = $bucket;
}
function asset_path($path) {
return 'http://'.$this->s3_bucket.'.s3.amazonaws.com/'.$path;
}
}
$helpers = new OpenStruct;
$helpers->extend('S3AssetHelpers', 'test');
echo $helpers->asset_path('cat.png'); # => 'http://test.s3.amazonaws.com/cat.png'
echo $helpers->asset_path('dog.png'); # => 'http://test.s3.amazonaws.com/dog.png'
The extend method also accepts an array of classes to extend as the first argument. These method calls all do the same thing:, (*11)
$struct = new OpenStruct;
$struct->extend(array('AssetHelpers', 'S3AssetHelpers'));
$struct->extend('AssetHelpers');
$struct->extend('S3AssetHelpers');
$struct->extend('AssetHelpers')->extend('S3AssetHelpers');
PHP has many reserved keywords that throw fatal errors
when you try to define them as methods e.g. function include() { }. OpenStruct allows you to define methods
with keyword names by prefixing them with __ e.g. function __include() { }. This allows you to call
$struct->include() without throwing fatal errors., (*12)
OpenStruct also includes an eval method which accepts a $file and optional array of $locals. It will
extract any locals and include
$file within the context of the OpenStruct instance. It also accepts an optional third argument $extract_properties
which will also extract references to all of the OpenStruct instance's properties before including $file.
$extract_properties defaults to false., (*13)
Testing
OpenStruct tests require jaz303/ztest, (*14)
Simply download it to open_struct/test/ztest (or anywhere else in your PHP include_path), then run test/run, (*15)
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