Difference between revisions of "PHP/interface"

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(Created page with "==About== In PHP, an '''interface''' is a set of public method-functions which can be required in either of two circumstances: * in the declaration of a class ** This work...")
 
 
(One intermediate revision by the same user not shown)
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*** narrows down (more closely specifies) the function's expectations of a passed or returned object
 
*** narrows down (more closely specifies) the function's expectations of a passed or returned object
 
*** does not tie the object to a specific class hierarchy
 
*** does not tie the object to a specific class hierarchy
==Functions==
+
==Predefined==
* [https://www.php.net/manual/en/function.interface-exists.php interface_exists()] returns TRUE if the interface has been declared in code that has executed.
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* {{l/sub|instanceof}} works with both classes and interfaces
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** [https://www.php.net/manual/en/language.operators.type.php official]
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* {{l/sub|interface_exists()}} returns TRUE if the interface has been declared in code that has executed.
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** [https://www.php.net/manual/en/function.interface-exists.php official]
 
==Links==
 
==Links==
 
* official: [https://www.php.net/manual/en/language.oop5.interfaces.php interfaces]
 
* official: [https://www.php.net/manual/en/language.oop5.interfaces.php interfaces]
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* '''2018-01-13''' [https://daylerees.com/php-interfaces-explained/ PHP Interfaces Explained]
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==Notes==
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I thought I had derived this rule, but then when I went to test it ''without'' the backslash again, it was working fine:
 +
<blockquote>
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If an interface is declared within a namespace but used outside of that namespace in am "implements" clause, the full namespace path must be prefixed with a backslash or it won't match:
 +
<source lang=php>class fcrUserAcct_admin extends fcrUserAcct implements fiLinkableRecord, \ferreteria\data\ifEditableRecord, fiEventAware {</source>
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...where <code>ifEditableRecord</code> is being declared inside the <code>ferreteria\data</code> namespace.
 +
 +
For all other uses, the backslash is optional or forbidden.
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</blockquote>
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Perhaps there was some kind of code-caching error? If it happens again, try the backslash.

Latest revision as of 01:27, 13 January 2020

About

In PHP, an interface is a set of public method-functions which can be required in either of two circumstances:

  • in the declaration of a class
    • This works almost identically to declaring the interface's methods as abstract functions in a trait or parent class.
  • the type of a function argument or return value
    • Advantages over declaring the object as a class:
      • narrows down (more closely specifies) the function's expectations of a passed or returned object
      • does not tie the object to a specific class hierarchy

Predefined

Links

Notes

I thought I had derived this rule, but then when I went to test it without the backslash again, it was working fine:

If an interface is declared within a namespace but used outside of that namespace in am "implements" clause, the full namespace path must be prefixed with a backslash or it won't match:

class fcrUserAcct_admin extends fcrUserAcct implements fiLinkableRecord, \ferreteria\data\ifEditableRecord, fiEventAware {

...where ifEditableRecord is being declared inside the ferreteria\data namespace.

For all other uses, the backslash is optional or forbidden.

Perhaps there was some kind of code-caching error? If it happens again, try the backslash.