rfc:class-like_primitive_types

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rfc:class-like_primitive_types [2016/12/19 22:00] – ajfrfc:class-like_primitive_types [2016/12/19 22:14] – ajf
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   * <php>$x instanceof array</php>   * <php>$x instanceof array</php>
   * <php>$x instanceof object</php>   * <php>$x instanceof object</php>
-  * <php>$x instanceof resource</php> (**FIXME:** should I omit this?)+  * <php>$x instanceof resource</php>
  
 ==== Features not extended to primitives ==== ==== Features not extended to primitives ====
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 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
- 
-In order to support the <php>instanceof resource</php> syntax, <php>resource</php> must be added to the list of reserved names that cannot be used by classes, interfaces or traits. Otherwise, there would be an ambiguity as to whether this referred to a hypothetical class with the same name, or to the type. This backwards-compatibility break could be avoided by removing support for the resource type (see the Open Issues section). 
  
 **FIXME**  **FIXME** 
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 In JavaScript, ''null'' does not have any properties or methods, but ''true'' and ''false'' do. In contrast, Python's ''None'' (its equivalent to null) //does// have properties and methods, albeit only magic methods. In JavaScript, ''null'' does not have any properties or methods, but ''true'' and ''false'' do. In contrast, Python's ''None'' (its equivalent to null) //does// have properties and methods, albeit only magic methods.
  
-This RFC currently chooses to omit null from support by most of these features.+This RFC currently chooses to omit null from the extension of most features of objects to the other types, but excepts <php>instanceof null</php> because it lacks the same potential to create errors.
  
 ==== Should resource be supported? ==== ==== Should resource be supported? ====
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 Resource is a legacy type that could be wholly replaced by objects in future. Extending these features to this type would be further entrenching it and contrary to the goal of its eventual removal. Resource is a legacy type that could be wholly replaced by objects in future. Extending these features to this type would be further entrenching it and contrary to the goal of its eventual removal.
  
-Beyond that, supporting <php>instanceof resource</php> would require adding ''resource'' to the list of reserved class names (the other types are already on it), and therefore entail a backwards-compatibility break. Omitting support for resources would avoid this backwards-compatibility break.+In particular, <php>instanceof resource</php> could create future backwards-compatibility problems if code uses it to check for values being resources and they later become objects.
  
 ===== Unaffected PHP Functionality ===== ===== Unaffected PHP Functionality =====
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 It also means we can easily introduce new superclasses of our other primitive types. For example, a new <php>\Number</php> type superclassing <php>int</php> and <php>float</php>, or a new <php>\Scalar</php> type superclassing everything except objects and arrays. It also means we can easily introduce new superclasses of our other primitive types. For example, a new <php>\Number</php> type superclassing <php>int</php> and <php>float</php>, or a new <php>\Scalar</php> type superclassing everything except objects and arrays.
 +
 +<php>instanceof</php> could potentially support pseudo-types like <php>callable</php>.
  
 ===== Proposed Voting Choices ===== ===== Proposed Voting Choices =====
rfc/class-like_primitive_types.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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