rfc:closures

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rfc:closures [2009/03/17 14:27] – Note $this isn't available any more scottmacrfc:closures [2009/12/15 22:40] – Fix list numbering rquadling
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 Closures and lambda functions can make programming much easier in several ways: Closures and lambda functions can make programming much easier in several ways:
- 
 ==== Lambda Functions ==== ==== Lambda Functions ====
  
 Lambda functions allow the quick definition of throw-away functions that are not used elsewhere. Imagine for example a piece of code that needs to call preg_replace_callback(). Currently, there are three possibilities to achieve this: Lambda functions allow the quick definition of throw-away functions that are not used elsewhere. Imagine for example a piece of code that needs to call preg_replace_callback(). Currently, there are three possibilities to achieve this:
- +  - Define the callback function elsewhere. This distributes code that belongs together throughout the file and decreases readability. 
-   - Define the callback function elsewhere. This distributes code that belongs together throughout the file and decreases readability. +  - Define the callback function in-place (but with a name). In that case one has to use function_exists() to make sure the function is only defined once. Here, the additional if() around the function definition makes the source code difficult to read. Example code:<code php>
- +
-   - Define the callback function in-place (but with a name). In that case one has to use function_exists() to make sure the function is only defined once. Here, the additional if() around the function definition makes the source code difficult to read. Example code: +
- +
-<code php>+
    function replace_spaces ($text) {    function replace_spaces ($text) {
      if (!function_exists ('replace_spaces_helper')) {      if (!function_exists ('replace_spaces_helper')) {
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    }    }
 </code> </code>
- +  - Use the present create_function() in order to create a function at runtime. This approach has several disadvantages: First of all, syntax highlighting does not work because a string is passed to the function. It also compiles the function at run time and not at compile time so opcode caches can't cache the function.
-   - Use the present create_function() in order to create a function at runtime. This approach has several disadvantages: First of all, syntax highlighting does not work because a string is passed to the function. It also compiles the function at run time and not at compile time so opcode caches can't cache the function.+
  
 ==== Closures ==== ==== Closures ====
rfc/closures.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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