rfc:heredoc-scanner-loosening

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rfc:heredoc-scanner-loosening [2014/08/29 12:32] – datibbawrfc:heredoc-scanner-loosening [2017/09/22 13:28] – external edit 127.0.0.1
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   * Date: 2014-08-29   * Date: 2014-08-29
   * Author: Tjerk Meesters, datibbaw@php.net   * Author: Tjerk Meesters, datibbaw@php.net
-  * Status: Draft+  * Status: Under Discussion
   * First Published at: http://wiki.php.net/rfc/heredoc-scanner-loosening   * First Published at: http://wiki.php.net/rfc/heredoc-scanner-loosening
  
  
 ===== Introduction ===== ===== Introduction =====
-Currently the rules for ending a heredoc or nowdoc are quite restrictive, requiring a newline after the closing identifier; this makes it more awkward to combine multiple quotations, such as in array declarations or in combination with other operators.+Currently the rules for ending a heredoc or nowdoc are quite restrictive, requiring a newline after the closing identifier; this makes it more awkward to combine multiple quotations, such as in array declarations or with other operators. The [[http://php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc|manual entry]] for heredocs has a big pink box to explain those intricate details.
  
-This proposal aims to loosen or altogether remove that restriction. +For instance, this is how you would declare an array comprising a heredoc and regular string:
- +
-===== Proposal ===== +
-A fix for the following scenario:+
  
 <code php> <code php>
-eval("return <<<EOS\nfoo\nEOS;");+$strings = [<<<EOS 
 +hello 
 +EOS 
 +, ' world'];
 </code> </code>
  
-//The above just illustrates the issue and doesn't advocate using eval().//+The comma that you would normally put on the same line as the previous element must now be put on the next line.
  
-Allow more liberal use in array constructs:+Currently, this restriction also causes a parse error with code such as this: 
 + 
 +<code php> 
 +return <<<EOS 
 +Foo! 
 +EOS; // <-- file ends here 
 +</code> 
 + 
 +===== Proposal ===== 
 +This proposal aims to lift the current newline restriction and make it less awkward to use heredocs and nowdocs within constructs, such as array declarations:
  
 <code php> <code php>
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 </code> </code>
  
-Two ways in which this can be achieved are:+The proposal suggests two distinct ways in which this can be achieved:
  
 ==== Loosened restrictions ==== ==== Loosened restrictions ====
-Ends a quotation as soon as a newline is encountered as well as a few extra characters, i.e. a space, tab, period (concat), comma, ending square bracket (arrays) or null byte (end of file).+Ends a quotation when the closing identifier is followed by something that can't be part of an identifier.
  
 ==== Removed restrictions ==== ==== Removed restrictions ====
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 It emits "ENDOFHEREDOC    ;\nENDOFHEREDOC;" and then stop scanning, leading to a parse error on the next line. It emits "ENDOFHEREDOC    ;\nENDOFHEREDOC;" and then stop scanning, leading to a parse error on the next line.
 +
 +This is a rather extreme example of trying to break the scanner; while not entirely impossible, it's most likely not based on anything one would encounter in the wild.
  
 ==== Removed restrictions ==== ==== Removed restrictions ====
-Removing the restrictions altogether will cause issues like this:+Removing the restrictions altogether will cause issues in code such as this:
  
 <code php> <code php>
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 It emits "Foo bar" and then stops scanning, leading to a parse error at "BLA". It emits "Foo bar" and then stops scanning, leading to a parse error at "BLA".
 +
 +Although this may seem undesirable behaviour, it should be noted that the developer is in complete control of choosing the name for their enclosures; it's important to choose an enclosure that doesn't occur naturally inside the quotation.
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
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 Voting choices will be: Voting choices will be:
   - No, leave the scanner as it is.   - No, leave the scanner as it is.
-  - Yes, loosen the newline restriction with a selected set of characters.+  - Yes, loosen the newline restriction with characters that can't be part of an identifier.
   - Yes, remove the newline restriction altogether.   - Yes, remove the newline restriction altogether.
  
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 ===== Patches and Tests ===== ===== Patches and Tests =====
 The RFC author will provide the patches. The RFC author will provide the patches.
- 
rfc/heredoc-scanner-loosening.txt · Last modified: 2018/06/10 10:26 by cmb

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