rfc:catchable-call-to-member-of-non-object

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rfc:catchable-call-to-member-of-non-object [2014/04/28 01:02] – thekidrfc:catchable-call-to-member-of-non-object [2014/04/29 07:26] – Add inner workings thekid
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 ====== PHP RFC: Catchable "call to a member function of a non-object" ====== ====== PHP RFC: Catchable "call to a member function of a non-object" ======
-  * Version: 1.0+  * Version: 1.1
   * Date: 2014-04-26   * Date: 2014-04-26
   * Author: Timm Friebe <thekid@php.net>   * Author: Timm Friebe <thekid@php.net>
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 ==== Example: Without exceptions ==== ==== Example: Without exceptions ====
-This could be a way for people preferring not to use exceptions and instead to exit the script directly, but get a clean stacktrace instead of just the fatal error message:+This could be a way for people preferring not to use exceptions and instead to exit the script directly, but get a stacktrace instead of just the fatal error message:
  
 <PHP> <PHP>
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 ==== Differences from Past RFCs ==== ==== Differences from Past RFCs ====
 This proposal doesn't go as far as the controversial RFC [[engine_exceptions|RFC: Engine exceptions]]. This proposal doesn't go as far as the controversial RFC [[engine_exceptions|RFC: Engine exceptions]].
 +
 +==== Inner workings ==== 
 +
 +Taken this code:
 +
 +<PHP>
 +function a($comparator) {
 +  $result= $comparator->compare(1, 2);
 +  // ...
 +}
 +</PHP>
 +
 +You can unwind this to something like:
 +
 +  function a($comparator) {
 +    1: ZEND_INIT_METHOD_CALL $comparator 'compare'
 +    2: ZEND_SEND_VAL         1
 +    3: ZEND_SEND_VAL         2
 +    4: ZEND_DO_FCALL_BY_NAME
 +    5: ZEND_ASSIGN           $result
 +    // ...
 +  }
 +
 +The handling on checking whether the method is callable happends inside
 +the opline #1 (''ZEND_INIT_METHOD_CALL''). The opcode handler for it 
 +checks its first argument (here: ''$comparator'') whether it is an object
 +or not. In case it's not, the following happens:
 +
 +  - A recoverable error is triggered. Should the script exit here, there's nothing more to be done, this is just as it was before.
 +  - In case the script continues, all the oplines are skipped until we find the ''FCALL_BY_NAME'' opcode. This is comparable to jumping forward just as, e.g., the ''ZEND_JMP'' instruction would.
 +  - The return value is set to ''ZVAL_NULL()''.
 +  - The control is handed back to the executor, which then continutes with the ''ASSIGN'' opcode.
 +
  
 ===== Other Impact ===== ===== Other Impact =====
rfc/catchable-call-to-member-of-non-object.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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