Magic Variables: Difference between revisions
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*The most frequently used magic variable probably is <tt>_[[this]]</tt>, which is used to make arguments of a script call ([[call]], [[exec]], [[execVM]], [[spawn]]) visible and accessible to the script. | *The most frequently used magic variable probably is <tt>_[[this]]</tt>, which is used to make arguments of a script call ([[call]], [[exec]], [[execVM]], [[spawn]]) visible and accessible to the script. | ||
*Other uses of magic variables can be seen in [[forEach]], where the current element can be accessed via <tt>_x</tt>. | *Other uses of magic variables can be seen in [[forEach]], where the current element can be accessed via <tt>_x</tt> and the current index with <tt>_forEachIndex</tt>. | ||
*[[Triggers]] also define <tt> | *In the condition of the extended syntax of [[count]] variable <tt>_x</tt> refers to the current tested element. | ||
* [[Exception handling]] using a [[try]]..[[catch]] statement usually declare a magic variable named <tt>_exception</tt>, which contains details about the exception [[throw]]n in the try-block. | *[[Triggers]] also define <tt>[[thisList]]</tt> and <tt>[[thisTrigger]]</tt>, which is however only accessible within the activation or deactivation script. | ||
*[[Exception handling]] using a [[try]]..[[catch]] statement usually declare a magic variable named <tt>_exception</tt>, which contains details about the exception [[throw]]n in the try-block. | |||
Revision as of 17:49, 22 March 2014
Introduction
Magic variables are engine maintained variables that serve a specific purpose within a given scope and are often used by the engine to push data to a given script or code fragment. They are usually no longer present after leaving the scope (e.g. after code execution, or after a forEach statement).
Uses
- The most frequently used magic variable probably is _this, which is used to make arguments of a script call (call, exec, execVM, spawn) visible and accessible to the script.
- Other uses of magic variables can be seen in forEach, where the current element can be accessed via _x and the current index with _forEachIndex.
- In the condition of the extended syntax of count variable _x refers to the current tested element.
- Triggers also define thisList and thisTrigger, which is however only accessible within the activation or deactivation script.
- Exception handling using a try..catch statement usually declare a magic variable named _exception, which contains details about the exception thrown in the try-block.