Magic Variables: Difference between revisions
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=== Introduction === | === Introduction === | ||
'''Magic variables''' are [[Variables|variables]] that serve a specific purpose within a given scope and are often used by the engine to push data to a given [[Script (File)|script]] or [[Code|code]]. They are usually no longer present after leaving the scope (e.g. after | '''Magic variables''' are engine maintained [[Variables|variables]] that serve a specific purpose within a given scope and are often used by the engine to push data to a given [[Script (File)|script]] or [[Code|code]] fragment. They are usually no longer present after leaving the scope (e.g. after code execution, or after a [[forEach]] statement). | ||
The most frequently used magic variable probably is <tt>_[[this]]</tt>, which is used to make | === Uses === | ||
Other uses of magic variables can be seen in [[forEach]], where the current element can be accessed via <tt>_x</tt>. [[Triggers]] also define <tt>thislist</tt>, which is however only accessible within the activation or deactivation script in the editor. | |||
*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>. | |||
*[[Triggers]] also define <tt>thislist</tt>, which is however only accessible within the activation or deactivation script in the editor. | |||
* [[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 18:19, 5 May 2007
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.
- Triggers also define thislist, which is however only accessible within the activation or deactivation script in the editor.
- 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.