oldFunction: Difference between revisions
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Verisimilar (talk | contribs) m (Clarified that user-defined functions can be redefined as well, and gave a basic explanation of function chaining.) |
Verisimilar (talk | contribs) m (Removed stub, added a bit more clarification.) |
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{{MacroFunction | {{MacroFunction | ||
|name=oldFunction | |name=oldFunction | ||
|version=1.3b51 | |||
|description= | |description= | ||
If a user-defined function redefines a standard MapTool function or another user-defined function -- for instance, a user defines a function called {{code|eval()}}, redefining the standard MapTool {{func|eval}} -- {{func|oldFunction}} can be used in the user-defined function to call the original function. When a user-defined function redefines an existing function, it keeps track of the function that it redefined. Due to this tracking, it is possible to redefine a function multiple times and {{func|oldFunction}} will always reference the previous function in the chain. | If a user-defined function redefines a standard MapTool function or another user-defined function -- for instance, a user defines a function called {{code|eval()}}, redefining the standard MapTool {{func|eval}} -- {{func|oldFunction}} can be used in the user-defined function to call the original function. When a user-defined function redefines an existing function, it keeps track of the function that it redefined. Due to this tracking, it is possible to redefine a function multiple times and {{func|oldFunction}} will always reference the previous function in the chain. | ||
'''Note:''' Do not rely on a specific order in the function chain unless you are sure that the functions will be redefined in that order. Calls to {{func|defineFunction}} within [[onCampaignLoad]] macros on different [[Library Token]]s are not executed in any standard order. | |||
|usage= | |usage= | ||
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{{param|SPECIAL|oldFunction supports the same parameters as the function that it is referencing.}} | {{param|SPECIAL|oldFunction supports the same parameters as the function that it is referencing.}} | ||
| | |example= | ||
Used within a user defined function named {{code|eval()}}, oldFunction() is used to call the standard {{func|eval}}. | Used within a user-defined function named {{code|eval()}}, oldFunction() is used to call the standard MapTool {{func|eval}} function. | ||
<source lang="mtmacro" | <source lang="mtmacro"> | ||
[h, if ( arg(0) == 0 ), code: | [h, if ( arg(0) == 0 ), code: | ||
{ | { | ||
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}] | }] | ||
</source> | </source> | ||
By having access to the original function definition, this example is able to provide both custom and standards return values when called. | |||
|also= | |also= | ||
Revision as of 22:51, 16 April 2009
oldFunction() Function
• Introduced in version 1.3b51
If a user-defined function redefines a standard MapTool function or another user-defined function -- for instance, a user defines a function called
eval(), redefining the standard MapTool eval() -- oldFunction() can be used in the user-defined function to call the original function. When a user-defined function redefines an existing function, it keeps track of the function that it redefined. Due to this tracking, it is possible to redefine a function multiple times and oldFunction() will always reference the previous function in the chain.
Note: Do not rely on a specific order in the function chain unless you are sure that the functions will be redefined in that order. Calls to defineFunction() within onCampaignLoad macros on different Library Tokens are not executed in any standard order.Usage
oldFunction(SPECIAL)Parameter
SPECIAL- oldFunction supports the same parameters as the function that it is referencing.
Example
Used within a user-defined function named
By having access to the original function definition, this example is able to provide both custom and standards return values when called.
eval(), oldFunction() is used to call the standard MapTool eval() function.
[h, if ( arg(0) == 0 ), code:
{
[h: macro.return = 0]
};{
[h: macro.return = oldFunction( arg(0) ) ]
}]