Help:Parser functions in templates/fr

Lors de l'emploi d'une fonction de ParserFunctions comme paramètre au sein d'un modèle, un symbole tube («|») doit être utilisé pour fournir une valeur par défaut ; cette dernière étant reprise lorsque le paramètre en question n'est pas défini (vide). Used in an #if parser function, the unexpanded text from the undefined parameter will evaluate as true, which may be an unexpected result.




 * Sample A:


 * Result:




 * Sample B:


 * Result:

The second usage (, sample B) with present empty default is often the desired way to handle situations where a parameter exists, but is comprised only of empty space.

Testing and passing undefined parameters
One way to test whether a parameter was specified in a template call is thus:



In rare cases, a template behaves differently when a parameter is unspecified compared to when it is specified but empty. When this template is used by a wrapper template (which uses the same set of named parameters), one way to ensure undefined parameters remain undefined is as follows (the technique also works with numbered parameters):





receives a defined normal_parameter in all cases. When normal_parameter is defined but empty and when it is undefined,  receives an empty normal_parameter.

By contrast, the  receives a defined sensitive_parameter only when it is indeed defined; when sensitive_parameter is undefined, the   changes the parameter name to sensitive_parameterNULL. The suffixed parameter name must be meaningless to the  for this to work properly.

Voir aussi

 * Extension:Loops#forargs
 * Extension:Loops#forargs
 * Extension:Loops#forargs