Help:Parser functions in templates/pt-br

Ao aplicar as ParserFunctions nos parâmetros das templates, a a barra vertical ("|") pode ser utilizada para fornecer a string vazia como valor padrão, a fim de indicar a forma de lidar com as coisas, se um parâmetro é ou não passado.


 *  


 * Exemplo A:  


 * Resultado: 


 *  


 * Exemplo B:  


 * Resultado: 


 * Comparação

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.

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):

Note that the wrapped_template</tt> receives a specified but empty normal_parameter</tt> in two cases: when normal_parameter</tt> is specified and empty, and when normal_parameter</tt> is unspecified (because the default empty value is then specified by the wrapper template).

By contrast, the wrapped_template</tt> receives a specified sensitive_parameter</tt> only when it is indeed specified, because the #if</tt> changes the wrapped_template</tt> parameter name to « sensitive_parameterNULL</tt> » when sensitive_parameter</tt> is undefined.

Note also that wrapped_template</tt> receives a specified and empty sensitive_parameter</tt> only when the wrapper template receives a specified and empty sensitive_parameter</tt>. Of course, one must make sure the suffixed wrapped_template</tt> parameter name is meaningless to the wrapped_template</tt> for this to work properly.

Ver também

 * Help:Extension:ParserFunctions
 * Help:Template
 * Extension:Loops#forargs