Wikipedia:Tip of the day/November 26, 2006
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Pick from a list of template parameter choices
Do you have a list of possible choices for a template parameter? Use the #switch parser function to define the choices. Then simply enter the choice's numeric value into the template for the applicable parameter, e.g., 1="Sunday" 2="Monday" 3="Tuesday" ... Default choices also can be listed. For simplicity with lists, use a switch statement instead of a "nested if-then-else" conditional statement to control flow.
Read more:
m:ParserFunctions - #switch: