THE HYPERCARD CENTER

HyperTalk Reference

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Using parameter variables

A handler can receive values (called parameters) and use them as it runs. You represent each value with a parameter variable. A parameter variable always follows the handler name in a comma-separated list.

For example, when running the following mouseUp handler, HyperCard calls sayMessage with two values, "red" and "apple". It then binds these values to the parameter variables color and fruit in the sayMessage handler.

on mouseUp
   sayMessage "red", "apple"
end mouseUp
on sayMessage color, fruit
   put "I want a" && color && fruit
end sayMessage

You can use the variables color and fruit anywhere inside the handler. When HyperCard sees them, it uses the values currently bound to them. (The variables remain bound only while the handler runs.)

Demo Script

on mouseUp
   sayMessage "red", "apple"
 end mouseUp
 

 on sayMessage color, fruit
   put "I want a" && color && fruit & "." into the Message box
 end sayMessage

Related Topics

• function
• on
• Writing function handlers
• Writing message handlers