Home THE HYPERCARD CENTER

HyperTalk Reference
Home » HyperTalk Reference » HyperTalk basics

Note: This is a work in progress and will be formatting errors. Read more about the project on the home page.

Writing function handlers

When you write a handler for a function, you specify statements that compute and return a value to the handler that calls the function. Each function handler has the following form, where the italicized words are placeholders:

function functionName
    statements
end functionName

HyperCard has many built-in functions, but you can also write your own:

on mouseUp
   put square(5) into the Message box
end mouseUp
function square x
   return (x * x)
end square

The function square receives a number through its parameter variable, x. It then returns the value of x * x to the handler that called it (mouseUp) using the return keyword.


Placeholders

functionName
Any text string, without quotation marks, that represents the name of the function handler you want to write:

myAverage
onlyOneWindow
As in the HyperTalk examples:
function myAverage theNumbers
function onlyOneWindow


statements
Any return-separated list of built-in commands, user-defined handlers, or keywords that are part of a message or function handler.

put "Hello world"   -- built-in command
get total(field 1)  -- function call
global HelpInfo     -- keyword


Related Topics

« Using parameter variables | HyperTalk Reference | The building blocks »


Version 0.7b1 (March 24, 2022)

Made with Macintosh

Switch to Modern View

Home
The HyperCard Center
HyperTalk Reference
Home » HyperTalk Reference » HyperTalk basics

Note: This is a work in progress and will be formatting errors. Read more about the project on the home page.

Writing function handlers

When you write a handler for a function, you specify statements that compute and return a value to the handler that calls the function. Each function handler has the following form, where the italicized words are placeholders:

function functionName
    statements
end functionName

HyperCard has many built-in functions, but you can also write your own:

on mouseUp
   put square(5) into the Message box
end mouseUp
function square x
   return (x * x)
end square

The function square receives a number through its parameter variable, x. It then returns the value of x * x to the handler that called it (mouseUp) using the return keyword.


Placeholders

functionName
Any text string, without quotation marks, that represents the name of the function handler you want to write:

myAverage
onlyOneWindow
As in the HyperTalk examples:
function myAverage theNumbers
function onlyOneWindow


statements
Any return-separated list of built-in commands, user-defined handlers, or keywords that are part of a message or function handler.

put "Hello world"   -- built-in command
get total(field 1)  -- function call
global HelpInfo     -- keyword


Related Topics

« Using parameter variables | HyperTalk Reference | The building blocks »

Version 0.7b1 (March 24, 2022)

Made with Macintosh

Switch to Retro View