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Product Edition
Version
param
Basics
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Type
Function
Syntax
the param of parameterNumber param(parameterNumber)
Introduced
1.0
Environment
Desktop, Web and Server
Platform Support
MacOS,Mac OS X,Windows,Linux
Security
None required
Summary
Returns the specified parameterpassed to the current handler.
Examples

param(3) -- returns the third parameter
param(0) -- returns the handler name

Additional Comments
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Use the param function within a handler to get the value of a parameter when you don't know in advance how many parameters will be passed to the handler.

Parameters:

The parameterNumber is a non-negative integer.

Value:

The param function returns the parameter value specified by the parameterNumber. If the parameterNumber is zero, the param function returns the handler name.

Comments:

Usually, you assign names to parameters in the first line of a function handler or message handler. For example, the following function assigns three parameters, which are multiplied together:

function product firstFactor,secondFactor,thirdFactor

return firstFactor * secondFactor * thirdFactor

end product

But if you want to multiply all the numbers passed to the function handler together, you don't know ahead of time how many parameters will be passed, so you can't assign a parameter name (such as firstFactor) to each one in the first line of the function handler. In this case, you can use the param function to use each parameter without needing to assign it a name:

function product

put 1 into total

repeat with nextFactor = 1 to the paramCount

multiply total by param(nextFactor)

end repeat

return total

end product

Revolution evaluates the parameters before passing them. So if you call myHandler with the following statement:

myHandler 1+1,"A","Hello" && "world"

the parameters returned by the param function are 2, A, and "Hello World".

User Comments
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shaosean@wehostmacs.com
StarStarStarStarStar
Apr 30, 2009
If you write commands that have a variable length of parameters but the last one is always the same one, example:


command moo p1, p2[, p3][,p4]

You can easily get the last parameter without messing around with lots of "IF" or "SWITCH" statements by using


param(paramCount())