Do powershell parameters need to be at the front of the script?

Question

I'm trying to have a script with both executable code and a function, like the following:

function CopyFiles {
 Param( ... )
...
}

// Parameter for the script
param ( ... ) 

// Executable code

However, I run into the following error: "The assignment expression is not valid. The input to an assignment operator must be an object that is able to accept assignments, such as a variable or a property"

When I list my function at the end of the file, it says that the function name is undefined. How do I call a powershell function from executable code within the same script?

Answer 1

The correct order is:

1.Script parameters

# Parameter for the script
param([string]$foo) 

2.Function definitons

function CopyFiles {
    Param([string]$bar)
    ...
}

3.Script code

# Executable code
CopyFiles $foo $bar

Why would you want it any other way?

Answer 2

Parameters go first always. I had a similar issue at one point in time with providing parameter input to a script. Your script should go:

param ( . . . )
# functions
# script body

For some reason, the PowerShell parsing engine doesn't appreciate the param keyword not being on the first line of a script, not counting comment lines. You can also do this:

param (
# params must be at the top of the file
)

You can also check to see if your parameters have been declared, or if they have the input you want, using Get-Variable. One other thing; if you want to cast data to a certain type, such as System.Boolean, I would do it AFTER the param block, and BEFORE functions. If you type-cast something to System.Boolean in the parameter declaration, then you'll have errors if people running your script don't submit the input argument in a Boolean value, which is much harder than using the .NET System.Convert static method to convert the value afterwards, and checking to see what it evaluated to.