[CMake] Function variable name question

[James Bigler]

On Tue, Jan 27, 2009 at 10:46 AM, Matthew Woehlke <
mw_triad at users.sourceforge.net> wrote:

> James Bigler wrote:
>
>> I have the following code in a script:
>>
>> function(set_var var)
>>  message("var = ${var}")
>>  message("${var} = ${${var}}")
>>  set(${var} "new_val")
>>  message("${var} = ${${var}}\n")
>> endfunction()
>>
>> set(myvar 10)
>> set_var(myvar)
>>
>> # Empty variable
>> set_var(myvar2)
>>
>> set_var(var)
>>
>> # Set variable
>> set(var 11)
>> set_var(var)
>>
>> When I run it I get the following output:
>>
>> var = myvar
>> myvar = 10
>> myvar = new_val
>>
>> var = myvar2
>> myvar2 =
>> myvar2 = new_val
>>
>> var = var
>> var = var
>> new_val =
>>
>> var = var
>> var = var
>> new_val =
>>
>> I get expected output when the name of the variable I pass in isn't the
>> same
>> as the one used in the function parameter list.
>>
>> Is this the desired behavior of the language?  I would argue that it
>> isn't,
>> because you get different behavior based on the name of the variable
>> passed
>> in.
>>
>
> Um... and how would you claim it is supposed to work? You've got a classic
> case of variable shadowing here. If you think about it, CMake is doing
> exactly what you told it to do.
>
> IOW, don't do that ;-).
>

Grrrr....I see that now.

${var} evaluates to var and there's no way to know if that's the function's
var or the global scope's var.

I know you could probably mangle the parameter names to decrease the
probability of collisions, but is there any assured method to avoid
collisions?

James
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