[CMake] Passing Function Arguments

[Johny]

On 07/08/2010 10:44 AM, Michael Wild wrote:
> On 8. Jul, 2010, at 10:35 , Johny wrote:
>
>    
>> I am trying to write a cmake function which imitates the functionality of wc -l for unix. However i can't seem to be able to figure out how to store the result into the variable which is passed  to the function.
>>
>> function (wcl fileName lines)
>>   file(READ ${fileName} fileData)
>>   if(fileData)
>>     string(REGEX MATCHALL "\n" lines ${fileData})
>>     list(LENGTH lines lines)
>>   endif(fileData)
>> endfunction()
>>
>> i call the function as
>>
>> wcl (${fileName} fileLen)
>>
>> and printing it gives no output
>>
>> message("${fileLen}")
>>
>> What am i doing wrong ?
>>
>> Regards
>> Johny
>>      
> A function creates a new scope, so you need to explicitly set the variable in the callers scope. Do something like this (it is usual for the output variable name to be the first argument:
>
> function (wcl nLinesVar fileName)
>   file(READ ${fileName} fileData)
>   if(fileData)
>     string(REGEX MATCHALL "\n" nLines ${fileData})
>     list(LENGTH nLines nLines)
>     set(${nLinesVar} ${nLines} PARENT_SCOPE)
>   else()
>     set(${nLinesVar} -1 PARENT_SCOPE)
>   endif()
> endfunction()
>
> wcl (fileLen ${fileName})
>
> However, I'm not sure whether counting \n is a good idea (after all, at some point you might encounter a file with Windows or Mac line endings, or a file with a missing terminating \n.
>
> Michael
It works like a charm . Thanks!

I've also modified it a bit for Mac and Windows compatibility but not 
for files that don't end in newlines since all the files i'm using 
always do terminate  with newlines. Here's the modified function

function (wcl _nLinesVar fileName)
  file(READ ${fileName} fileData)
  if(fileData)
    if(WIN32)
      string(REGEX MATCHALL "\r\n" nLines ${fileData})
    else()
      string(REGEX MATCHALL "[\r\n]" nLines ${fileData})
    endif(WIN32)
    list(LENGTH nLines nLines)
    set(${_nLinesVar} ${nLines} PARENT_SCOPE)
  else()
    set(${_nLinesVar} -1 PARENT_SCOPE)
  endif()

Cheers!
Johny