[CMake] Memory cleanup of variables

[Naram Qashat]

Bill Hoffman wrote:
> Naram Qashat wrote:
>> I have a CMake project that I have been testing with various verisons 
>> of CMake 2.4.x and 2.6.x to make sure it works as far back as 2.4.0, 
>> due to not knowing what version of CMake our users will be using since 
>> a lot of them use shells. In some instances, I have to read lines from 
>> a file using a specific regular expression.  With CMake 2.6.x, this 
>> works fine using the file(STRINGS) command.  With CMake 2.4.x, though 
>> (I haven't checked what versions specifically), after reading in a lot 
>> of files, I notice that a "memory exhausted" error comes up. I'm 
>> wondering when CMake cleans up the memory it uses, and if there is a 
>> way around this problem.  I would prefer not to force our uses to use 
>> CMake 2.6.x if their shell provider won't provide them something newer.
>>
> There may have been leaks in 2.4.X, not really much we can do about that 
> now....   What does the your cmake code look like that causes the leak?
> 
> 
> -Bill

I believe it is within this macro of mine:

macro(read_from_file FILE REGEX STRINGS)
   if(CMAKE26_OR_BETTER)
     # For CMake 2.6.x or better, we can just use the STRINGS sub-command to get 
the lines that match the given regular expression (if one is given, otherwise 
get all lines)
     if(REGEX STREQUAL "")
       file(STRINGS ${FILE} RESULT)
     else(REGEX STREQUAL "")
       file(STRINGS ${FILE} RESULT REGEX ${REGEX})
     endif(REGEX STREQUAL "")
   else(CMAKE26_OR_BETTER)
     # For CMake 2.4.x, we need to do this manually, firstly we read the file in
     file(READ ${FILE} ALL_STRINGS)
     # Next we replace all newlines with semicolons
     string(REGEX REPLACE "\n" ";" ALL_STRINGS ${ALL_STRINGS})
     if(REGEX STREQUAL "")
       # For no regular expression, just set the result to all the lines
       set(RESULT ${ALL_STRINGS})
     else(REGEX STREQUAL "")
       # Clear the result list
       set(RESULT)
       # Iterate through all the lines of the file
       foreach(STRING ${ALL_STRINGS})
         # Check for a match against the given regular expression
         string(REGEX MATCH ${REGEX} STRING_MATCH ${STRING})
         # If we had a match, append the match to the list
         if(STRING_MATCH)
           append_to_list(RESULT ${STRING})
         endif(STRING_MATCH)
       endforeach(STRING)
     endif(REGEX STREQUAL "")
   endif(CMAKE26_OR_BETTER)
   # Set the given STRINGS variable to the result
   set(${STRINGS} ${RESULT})
endmacro(read_from_file)

I had done this so I could call the macro and have it work with either 2.6.x or 
2.4.x.

Thanks,
Naram Qashat