On 06/28/2010 08:55 AM, Michael Wild wrote: > > On 28. Jun, 2010, at 7:03 , Andreas Mohr wrote: > >> Hello, >> >> On Sun, Jun 27, 2010 at 05:09:41PM -0400, cmake-requ...@cmake.org wrote: >>> Your remarks focus on old-fashioned macros so it is possible you are not >>> aware of functions? As far as I know, most or all macros can be replaced by >>> functions which do have the nice property of not polluting the global >>> namespace. So newly developed build systems should use functions wherever >>> possible, and certainly for old CMake-based build systems I am associated >>> with I am trying to move to functions as time permits. >> >> That's all fine and dandy (and you've written some nice prose about >> it :), but I've just been reading man cmakecommands of Debian cmake >> 2.8.1-5(!) from top to bottom and bottom to top, and nowhere does it >> mention _any_ underlying difference between macros and functions.
As for me, I wouldn't say so. The documentation of MACRO() states: "Note that the parameters to a macro and values such as ARGN are not variables in the usual CMake sense. They are string replacements much like the c preprocessor would do with a macro. If you want true CMake variables you should look at the function command." So, one could conclude that there's indeed a difference between macros and functions particularly in regard to variables, i.e. one of this thread's concerns. >> Not even I knew about this difference, despite having almost a month-full >> of rather very internal CMake experience (Google searches in the couple >> hundreds, vcproj2cmake adaptation of a _large_ project etc.). >> >> Suggestion for the sake of world peace: I'll submit a patch for that man >> page, ok? :) >> >> Andreas Mohr >> > > You are right, the docs don't mention that FUNCTION introduces a new scope, > [...] They do, but not for FUNCTION() where such facts would be expected; it's rather hidden in the section of SET() w.r.t. PARENT_SCOPE: "If PARENT_SCOPE is present, the variable will be set in the scope above the current scope. Each new directory *or function* creates a new scope. This command will set the value of a variable into the parent directory or calling function (whichever is applicable to the case at hand)." > [...] which should be fixed. [...] Yes, mentioning the scoping capabilities of FUNCTION() right in the latter's documentation, perhaps in connection with a reference to SET()'s PARENT_SCOPE option, would be adequate and helpful, IMO. Besides, ADD_SUBDIRECTORY()'s documentation doesn't note the introduction of a new scope, too. > [...] But it should be clear from the traditional use of the names. Macros > are textual replacements (just as in C), functions have their own local scope > (again, just as in C). Regards, Michael _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://www.cmake.org/mailman/listinfo/cmake
