[CMake] Bug? project(X T) returns weird error

[Eric Noulard]

2010/7/21 Brian Davis <bitminer at gmail.com>:
> I agree with Olaf.  CMake needs better error reporting for parameter
> checking on macros and functions

Good idea but this seems difficult to do.
In Olaf case it may be doable to spit out a better error message explicitely
saying that "T" was considered as the "<language>" argument of PROJECT,
because PROJECT is a builtin

however...

> I ran into similar with use of:
>
> http://www.cmake.org/Wiki/CMakeMacroParseArguments
>
> where I elided the empty quotes "" and it was as though the macro/function
> it was contained in did not exist as though it could not find the ending
> paren ")".  I realize I should always use functions as specified, but as
> humans inevitably make mistakes it's best to have decent error reporting so
> we can correct our ways.
[...]

In this case the MACRO CMake command has only "positional" arguments handling.
So if you miss-use the ParseArguments macros the better you can do is enhance
the ParseArguments macro in order to do a better job while checking
its arguments.

May be the only way to have a better error reporting would be to have a new

kwmacro(<name> KEYWORD <kw1> arg1 KEYWORD kw2 arg2 .... KEYWORD  kwN argN)

kwmacro(<name>)

that would support keyword call instead of positional call.
i.e.

kwmacro(PARSE_ARGUMENTS
                  KEYWORD PREFIX prefixarg
                  KEYWORD ARGNAMES argnames
                  KEYWORD OPTIONSNAME optnames)

kwmacro(PARSE_ARGUMENTS)

then you MUST call
PARSE_ARGUMENTS(hello world
                                          PREFIX ARG
                                          ARGNAMES "LIST1;LIST2;LIST3"
                                          OPTIONSNAME "OPTION1;OPTION2;OPTION3")

i.e. non keyword argument MUST be given before ANY keywords arg
(pretty much like in Python).

kwmacro as a builtin would set for you

KW_<keyword>_GIVEN to TRUE is the <keyword> have been given.
KW_<keyword>_ARGS to the list of arguments given to <keyword>.
KW_DEFAULTS_ARGS will be the list of positional arguments.

basically it is the feature provided by PARSE_ARGUMENTS but as a
more robust builtin.

-- 
Erk
Membre de l'April - « promouvoir et défendre le logiciel libre » -
http://www.april.org