Hello
I would like to discuss three points
1. naming conventions
2. what if pkg-config sends an error
3. protect already defined variables
------------------------------------
1. naming conventions:
The interface will get a prefix like
pkg_check_modules(LIBNAME ...)
I would prefer to stick close to the command names, so
since INCLUDE_DIRECTORIES -> LIBNAME_INCLUDE_DIRECTORIES
since LINK_DIRECTORIES -> LIBNAME_LINK_DIRECTORIES
since LINK_LIBRARIES / TARGET_LINK_LIBRARIES -> LIBNAME_LINK_LIBRARIES
since ADD_DEFINITIONS -> LIBNAME_DEFINITIONS
rather than
LIBNAME_INCLUDE_DIRS and
LIBNAME_LINK_LIBS ...
----------------------------------
2. what if the lib isn't found
This regards the pkg_check_modules interface. If the lib(s)
wasn't/weren't found or version(s) to low the developer should be able
to react.
IMHO there are two possible solution
first:
pkg_config(MYPREFIX found "lib1 >= ??? lib2 >= ??? ...")
if(NOT found)
# FATAL_ERROR of looking for alternatives ...
endif(NOT found)
second:
pkg_config(MYPREFIX "lib1 >= ??? lib2 >= ??? ...")
if(NOT MYPREFIX_FOUND)
# FATAL_ERROR of looking for alternatives ...
endif(NOT MYPREFIX_FOUND)
What do you're like more?
----------------------------------
3. protect already defined variables
How can we ensure that variables of the module-user won't be overwritten
Just a random example...
set(varname ...)
pkg_module_macro(...)
#...
# using varname
If inside the macro a
SET(varname ...)
happens, the module user will be in trouble.
Is it possible to set variables being private?
If not, we can use a prefix like
PKGCONFIG_PRIVATE_*
for all internal variables. For more complex tasks this may be a little
to verbose. So I played around doing something like this:
MACRO(...)
SET(PKGCONFIG_PRIVATE_list_of_used_vars
version_number_1_digits
version_number_2_digits
version_number_1_digits_count
version_number_2_digits_count
to
digit_is
digit_min
digits_count_min )
PKGCONFIG_PRIVATE_VARS_SAVE(
PKGCONFIG_PRIVATE_list_of_already_used_vars
PKGCONFIG_PRIVATE_list_of_values_of_already_used_vars
${PKGCONFIG_PRIVATE_list_of_used_vars}
)
#
... do the work ....
#
PKGCONFIG_PRIVATE_VARS_RESTORE(
PKGCONFIG_PRIVATE_list_of_already_used_vars
PKGCONFIG_PRIVATE_list_of_values_of_already_used_vars
)
ENDMACRO(...)
where the extra macros are
MACRO(PKGCONFIG_PRIVATE_VARS_SAVE list_of_vars list_of_var_values)
FOREACH(item ${ARGN})
IF(DEFINED ${item})
LIST(APPEND ${list_of_vars} ${item})
LIST(APPEND ${list_of_var_values} ${${item}} )
ENDIF(DEFINED ${item})
ENDFOREACH(item)
ENDMACRO(PKGCONFIG_PRIVATE_VARS_SAVE)
MACRO(PKGCONFIG_PRIVATE_VARS_RESTORE list_of_vars list_of_var_values)
LIST(LENGTH ${list_of_vars} PKGCONFIG_PRIVATE_VAR_1 )
LIST(LENGTH ${list_of_var_values} PKGCONFIG_PRIVATE_VAR_2 )
IF(NOT ${PKGCONFIG_PRIVATE_VAR_1} EQUAL ${PKGCONFIG_PRIVATE_VAR_2} )
MESSAGE(FATAL_ERROR "PKGCONFIG_PRIVATE_VARS_RESTORE: lists got
different length" )
ENDIF(NOT ${PKGCONFIG_PRIVATE_VAR_1} EQUAL
${PKGCONFIG_PRIVATE_VAR_2} )
MATH(EXPR PKGCONFIG_PRIVATE_VAR_1 "${PKGCONFIG_PRIVATE_VAR_1} - 1")
FOREACH(index RANGE ${PKGCONFIG_PRIVATE_VAR_1} )
LIST(GET ${list_of_vars} ${index} PKGCONFIG_PRIVATE_VAR_1 )
LIST(GET ${list_of_var_values} ${index}
PKGCONFIG_PRIVATE_VAR_2 )
set(${PKGCONFIG_PRIVATE_VAR_1} ${PKGCONFIG_PRIVATE_VAR_2})
ENDFOREACH(index)
ENDMACRO(PKGCONFIG_PRIVATE_VARS_RESTORE)
----------------------------------
please spend your 2cents
Regards, Maik
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