Re: 'How makefiles are remade'

[Noel Yap]

Jim wrote:

> Hmm not sure how eval equates to include...
>
> Since the actual end in mind is a Makefile.cache, which is the literal 
> expanded targets, rules nessecary to genearte the product defined by the 
> makefile... This must be dependant on all makefiles which  may have 
> changed... the final result is a huge tree of includable .cache files 
> which have the rules needed for all dependants (libraries in other 
> branches, etc )

I'm not sure, but the following may help:


# sets __FILE__ macro to file to be included, then includes the file.
# allows included file to know where it is in relation to includer.
# caching of included makefile is allowed if $(2)!contents is defined as the 
contents of the makefile.
# $(1) is the include method, either "include" or "-include"
# $(2) is the file to be included
# $(3) is the includer
define _include-makefile
  __FILE__ := $(2)

  ifndef $(2)!contents
    # using an order rule suppresses the error when $(1) is "include"
    ifeq ($(wildcard $(dir $(2))),)
      $(shell mkdir -p $(dir $(2)))
    endif

    $(1) $(2)
  else
    $$(eval $$($(2)!contents))
  endif

  __FILE__ := $(3)
endef
# optionally include makefile passing in its name as __FILE__
# allows included file to know where it is in relation to includer.
# caching of included makefile is allowed if $(2)!contents is defined as the 
contents of the makefile.
# $(1) is the file to be included
-include-makefile = $(foreach \
  m, \
  $(1), \
  $(eval $(call _include-makefile,-include,$(m),$(__FILE__))))

# include makefile passing in its name as __FILE__
# allows included file to know where it is in relation to includer.
# caching of included makefile is allowed if $(2)!contents is defined as the 
contents of the makefile.
# $(1) is the file to be included
include-makefile = $(foreach \
  m, \
  $(1), \
  $(eval $(call _include-makefile,include,$(m),$(__FILE__))))


If the file's corresponding !contents macro is defined, it the macro just 
eval's it.  Usually, the !contents macro is defined within the file itself.

HTH,
Noel