Re: make Eval function / factoring out analagous rules & variables

[Markus Mauhart]

"Alister Shipman" <address@hidden> wrote ...
>
> - So far I try and define these "dynamically"
> generated macros by:
>
> define PATTERN_MATCH_MACROS
> $(1)_CCOBJS = $${$(1)_CCSRCS:.cc=.o}
> endef
>
> $(foreach library, $(LIBRARY_LIST), $(eval $(call
> PATTERN_MATCH_MACROS,$(library))))
>
> But when it gets to the rules - even when they are
> just typed in (as opposed to generated) i.e
> libsl_dbtypes.a : $(dbtypes_CCOBJS)
>
> it claims there are no pre-requisites for
> libsl_dbtypes.a - and when I try an origin call on
> dbtypes_CCOBJS it reports it as undefined.

IMHO what you did wrong was to use variables inside the
foreach that havnt still got their value:
your foreach ultimately expands to multiple rules, and both
targets & prerequisites of rules are dereferenced
immediately (before your later variable assignments come).


The following for me works as expected:

* make.3.80 made and run under cygwin

* Current dir contains makefile & 11.cpp & 12.cpp.

* makefile:
---------------------
# (1) target specific variables
PROGS += A
A_SRCS = 11.cpp 12.cpp

PROGS += B
B_SRCS = 11.cpp

# (2) templates to construct other variables & rules from target-name:
define PROG_FROM_SRCS
$(1)_OBJS := $($(1)_SRCS:.cpp=.o)
$(1).exe : $$($(1)_OBJS)
    @echo building "$$@" from "$$^"
endef

# (3) instantiate NOW the rule-template for all current PROGS:
# This part MUST come AFTER (1&2). Order of (1&2) is irrelevant.
$(foreach prog,$(PROGS),$(eval $(call PROG_FROM_SRCS,$(prog))))

# (4) misc
.SUFFIXES: .cpp .o

%.o : %.cpp
    @echo Building "$@" from "$^"
-----------------------

* test it:
$ make A.exe
echo Building "11.o" from "11.cpp"
echo Building "12.o" from "12.cpp"
echo building "A.exe" from "11.o 12.o"

$ make B.exe
echo Building "11.o" from "11.cpp"
echo building "B.exe" from "11.o"


A little simpler version of the makefile (diff = (**)):
* makefile:
---------------------
# (1) target specific variables
PROGS += A
A_SRCS = 11.cpp 12.cpp

PROGS += B
B_SRCS = 11.cpp

# (2) templates to construct other variables & rules from target-name:
define PROG_FROM_SRCS_2
$(prog)_OBJS := $($(prog)_SRCS:.cpp=.o)
$(prog).exe : $$($(prog)_OBJS)
    @echo building "$$@" from "$$^"
endef

# (3) instantiate NOW the rule-template for all current PROGS:
# This part MUST come AFTER (1&2). Order of (1&2) is irrelevant.
$(foreach prog,$(PROGS),$(eval $(PROG_FROM_SRCS_2))) #(**)

# (4) misc
.SUFFIXES: .cpp .o

%.o : %.cpp
    @echo Building "$@" from "$^"
-----------------------