RE: .SECONDEXPAND and spaces?

[Leeuwesteijn,Joost]

Sorry about the messed up newlines. Quick fix to improve readability below.

Is there a big performance penalty when putting .SECONDEXPANSION at the top
of my (toplevel) makefile? Probably not in my small project, but in general.
Could it be a problem in large project? I suppose not because the files will
be loaded to memory only once; it's all done in memory which shouldn't
really make a big difference.

Could .SECONDEXPANSION have any other unwanted side-effects I should worry
about?


> -----Original Message-----
> 
> When I try to do secondary expansion, it seems to work. 
> Adding a simple string to the target name:
>     $(MOD1.OBJECTS) : address@hidden
> gives a make -p output of:
>     OUTPUT/MOD1/mod1file2.o: OUTPUT/MOD1/mod1file2.o-fubar 
> Which is OK.
> 
> 
> When I try to mangle the prerequisite a bit more (just a  test)
> it doesn't seem to work:
>     $(MOD1.OBJECTS) : $(MOD1.SOURCEDIR)/$$(notdir $$@)
> gives a make -p output of:
>     OUTPUT/MOD1/mod1file1.o: MOD1/$(notdir) MOD1/$($@)
> Which is not what I expected.
> 
> 
> The example from the manual (slightly modified):
>     $(MOD1.OBJECTS) : $$(patsubst %.o,%.c,$$@)
> results in a make -p of:
>     OUTPUT/MOD1/mod1file1.o: $(patsubst)
$(%.o,%.c,OUTPUT/MOD1/mod1file1.o)
> 
> 
> The next line:
>     $(MOD1.OBJECTS) : $(MOD1.OBJECTS) : $$(@:.o=.c)
> even results in a:
>     *** target pattern contains no `%'.  Stop.
> 
> Am I missing something? Do the spaces mess things up? But the 
> manual uses patsubst though...
> 
> --
> Joost Leeuwesteijn
> 
> ##########################################
> #
> # Test makefile
> #
> ##########################################
> 
> MOD1.SOURCEDIR:=./MOD1
> MOD1.OUTPUTDIR:=./OUTPUT/MOD1
> 
> # force immediate expansion of += lines
> MOD1.OBJECTS :=
> MOD1.OBJECTS += $(MOD1.OUTPUTDIR)/mod1file1.o
> MOD1.OBJECTS += $(MOD1.OUTPUTDIR)/mod1file2.o
> 
> # ----------------------------------------
> 
> $(MOD1.OUTPUTDIR)/module1.a : $(MOD1.OBJECTS)
> 
> .SECONDEXPANSION :
> $(MOD1.OBJECTS) : $(MOD1.SOURCEDIR)/$$(notdir $$@)
> #$(MOD1.OBJECTS) : address@hidden
> #$(MOD1.OBJECTS) : $$(@:.o=.c)
> #$(MOD1.OBJECTS) : $$(patsubst %.o,%.c,$$@)
> 
> # ----------------------------------------
> 
> %.a :
>       @echo "Linking $@"
>       @echo "     $?"
>       @touch $@
> 
> %.o : %.c
>       @echo "Compiling $@"
>       @touch $@