GNU Make for loop with two variables

问题

I want to write something along these lines:

$(foreach (var1, var2), ($(LIST1), $(LIST2)), cp $(var1) $(var2);)

How do I go about doing this in a GNU makefile?

回答1:

Beta's suggestion to use join is on the right track, but the problem is that it's not so easy to use it in a way that constructs a command line containing whitespace, such as the one you originally wanted:

$(foreach (var1, var2), ($(LIST1), $(LIST2)), cp $(var1) $(var2);)

because join joins words together: it was originally intended for constructing filenames. However you can play a trick; here's an example of a way to use join that gives you the output you are looking for:

$(subst ^, ,$(join $(addprefix cp^,$(LIST1)),$(patsubst %,^%;,$(LIST2))))

If you think your lists might contain ^ characters then choose something else. Let me know if you need this unpacked/explained.

回答2:

LIST1 := a b c
LIST2 := 1 2 3

# outside a rule:
$(foreach var1, a b c, $(foreach var2, 1 2 3, $(info $(var1)_$(var2))))

# inside a rule: first line starts with a TAB, all the rest are spaces
all:
    @for x in $(LIST1);\
    do \
      for y in $(LIST2);\
      do\
        echo $$x $$y; \
      done \
    done

(Please note that a nested loop that does cp doesn't make much sense.)

EDIT:
Well why didn't you say so?

LIST3 := $(join $(LIST1),$(LIST2))

回答3:

This is a good candidate for gsml (GNU Make Standard Library). You can include it by putting the files __gmsl and gml in the current directory (or in /usr/gnu/include, /usr/local/include/ etc.) and adding the line include gsml in your Makefile. It includes the pairmap function, which does exactly what you want (i.e. zipWith).

include gmsl
cp2 = cp $1 $2;
zip = $1 : $2
$(LIST2):
    @echo $(call pairmap, zip, $(LIST1), $(LIST2))
    $(call pairmap, cp2, $(LIST1), $(LIST2))

Outputs

$ make 
A : 1 B : 2 C : 3 D : 4
cp A 1; cp B 2; cp C 3; cp D 4;

来源：https://stackoverflow.com/questions/9622606/gnu-make-for-loop-with-two-variables

标签

makefile

gnu