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GNU make: function $(foreach …)

$(foreach  var,list,text)

The following example iterates over each word in $(list).

In each iteration, first the variable with the name word is set to the value of the word of the iteration, and then, the text $(word)-$(word) is expanded.

Thus, this makefile prints foo-foo bar-bar baz-baz when invoked.

list = foo bar baz
list_2 = $(foreach word,$(list),$(word)-$(word))

all:
	@echo $(list_2)

Github repository about-Makefile, path: /functions/foreach/double-words.mak

Of course, calls to $(foreach) can be nested:

bla      = foo bar baz
list_foo = ding dong
list_bar = one two three
list_baz = XXX

cross_product = $(foreach T, $(bla),   \
	$(foreach U, $(list_$T),             \
	   $T\,$U                            \
	)                                    \
)

all:
	@echo $(cross_product)

Github repository about-Makefile, path: /functions/foreach/nested.mak

When invoked, the above makefile prints foo,ding foo,dong bar,one bar,two bar,three baz,XXX.

GNU make: function $(foreach …)

See also