makefile: find a position of word in a variable

Question

In my makefile, I need to make a variable assignment based on a command line variable value. for example, I do:

make var_1=xxx

where

Answer 1

This works in mingw gnu make 4.3 :

define get_index
$(shell \
    $(eval _c = 1)\
    $(eval _b = n n) \
    $(foreach x,$(2), \
        $(eval _b += n \
        $(eval _c = $(words $(_b)) \
        $(if $(filter $(1),$(x)), \
            $(eval _r = $(_c)))))) \
            echo $(_r) \
    $(eval _c =) \
    $(eval _b =) \
    $(eval _r =) \
)
endef

Takes two arguments; the word to search for and the list where to search. The index is 'returned' by echoing in $(shell ...)

Example:

list = cow horse chicken
index = $(call get_index,horse,$(list))
@echo $(index)

# output: 2