[SOLVED] How to replace entries of a makefile variable

Issue

I have a variable MY_VAR inside a Makefile defined as MY_VAR = read orange yellow blue green white black. I am trying to write a Makefile function/macro that takes a list of colors as input and replaces them by appending a suffix to them. Inside the Makefile I can do this as MY_NEW_VAR = $(shell echo $(MY_VAR) | sed -e 's/black/blackcolor/' -e 's/red/redcolor/' -e 's/white/whitecolor/') but running into problems when doing this using a function with for loop.

define append_color
for color in $(2); do \
  $(eval $(1) += $(shell echo $(MY_VAR) | sed 's/$$color/$$color$(3)/')); \
done;      
endef  

Here $2 is the list of colors to replace and $(1) will contain the result and $3 contains the suffix to append. Below is the function call inside Makefile:

MY_VAR = read orange yellow blue green white black
$(call append_color,MY_NEW_VAR,black red white,color)    

The makefile returns the following error at the point of call to this function inside the Makefile:

Makefile.mk:50: *** missing separator.  Stop.  

Any suggestions on what I am missing or alternatives for doing the same ?

Thanks

Solution

There are several ways how you can accomplish your task: Using the classical patsubst function:

append_color = $(patsubst %,%$(3),$(filter $(2),$(1))) $(filter-out $(2),$(1))
MY_NEW_VAR := $(call append_color,$(MY_VAR),black red white,color)

Or with foreach:

append_color = $(foreach w,$(1),$(if $(filter $(w),$(2)),$(w)$(3),$(w)))
MY_NEW_VAR := $(call append_color,$(MY_VAR),black red white,color)

Answered By - Vroomfondel