#
# MAKE_LONG_LIST:
#
# MAKE function to be called when a long variable list needs to be
# put into a file with one item on each line.
# Two arguments:
# $(1) = list name
# $(2) = MAKE variable to put into list
#
# The resulting list can be used in combination with xargs to get
# around shell command-line character-length restrictions.
#
# The current hack is encapsulated in a separate included Makefile
# to hide the confusing recursive function.
#
# RECURSIVE version is requires GNU make-3.80 or higher, but is shorter and
# will handle any size list.
#

# CALC:
# Math helper function -- Use shell to do simple operations.
# Relies on ksh/bash $(( )) syntax.
# If you don't like this or need something more portable, change to
# CALC = $(shell echo "$(1)" | bc)
CALC = $(shell echo $$(($(1))))

nextindx = $(call CALC,$(3)+1)
nextword = $(word $(nextindx),$(2))
nextlist = $(wordlist $(nextindx),$(words $(2)),$(2))

# ADD_TO_LIST:
# A recursive function definition to handle iteration
# ARG 1 = filename to contain list, one entry per line
# ARG 2 = variable containing a very long list
# ARG 3 = Increment
define ADD_TO_LIST
	@printf "%s\n" $(wordlist 1,$(3),$(2)) >> $(1)
	$(if $(nextword),$(call ADD_TO_LIST,$(1),$(nextlist),$(3)),@echo)
endef

# Actual MAKE_LONG_LIST definition is a wrapper around the recursive call.
# Note that the list file is first cleared out using Bourne/ksh/bash syntax.
# I just arbitrarily set the iteration size to 500, but you can make it
# smaller if the system environment length is still too large.
define MAKE_LONG_LIST
	: > $(1)
	$(call ADD_TO_LIST,$(1),$(2),500)
endef