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|
#
# local variables:
# o The keyword will make sure the variable is defined in
# current variable context instead of the global one.
# o Local variables are readable by children but not writable,
# writes goes to the globle space (a sideeffect / feature).
# o Local variables hides global and parent variables.
#
# global variable.
var_exists1 = 1
##
# A simple define that is $(eval)uated.
define def_test1
# check that the existing variable is accessible.
ifneq ($(var_exists1),1)
$(error var_exists1=$(var_exists1) (def_test1/1))
endif
# Quick check with a couple of local variables.
local var_local1 = 2
ifneq ($(var_local1),2)
$(error var_local1=$(var_local1) (def_test1/2))
endif
local var_local2 = 3
ifneq ($(var_local2),3)
$(error var_local2=$(var_local2) (def_test1/3))
endif
# var_local1 and var_local2 should remain unchanged, var_local3 shouldn't exist.
$(evalctx $(value def_test2))
ifneq ($(var_local1),2)
$(error var_local1=$(var_local1) (def_test1/4))
endif
ifneq ($(var_local2),3)
$(error var_local2=$(var_local2) (def_test1/5))
endif
ifneq ($(var_local3),)
$(error var_local3=$(var_local3) (def_test1/6))
endif
endef # def_test1
##
# Called by def_test1, this checks that the locals of def_test1
# are accessible and can be hidden by another local variable
# or updated if assigned to.
define def_test2
# check that the existing variables are accessible, including the def_test1 ones.
ifneq ($(var_exists1),1)
$(error var_exists1=$(var_exists1) (def_test2/1))
endif
ifneq ($(var_local1),2)
$(error var_local1=$(var_local1) (def_test2/2))
endif
ifneq ($(var_local2),3)
$(error var_local2=$(var_local2) (def_test2/3))
endif
# Make a local var_local1 that hides the one in def_test1.
local var_local1 = 20
ifneq ($(var_local1),20)
$(error var_local1=$(var_local1) (def_test2/4))
endif
# FEATURE: Update the var_local2 variable, this should be visible in the global space and not the local.
var_local2 = 30
ifneq ($(var_local2),3)
$(error var_local2=$(var_local2) (def_test2/5))
endif
# create a new local variable that isn't accessible from def_test1.
local var_local3 = 4
ifneq ($(var_local3),4)
$(error var_local3=$(var_local3) (def_test2/6))
endif
endef # def_test2
#
# The test body
#
# None of the local variables should exist.
ifneq ($(var_local1),)
$(error var_local1=$(var_local1))
endif
ifneq ($(var_local2),)
$(error var_local2=$(var_local2))
endif
ifneq ($(var_local3),)
$(error var_local3=$(var_local3))
endif
# Evaluate the function in a local context.
$(evalctx $(value def_test1))
# FEATURE: see var_local2 = 30 in def_test2.
ifneq ($(var_local2),30)
$(error var_local2=$(var_local2))
endif
# None of the other local variables should exist.
ifneq ($(var_local1),)
$(error var_local1=$(var_local1))
endif
ifneq ($(var_local3),)
$(error var_local3=$(var_local3))
endif
# dummy
all:
echo local variables works.
|
