Geek Answers Handbook

Definition of variables in the macro of a makefile (definition)

I use defineto create a macro. However, in the define constructor, I cannot create a variable. Assigning a variable does not cause an error, but when I try to use it a bit later, its value is empty.

for instance

#######################################################
## JIDL_RULE
## Macro to build and install PHP and JS files 
## from idl.json files
#######################################################
## param $(1) Full path to idl.json file
## param $(2) Path to directory to copy PHP file into (relative to where make is run from)
## param $(3) Path to directory to copy JS file into (relative to where make is run from)
##########################################################
define JIDL_RULE
# Create the output directory if it doesn't exist
$(2):
    mkdir -p $(2)

$(3):
    mkdir -p $(3)

# Rule to generate a PHP file. Notice that we have to prepend `pwd`
$(call GENERATED_FILE,$(1),$(2),php): $(1)
    $(PHPHOME)/bin/php -f $(JIDL2PHP) -- `pwd`/$$< $(DATADEF_HOME) > $$@

# Rule to generate a JS file
$(call GENERATED_FILE,$(1),$(3),js): $(1)
    $(PHPHOME)/bin/php -f $(JIDL2JS) -- `pwd`/$$< $(DATADEF_HOME) > $$@

# Add those generated files to the all target
all:: $(call GENERATED_FILE,$(1),$(2),php) $(call GENERATED_FILE,$(1),$(3),js) $(2) $(3)

# Remove generated files on clean:
clean::
    -$(RM) -f $(call GENERATED_FILE,$(1),$(2),php) $(call GENERATED_FILE,$(1),$(3),js)

# Rules to install generated files
$(call PHP_RULE, $(call GENERATED_FILE,$(1),$(2),php))
$(call JS_RULE, $(call GENERATED_FILE,$(1),$(3),js))
endef

From the above code, you can see that I am duplicating the lines

$(call GENERATED_FILE,$(1),$(2),php)and $(call GENERATED_FILE,$(1),$(3),js)from several places. So I tried to create two variables as the first two macro statements, for example:

PHP_OUT_FILE := $(call GENERATED_FILE,$(1),$(2),php)
JS_OUT_FILE := $(call GENERATED_FILE,$(1),$(3),js)

But if I try to use them later (still within the definition), for example, $(PHP_OUT_FILE)or $(JS_OUT_FILE), the variables are empty. I would very much like to remove this duplication from my macro. Am I doing it wrong? Is it impossible? Is there any other way to do this?

TEST OF BOTH ANSWERS

, "". , , , , - ( ).

eriktous- , $$ , , $$ $ target. .

Ise Wisteria , , . eval , , , . , , .

makefile,

define TEST
$(eval INNERVAR := Blah $(1))
inner::
    echo Using EVAL: INNERVAR = $(INNERVAR)
    echo 

endef

define TEST2
INNERVAR2 := Blah $(1)
inner::
    echo Using  double dollar sign: INNERVAR2 = $$(INNERVAR2)
    echo 
endef

$(eval $(call TEST,TEST_1_A))
$(eval $(call TEST,TEST_1_B))
$(eval $(call TEST2,TEST_2_A))
$(eval $(call TEST2,TEST_2_B))

inner::
    echo is that var really private? $(INNERVAR) 
    echo is that var really private? $(INNERVAR2)

: make echoing , , .

Using EVAL: INNERVAR = Blah TEST_1_A

Using EVAL: INNERVAR = Blah TEST_1_B

# Calling the macro twice overwrites the global variable and since
# it not expanded immediately, calling the macro with different params
# will output the last value that we set the variable to
Using double dollar sign: INNERVAR2 = Blah TEST_2_B
Using double dollar sign: INNERVAR2 = Blah TEST_2_B

# As expected, the variables are not private to the macro.
is that var really private? Blah TEST_1_B
is that var really private? Blah TEST_2_B
+5
2

eval , :

$(eval PHP_OUT_FILE := $(call GENERATED_FILE,$(1),$(2),php))
$(eval JS_OUT_FILE := $(call GENERATED_FILE,$(1),$(3),js))

,

+10

, , , make . Ise Wisteria , , , . $ , : $$(PHP_OUT_FILE).

+5

More articles:


All Articles