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Re: Idea: Allow $(name ...) as an abbrevation of $(call name ....)

From: Masahiro Yamada
Subject: Re: Idea: Allow $(name ...) as an abbrevation of $(call name ....)
Date: Fri, 14 Jun 2019 11:12:16 +0900

On Fri, Jun 14, 2019 at 4:16 AM Tim Murphy <address@hidden> wrote:
> builtin functions can check their arguments to some extent. Interesting to 
> wonder if user defined ones can.
> we don't even have $(equals) or a way to know the number of arguments that 
> were supplied or any mathematical operations with which to compare. So when 
> something is called wongly it charges on to the end, evaluating blindly to 
> who knows what and we can spend hours trying to tease out the cause of a 
> missing compiler option .... but.....we are focused on the saving of a tiny 
> bit of typing.

You can check the number of arguments for user-defined functions if you like.

-------------------(sample code)----------------------
# my-dummy takes 1 or 2 arguments
my-dummy = $(if $(1),,$(error too few arguments))$(if $(3),$(error too
many arguments))echo $(1) $(2)

        @$(call my-dummy)

        @$(call my-dummy,hello)

        @$(call my-dummy,hello,world)

        @$(call my-dummy,see,you,later)
-------------------(sample code end)----------------------

$ make test1
Makefile:4: *** too few arguments.  Stop.
$ make test2
$ make test3
hello world
$ make test4
Makefile:13: *** too many arguments.  Stop.

If it is tedious to duplicate this check for every user-defined function,
you can macrofy it.

-------------------(sample code 2)----------------------
# Usage: $(eval $(call arg-check,min,max-1))
arg-check = $$(if $$($(1)),,$$(error too few arguments))$$(if
$$($(2)),$$(error too many arguments))

my-dummy = $(eval $(call arg-check,1,3))echo $(1) $(2)
-------------------(sample code 2 end)----------------------

Best Regards
Masahiro Yamada

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