[erlang-questions] Makefile detecting / downloading rebar

[Michael Santos]

On Sun, Jul 22, 2012 at 01:08:15PM +0200, Gleb Peregud wrote:
> Hello all
> 
> Just an idea. Do you think this is a good approach to put the
> following into a makefile of an open source library?
> 
> all: rebar
> 	./rebar compile
> 
> rebar:
> 	which rebar && ln -sf `which rebar` || true
> 	test -x ./rebar || (wget
> http://cloud.github.com/downloads/basho/rebar/rebar && chmod u+x
> rebar)
> 
> This allows user who has rebar installed globally to still use it, but
> for users who prefer local rebar binaries to download it
> automatically. Can this script be improved?

You could download rebar using erlang rather than wget:

# shell is GNU makefile only syntax
REBAR=$(shell which rebar || echo ./rebar)

./rebar:
    erl -noshell -s inets start -s ssl start \
        -eval 'httpc:request(get, {"https://github.com/downloads/basho/rebar/rebar", []}, [], [{stream, "./rebar"}])' \
        -s inets stop -s init stop
    chmod +x ./rebar