On Sun, 22 May 2016 00:19:49 +0100
aidecoe@gentoo.org wrote:

> From: Amadeusz Żołnowski <aidecoe@gentoo.org>
> 
> It is an eclass providing functions to build Erlang/OTP projects using
> dev-util/rebar. All packages in upcoming category dev-erlang are going
> to use this eclass.
> ---
>  eclass/rebar.eclass | 223 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 223 insertions(+)
>  create mode 100644 eclass/rebar.eclass
> 
> diff --git a/eclass/rebar.eclass b/eclass/rebar.eclass
> new file mode 100644
> index 0000000..1a4eaba
> --- /dev/null
> +++ b/eclass/rebar.eclass
> @@ -0,0 +1,223 @@
> +# Copyright 1999-2016 Gentoo Foundation
> +# Distributed under the terms of the GNU General Public License v2
> +# $Id$
> +
> +# @ECLASS: rebar.eclass
> +# @MAINTAINER:
> +# Amadeusz Żołnowski <aidecoe@gentoo.org>
> +# @AUTHOR:
> +# Amadeusz Żołnowski <aidecoe@gentoo.org>
> +# @BLURB: Build Erlang/OTP projects using dev-util/rebar.
> +# @DESCRIPTION:
> +# An eclass providing functions to build Erlang/OTP projects using
> +# dev-util/rebar.
> +#
> +# rebar is a tool which tries to resolve dependencies itself which is by
> +# cloning remote git repositories. Dependant projects are usually expected to
> +# be in sub-directory 'deps' rather than looking at system Erlang lib
> +# directory. Projects relying on rebar usually don't have 'install' make
> +# targets. The eclass workarounds some of these problems. It handles
> +# installation in a generic way for Erlang/OTP structured projects.
> +
> +case "${EAPI:-0}" in
> +	0|1|2|3|4|5)
> +		die "Unsupported EAPI=${EAPI:-0} (too old) for ${ECLASS}"
> +		;;
> +	6)
> +		;;
> +	*)
> +		die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
> +		;;
> +esac
> +
> +EXPORT_FUNCTIONS src_prepare src_compile src_install
> +
> +RDEPEND="dev-lang/erlang"
> +DEPEND="${RDEPEND}
> +	dev-util/rebar
> +	>=sys-apps/gawk-4.1"
> +
> +# @ECLASS-VARIABLE: REBAR_APP_SRC
> +# @DESCRIPTION:
> +# Relative path to .app.src description file.
> +REBAR_APP_SRC="${REBAR_APP_SRC-src/${PN}.app.src}"
> +
> +# @FUNCTION: get_erl_libs
> +# @RETURN: the path to Erlang lib directory
> +# @DESCRIPTION:
> +# Get the full path without EPREFIX to Erlang lib directory.
> +get_erl_libs() {
> +	echo "/usr/$(get_libdir)/erlang/lib"
> +}
> +
> +# @FUNCTION: _rebar_find_dep
> +# @INTERNAL
> +# @USAGE: <project_name>
> +# @RETURN: full path with EPREFIX to a Erlang package/project on success,
> +# code 1 when dependency is not found and code 2 if multiple versions of
> +# dependency are found.
> +# @DESCRIPTION:
> +# Find a Erlang package/project by name in Erlang lib directory. Project
> +# directory is usually suffixed with version. It is matched to '<project_name>'
> +# or '<project_name>-*'.
> +_rebar_find_dep() {
> +	local pn="$1"
> +	local p
> +	local result
> +
> +	pushd "${EPREFIX}$(get_erl_libs)" >/dev/null || return 1
> +	for p in ${pn} ${pn}-*; do
> +		if [[ -d ${p} ]]; then
> +			# Ensure there's at most one matching.
> +			[[ ${result} ]] && return 2
> +			result="${p}"
> +		fi
> +	done
> +	popd >/dev/null || die
> +
> +	[[ ${result} ]] || return 1
> +	echo "${result}"
> +}
> +
> +# @FUNCTION: erebar
> +# @USAGE: <targets>
> +# @DESCRIPTION:
> +# Run rebar with verbose flag. Die on failure.
> +erebar() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	(( $# > 0 )) || die "erebar: at least one target is required"
> +
> +	local -x ERL_LIBS="${EPREFIX}$(get_erl_libs)"
> +	rebar -v skip_deps=true "$@" || die "rebar $@ failed"

Maybe 'die -n', for consistency with emake?

> +}
> +
> +# @FUNCTION: rebar_fix_include_path
> +# @USAGE: <project_name>
> +# @DESCRIPTION:
> +# Fix path in rebar.config to 'include' directory of dependant project/package,
> +# so it points to installation in system Erlang lib rather than relative 'deps'
> +# directory.
> +#
> +# The function dies on failure.
> +rebar_fix_include_path() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	local pn="$1"
> +	local erl_libs="${EPREFIX}$(get_erl_libs)"
> +	local p
> +
> +	p="$(_rebar_find_dep "${pn}")" \
> +		|| die "failed to unambiguously resolve dependency of '${pn}'"
> +
> +	gawk -i inplace \
> +		-v erl_libs="${erl_libs}" -v pn="${pn}" -v p="${p}" '
> +/^{[[:space:]]*erl_opts[[:space:]]*,/, /}[[:space:]]*\.$/ {
> +	pattern = "\"(./)?deps/" pn "/include\"";
> +	if (match($0, "{i,[[:space:]]*" pattern "[[:space:]]*}")) {
> +		sub(pattern, "\"" erl_libs "/" p "/include\"");
> +	}
> +	print $0;
> +	next;
> +}
> +1
> +' rebar.config || die "failed to fix include paths in rebar.config for '${pn}'"
> +}
> +
> +# @FUNCTION: rebar_remove_deps
> +# @DESCRIPTION:
> +# Remove dependencies list from rebar.config and deceive build rules that any
> +# dependencies are already fetched and built. Otherwise rebar tries to fetch
> +# dependencies and compile them.
> +#
> +# The function dies on failure.
> +rebar_remove_deps() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	mkdir -p "${S}/deps" && :>"${S}/deps/.got" && :>"${S}/deps/.built" || die
> +	gawk -i inplace '
> +/^{[[:space:]]*deps[[:space:]]*,/, /}[[:space:]]*\.$/ {
> +	if ($0 ~ /}[[:space:]]*\.$/) {
> +		print "{deps, []}.";
> +	}
> +	next;
> +}
> +1
> +' rebar.config || die "failed to remove deps from rebar.config"
> +}
> +
> +# @FUNCTION: rebar_set_vsn
> +# @USAGE: [<version>]
> +# @DESCRIPTION:
> +# Set version in project description file if it's not set.
> +#
> +# <version> is optional. Default is PV stripped from version suffix.
> +#
> +# The function dies on failure.
> +rebar_set_vsn() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	local version="${1:-${PV%_*}}"
> +
> +	sed -e "s/vsn, git/vsn, \"${version}\"/" \
> +		-i "${S}/${REBAR_APP_SRC}" \
> +		|| die "failed to set version in src/${PN}.app.src"
> +}
> +
> +# @FUNCTION: rebar_src_prepare
> +# @DESCRIPTION:
> +# Prevent rebar from fetching in compiling dependencies. Set version in project

I think this sentence is incorrect.

> +# description file if it's not set.
> +#
> +# Existence of rebar.config is optional, but file description file must exist
> +# at 'src/${PN}.app.src'.
> +rebar_src_prepare() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	default
> +	rebar_set_vsn
> +	[[ -f rebar.config ]] && rebar_remove_deps
> +}
> +
> +# @FUNCTION: rebar_src_configure
> +# @DESCRIPTION:
> +# Configure with ERL_LIBS set.
> +rebar_src_configure() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	local -x ERL_LIBS="${EPREFIX}$(get_erl_libs)"
> +	default
> +}
> +
> +# @FUNCTION: rebar_src_compile
> +# @DESCRIPTION:
> +# Compile project with rebar.
> +rebar_src_compile() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	erebar compile
> +}
> +
> +# @FUNCTION: rebar_src_install
> +# @DESCRIPTION:
> +# Install BEAM files, include headers, executables and native libraries.
> +# Install standard docs like README or defined in DOCS variable.
> +#
> +# Function expects that project conforms to Erlang/OTP structure.
> +rebar_src_install() {
> +	debug-print-function ${FUNCNAME} "${@}"
> +
> +	local bin
> +	local dest="$(get_erl_libs)/${P}"
> +
> +	insinto "${dest}"
> +	doins -r ebin
> +	[[ -d include ]] && doins -r include
> +	[[ -d bin ]] && for bin in bin/*; do dobin "$bin"; done
> +
> +	if [[ -d priv ]]; then
> +		cp -pR priv "${ED}${dest}/" || die "failed to install priv/"
> +	fi
> +
> +	einstalldocs
> +}

I think I have no further comments, so the two things above considered,
looks good to go.

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>