Move templates outside the source .mk filestemplates

Templates now no longer use Make variables for substitution
but instead replace strings with their equivalent:

  template_name: Corresponds to n=template_name
  project_name:  Corresponds to $(PROJECT) or in=project_name

This allows defining templates outside of Makefiles. For
example an external plugin could define their templates
in templates/my_template.erl and then have the following
in the included Makefile:

  tpl_my_template = $(file < $(THIS)/templates/my_template.erl)

By default the created file will be in src/template_name.erl.
This can be overriden with the tplp_* variable:

  tplp_my_template = src/model/my_template.erl

Substitution is applied both to the template contents and
to its path.

In addition, attempting to overwrite an existing file when
creating a template will result in failure.

1 files changed, 10 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index f6d4287..b69bfb8 100644
--- a/Makefile
+++ b/Makefile
@@ -29,7 +29,7 @@ ERLANG_MK_VERSION = $(shell git describe --dirty --tags --always)
 
 .PHONY: all check
 
-all:
+all: templates.mk
 # Temporarily force the printing of the CHANGELOG.
 # The required variable hadn't been introduced yet.
 #ifdef UPGRADE
@@ -40,6 +40,15 @@ all:
 		| sed 's/^ERLANG_MK_VERSION =.*/ERLANG_MK_VERSION = $(ERLANG_MK_VERSION)/' \
 		| sed 's:^ERLANG_MK_WITHOUT =.*:ERLANG_MK_WITHOUT = $(WITHOUT):' > $(ERLANG_MK)
 
+# Templates that end with .erl have the suffix removed. It is implied.
+templates.mk: Makefile templates/*
+	for f in templates/*; do \
+		echo define tpl_`basename $$f .erl`; \
+		cat $$f; \
+		echo endef; \
+		echo; \
+	done > $@
+
 lint: all
 	$(MAKE) -f erlang.mk --warn-undefined-variables