.gitignore

@@ -1,4 +1,5 @@
 .rebar3
+gajumaru
 _build
 _checkouts
 _vendor

Makefile

@@ -14,23 +14,20 @@ all: compile
 
 init: submodules
 
-submodules:
+submodules: gajumaru
 	git submodule init
 	git submodule update
+	ln -sfn $(GAJUMARU_LIB) gajumaru
 
 compile:
 	rebar3 compile
 
-build-my-plugin: compile
-	rebar3 gm_plugin
-
 # adapted from gmp_ix
-build-gm-with-my-plugin: build-my-plugin
+build-gm-with-my-plugin: init compile
 	cp _build/default/$(APP_NAME).ez $(GAJUMARU_LIB)/plugins
 	cd $(GAJUMARU_LIB) && make prod-build
 	cp -rvf gmconfig/$(TARGET_NETWORK)/gajumaru/* $(BUILD_DIR)
 
-
 fresh-console: build-gm-with-my-plugin console
 
 console:

README.md

@@ -21,12 +21,15 @@ make fresh-console
 ```
 
 ```
-(gajumaru@localhost)1> gmplugin_hello_app:hello().
+(gajumaru@localhost)1> gmplugin_hello:hello().
 "hello, world"
-(gajumaru@localhost)2> gmplugin_hello_app:network_id().
+(gajumaru@localhost)2> gmplugin_hello:network_id().
 <<"localnet">>
-(gajumaru@localhost)3> gmplugin_hello_app:height().
+(gajumaru@localhost)3> gmplugin_hello:height().
 {ok,1}
+(gajumaru@localhost)4> gmplugin_hello:top_block_hash().
+<<180,29,45,232,36,109,241,141,132,206,55,120,13,156,229,
+  68,76,166,229,246,220,199,45,20,244,161,153,164,72,...>>
 ```
 
 

rebar.config

@@ -1,16 +1,35 @@
+%%% -*- mode: erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
 {erl_opts, [debug_info]}.
 
-% there's some bug somewhere... this list must be nonempty for some reason
+%% When we want to use dependencies that are already in the gajumaru
+%% code base, we use the `{gm, App}` notation. The build plugin will
+%% consult the rebar.lock file of the gajumaru root and fetch the
+%% right version of `App`.
+%%
 {deps, [
     {gmserialization, {gm, gmserialization}}
 ]}.
 
-{project_apps_dir, "lib/gajumaru/apps"}.
+{plugins,
+ [
+  {gmplugin_rebar3,
+   {git, "https://git.qpq.swiss/QPQ-AG/gmplugin_rebar3.git",
+    {branch,"master"}}}
+ ]}.
 
-{plugins, [
-           {gmplugin_rebar3, {git, "https://git.qpq.swiss/QPQ-AG/gmplugin_rebar3.git", {branch,"master"}}}
-          ]}.
+%% These provider hooks inform the gmplugin_rebar3 provider.
+%% The pre-erlc_compile hook is needed if our code includes .hrl files
+%% from the gajumaru core (which it does, for demo purposes).
+%% The post-compile hook produces the packaged plugin.
+%%
+{provider_hooks, [
+    {pre,  [{erlc_compile, gm_setup}]},
+    {post, [{compile, gm_plugin}]}
+]}.
 
+%% This gajumaru root is used unless we run `make init`, which updates the
+%% submodules and creates a top-level symlink to lib/gajumaru.
+%%
 {gajumaru_root, {git, "https://git.qpq.swiss/QPQ-AG/gajumaru", "master"}}.
 
 

src/gmplugin_hello.erl

@@ -0,0 +1,37 @@
+%%% -*- mode:erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
+-module(gmplugin_hello).
+
+-export([
+         hello/0,
+         network_id/0,
+         height/0,
+         top_block_hash/0
+]).
+
+%% When including a .hrl file from the gajumaru core, we simply give
+%% the name (not -include_lib(), as this would require us to build
+%% the code base first.) The build plugin ensures that all core
+%% includes are available in the compiler's include path.
+%%
+-include("blocks.hrl").
+
+-spec hello() -> string().
+hello() ->
+    "hello, world".
+
+-spec network_id() -> binary().
+network_id() ->
+    aec_governance:get_network_id().
+
+
+-spec height() -> {ok, Height :: pos_integer()}
+                | {error, no_top_block}.
+height() ->
+    case aec_chain:top_height() of
+        undefined -> {error, no_top_block};
+        Height    -> {ok, Height}
+    end.
+
+-spec top_block_hash() -> block_header_hash().
+top_block_hash() ->
+    aec_chain:top_block_hash().

src/gmplugin_hello_app.erl

@@ -10,42 +10,8 @@
 
 -export([start/2, stop/1]).
 
-% tests
--export([
-    hello/0,
-    network_id/0,
-    height/0
-]).
-
 start(_StartType, _StartArgs) ->
     gmplugin_hello_sup:start_link().
 
 stop(_State) ->
     ok.
-
-%% internal functions
-
-
-%%
--spec hello() -> string().
-
-hello() ->
-    "hello, world".
-
-
-
--spec network_id() -> binary().
-
-network_id() ->
-    aec_governance:get_network_id().
-
-
-
--spec height() -> {ok, Height :: pos_integer()}
-                | {error, no_top_block}.
-
-height() ->
-    case aec_chain:top_height() of
-        undefined -> {error, no_top_block};
-        Height    -> {ok, Height}
-    end.