glib2: Compile schemas per directory (#1881)

* glib2: Compile schemas per directory

By changing GSETTINGSSCHEMADIR during the build setup or on single tasks
or generators, the user may place schemas in various locations. Adding a
post build function for each of this location compiles all of them
instead of only one global directory.

* glib2: Notify user about failed schema compilation

* glib2: Demo schemas installed to multiple places

A new schema lacking lacking any enumerations was introduced. Installing
it isolated simplifies the generator creation to the essential
components demonstrated.

demos/glib2/org.gsettings.simple.gschema.xml

@@ -0,0 +1,7 @@
+<schemalist>
+  <schema id="org.gsettings.simple">
+    <key name="greeting" type="s">
+      <default>"Hello, world"</default>
+    </key>
+  </schema>
+</schemalist>

demos/glib2/wscript

@@ -8,6 +8,8 @@ APPNAME='glib2_test'
 top = '.'
 out = 'build'
 
+import os
+
 def options(opt):
 	opt.load ('compiler_c glib2')
 
@@ -46,3 +48,10 @@ def build(bld):
 		source   = 'org.glib2.test.gresource.xml',
 		install_path = 'lib/glib2_test'
 	)
+
+	# Install a schema to a different location.
+	# It will be compiled to a cache file besides it.
+	bld(
+		features = 'glib2',
+		settings_schema_files = ['org.gsettings.simple.gschema.xml']
+	).env.GSETTINGSSCHEMADIR = os.path.join('etc', 'glib-2.0', 'schemas')

waflib/Tools/glib2.py

@@ -12,6 +12,7 @@ Support for GLib2 tools:
 """
 
 import os
+import functools
 from waflib import Context, Task, Utils, Options, Errors, Logs
 from waflib.TaskGen import taskgen_method, before_method, feature, extension
 from waflib.Configure import conf
@@ -303,25 +304,28 @@ def process_settings(self):
 	def compile_schemas_callback(bld):
 		if not bld.is_install:
 			return
-		env = bld.env
+		compile_schemas = Utils.to_list(bld.env.GLIB_COMPILE_SCHEMAS)
 		destdir = Options.options.destdir
+		paths = bld._compile_schemas_registered
 		if destdir:
-			path = os.path.join(destdir, env.GSETTINGSSCHEMADIR.lstrip(os.sep))
-		else:
-			path = env.GSETTINGSSCHEMADIR
-		Logs.pprint('YELLOW', 'Updating GSettings schema cache %r' % path)
-		command = Utils.to_list(env.GLIB_COMPILE_SCHEMAS) + [path]
-		self.bld.exec_command(command)
+			paths = (os.path.join(destdir, path.lstrip(os.sep)) for path in paths)
+		for path in paths:
+			Logs.pprint('YELLOW', 'Updating GSettings schema cache %r' % path)
+			if self.bld.exec_command(compile_schemas + [path]):
+				Logs.warn('Could not update GSettings schema cache %r' % path)
 
 	if self.bld.is_install:
-		if not self.env.GSETTINGSSCHEMADIR:
+		schemadir = self.env.GSETTINGSSCHEMADIR
+		if not schemadir:
 			raise Errors.WafError ('GSETTINGSSCHEMADIR not defined (should have been set up automatically during configure)')
 
 		if install_files:
-			self.add_install_files(install_to=self.env.GSETTINGSSCHEMADIR, install_from=install_files)
-			if not hasattr(self.bld, '_compile_schemas_registered'):
+			self.add_install_files(install_to=schemadir, install_from=install_files)
+			registered_schemas = getattr(self.bld, '_compile_schemas_registered', None)
+			if not registered_schemas:
+				registered_schemas = self.bld._compile_schemas_registered = set()
 				self.bld.add_post_fun(compile_schemas_callback)
-				self.bld._compile_schemas_registered = True
+			registered_schemas.add(schemadir)
 
 class glib_validate_schema(Task.Task):
 	"""