add support for module ordering via config...

when a dictionary is missing a key, make sure it gets deleted when
test setting it...

casimport/__init__.py

@@ -22,6 +22,7 @@
 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 # SUCH DAMAGE.
 
+import configparser
 import contextlib
 import filecmp
 import functools
@@ -75,11 +76,19 @@ def tempset(obj, key, value):
 	'''
 
 	try:
-		oldvalue = obj[key]
+		dodelitem = False
+		if key in obj:
+			oldvalue = obj[key]
+		else:
+			dodelitem = True
+
 		obj[key] = value
 		yield
 	finally:
-		obj[key] = oldvalue
+		if not dodelitem:
+			obj[key] = oldvalue
+		else:
+			del obj[key]
 
 @contextlib.contextmanager
 def tempattrset(obj, key, value):
@@ -119,6 +128,10 @@ def urlfetch(url):
 		return req.read()
 
 class HTTPSCAS(object):
+	@classmethod
+	def fromconfig(cls, conf):
+		return cls()
+
 	def fetch_data(self, url):
 		if url.scheme != 'https':
 			raise ValueError('cannot handle scheme %s' %
@@ -131,6 +144,10 @@ class IPFSCAS(object):
 	gwhost = 'gateway.ipfs.io'
 	gwhost = 'cloudflare-ipfs.com'
 
+	@classmethod
+	def fromconfig(cls, conf):
+		return cls()
+
 	def make_url(self, url):
 		return urllib.parse.urlunparse(('https', self.gwhost,
 		    '/ipfs/' + url.netloc) + ('', ) * 3)
@@ -152,6 +169,10 @@ class FileDirCAS(object):
 		self._path.mkdir(exist_ok=True)
 		self._hashes = {}
 
+	@classmethod
+	def fromconfig(cls, conf):
+		return cls(os.path.expanduser(conf['path']))
+
 	def refresh_dir(self):
 		'''Internal method to refresh the internal cache of
 		hashes.'''
@@ -353,17 +374,33 @@ class CASFinder(MetaPathFinder, Loader):
 
 			exec(data, module.__dict__)
 
+_supportedmodules = {
+	'https': HTTPSCAS.fromconfig,
+	'ipfs': IPFSCAS.fromconfig,
+	'cache': FileDirCAS.fromconfig,
+}
+
 def defaultinit(casf):
 	basedir = pathlib.Path.home() / '.casimport'
 	basedir.mkdir(exist_ok=True)
 
-	conffile = basedir / 'casimport.conf'
+	conffile = pathlib.Path(os.environ.get('CASIMPORT_CONF', basedir / 'casimport.conf'))
 	if not conffile.exists():
 		import casimport
 		with importlib.resources.path(casimport,
 		    'default.conf') as defconf:
 			shutil.copy(defconf, conffile)
 
+	cp = configparser.ConfigParser()
+	cp.read(conffile)
+
+	modorder = [ x.strip() for x in
+	    cp['casimport']['module_prio'].split(',') ]
+
+	for i in modorder:
+		modfun = _supportedmodules[cp[i]['type']]
+		casf.register(modfun(cp[i]))
+
 	cachedir = basedir / 'cache'
 	cachedir.mkdir(parents=True, exist_ok=True)
 
@@ -484,6 +521,21 @@ class Test(unittest.TestCase):
 		# and when disconnected as second time, nothing happens
 		f.disconnect()
 
+	def test_conforder(self):
+		conf = self.fixtures / 'ordertest.conf'
+
+		# that w/ a custom config
+		with tempset(os.environ, 'CASIMPORT_CONF', str(conf)), \
+		    CASFinder() as f:
+			# that is gets loaded
+			defaultinit(f)
+
+			# and that the first loader is the HTTPSCAS
+			self.assertIsInstance(f._loaders[0], HTTPSCAS)
+
+			# and that the second loader is the IPFSCAS
+			self.assertIsInstance(f._loaders[1], IPFSCAS)
+
 	def test_defaultinit(self):
 		temphome = self.tempdir / 'home'
 		temphome.mkdir()

casimport/default.conf

@@ -11,7 +11,7 @@ module_prio = homecache, ipfsgw, https
 # Default cache is in the user's home directory.
 
 type = cache
-dir = ~/.casimport/cache
+path = ~/.casimport/cache
 
 #size = 10MB
 

fixtures/ordertest.conf

@@ -0,0 +1,9 @@
+[casimport]
+module_prio = https, ipfsgw
+
+[ipfsgw]
+type = ipfs
+gateway = https://gateway.ipfs.io/ipfs/
+
+[https]
+type = https