Move find_codec_by_name function into the codecs package module

Author: ntninja

multiaddr/codec.py

@@ -1,33 +1,15 @@
 # -*- encoding: utf-8 -*-
-from __future__ import absolute_import
-import importlib
-
 import six
 import varint
 
+from .codecs import LENGTH_PREFIXED_VAR_SIZE
+from .codecs import codec_by_name
+
 from .protocols import protocol_with_code
 from .protocols import protocol_with_name
 from .protocols import read_varint_code
 
 
-# These are special sizes
-LENGTH_PREFIXED_VAR_SIZE = -1
-
-
-class NoneCodec:
-	SIZE = 0
-	IS_PATH = False
-
-
-CODEC_CACHE = {}
-def find_codec_by_name(name):
-    if name is None:  # Special “do nothing – expect nothing” pseudo-codec
-        return NoneCodec
-    codec = CODEC_CACHE.get(name)
-    if not codec:
-        codec = CODEC_CACHE[name] = importlib.import_module(".codecs.{0}".format(name), __package__)
-    return codec
-
 
 def string_to_bytes(string):
     if not string:
@@ -77,7 +59,7 @@ def string_iter(string):
 		element = sp.pop(0)
 		proto = protocol_with_name(element)
 		try:
-			codec = find_codec_by_name(proto.codec)
+			codec = codec_by_name(proto.codec)
 		except ImportError as exc:
 			six.raise_from(ValueError("failed to parse %s addr: unknown" % proto.name), exc)
 		value = None
@@ -101,7 +83,7 @@ def bytes_iter(buf):
 		code, num_bytes_read = read_varint_code(buf)
 		proto = protocol_with_code(code)
 		try:
-			codec = find_codec_by_name(proto.codec)
+			codec = codec_by_name(proto.codec)
 		except ImportError as exc:
 			six.raise_from(ValueError("failed to parse %s addr: unknown" % proto.name), exc)
 		size, num_bytes_read2 = size_for_addr(codec, buf[num_bytes_read:])

multiaddr/codecs/__init__.py

@@ -0,0 +1,22 @@
+# -*- encoding: utf-8 -*-
+from __future__ import absolute_import
+import importlib
+
+
+# These are special sizes
+LENGTH_PREFIXED_VAR_SIZE = -1
+
+
+class NoneCodec:
+	SIZE = 0
+	IS_PATH = False
+
+
+CODEC_CACHE = {}
+def codec_by_name(name):
+    if name is None:  # Special “do nothing – expect nothing” pseudo-codec
+        return NoneCodec
+    codec = CODEC_CACHE.get(name)
+    if not codec:
+        codec = CODEC_CACHE[name] = importlib.import_module(".{0}".format(name), __name__)
+    return codec

multiaddr/codecs/fspath.py

@@ -3,7 +3,7 @@
 
 import six
 
-from ..codec import LENGTH_PREFIXED_VAR_SIZE
+from . import LENGTH_PREFIXED_VAR_SIZE
 
 
 SIZE = LENGTH_PREFIXED_VAR_SIZE

multiaddr/codecs/idna.py

@@ -2,7 +2,7 @@
 
 import idna
 
-from ..codec import LENGTH_PREFIXED_VAR_SIZE
+from . import LENGTH_PREFIXED_VAR_SIZE
 
 
 SIZE = LENGTH_PREFIXED_VAR_SIZE

multiaddr/codecs/p2p.py

@@ -3,7 +3,7 @@
 import base58
 import six
 
-from ..codec import LENGTH_PREFIXED_VAR_SIZE
+from . import LENGTH_PREFIXED_VAR_SIZE
 
 
 SIZE = LENGTH_PREFIXED_VAR_SIZE

multiaddr/protocols.py

@@ -3,6 +3,9 @@
 import six
 import varint
 
+from .codecs import codec_by_name
+
+
 # source of protocols https://github.com/multiformats/multicodec/blob/master/table.csv#L382
 # replicating table here to:
 # 1. avoid parsing the csv
@@ -63,7 +66,6 @@
 ]
 
 
-find_codec_by_name = None
 
 class Protocol(object):
     __slots__ = [
@@ -89,19 +91,11 @@ def __init__(self, code, name, codec):
 
     @property
     def size(self):
-        global find_codec_by_name
-        if find_codec_by_name is None:
-            from .codec import find_codec_by_name
-
-        return find_codec_by_name(self.codec).SIZE
+        return codec_by_name(self.codec).SIZE
 
     @property
     def path(self):
-        global find_codec_by_name
-        if find_codec_by_name is None:
-            from .codec import find_codec_by_name
-
-        return find_codec_by_name(self.codec).IS_PATH
+        return codec_by_name(self.codec).IS_PATH
 
     @property
     def vcode(self):

tests/test_codec.py

@@ -1,7 +1,8 @@
 # -*- encoding: utf-8 -*-
 import pytest
 
-from multiaddr.codec import find_codec_by_name
+from multiaddr.codecs import codec_by_name
+
 from multiaddr.codec import bytes_iter
 from multiaddr.codec import bytes_to_string
 from multiaddr.codec import size_for_addr
@@ -53,7 +54,7 @@
     ('p2p', b'\x40\x50\x60\x51', (64, 1)),
 ])
 def test_size_for_addr(codec_name, buf, expected):
-    assert size_for_addr(find_codec_by_name(codec_name), buf) == expected
+    assert size_for_addr(codec_by_name(codec_name), buf) == expected
 
 
 @pytest.mark.parametrize("buf, expected", [
@@ -70,13 +71,13 @@ def test_bytes_iter(buf, expected):
 
 @pytest.mark.parametrize("proto, buf, expected", ADDR_BYTES_MAP_STR_TEST_DATA)
 def test_codec_to_string(proto, buf, expected):
-    assert find_codec_by_name(proto.codec).to_string(proto, buf) == expected
+    assert codec_by_name(proto.codec).to_string(proto, buf) == expected
 
 
 @pytest.mark.parametrize("proto, expected, string",
                          ADDR_BYTES_MAP_STR_TEST_DATA)
 def test_codec_to_bytes(proto, string, expected):
-    assert find_codec_by_name(proto.codec).to_bytes(proto, string) == expected
+    assert codec_by_name(proto.codec).to_bytes(proto, string) == expected
 
 
 @pytest.mark.parametrize("string, buf", BYTES_MAP_STR_TEST_DATA)
@@ -143,12 +144,12 @@ def test_bytes_to_string_value_error(protocol_extension, bytes):
 ])
 def test_codec_to_bytes_value_error(proto, address):
     with pytest.raises(ValueError):
-        find_codec_by_name(proto.codec).to_bytes(proto, address)
+        codec_by_name(proto.codec).to_bytes(proto, address)
 
 
 @pytest.mark.parametrize("proto, buf", [
     (_names_to_protocols['tcp'], b'\xff\xff\xff\xff')
 ])
 def test_codec_to_string_value_error(proto, buf):
     with pytest.raises(ValueError):
-        find_codec_by_name(proto.codec).to_string(proto, buf)
+        codec_by_name(proto.codec).to_string(proto, buf)