Polymorphic pin()

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index 662b425286b87a8c1ac25ac7ee318e26ca2ee466..a90ec3b594e0e51e997017a4af2467b0df8242c9 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -101,7 +101,9 @@ class AliasSearchPath(SearchPath):
         assert not hasattr(self, 'git_repo')
 
 
-class TarrableSearchPath(SearchPath):
+# (This lint-disable is for pylint bug https://github.com/PyCQA/pylint/issues/179
+# which is fixed in pylint 2.5.)
+class TarrableSearchPath(SearchPath, ABC):  # pylint: disable=abstract-method
     channel_html: bytes
     channel_url: str
     forwarded_url: str
@@ -111,21 +113,6 @@ class TarrableSearchPath(SearchPath):
     old_git_revision: str
     table: Dict[str, ChannelTableEntry]
 
-    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
-        if hasattr(self, 'git_revision'):
-            self.old_git_revision = self.git_revision
-            del self.git_revision
-
-        if 'channel_url' in conf:
-            pin_channel(v, self)
-            conf['release_name'] = self.release_name
-            conf['tarball_url'] = self.table['nixexprs.tar.xz'].absolute_url
-            conf['tarball_sha256'] = self.table['nixexprs.tar.xz'].digest
-        else:
-            git_fetch(v, self)
-            conf['release_name'] = git_revision_name(v, self)
-        conf['git_revision'] = self.git_revision
-
     def fetch(self, v: Verification, section: str,
               conf: configparser.SectionProxy) -> str:
         if 'git_repo' not in conf or 'release_name' not in conf:
@@ -142,6 +129,30 @@ class TarrableSearchPath(SearchPath):
         return git_get_tarball(v, self)
 
 
+class GitSearchPath(TarrableSearchPath):
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
+        if hasattr(self, 'git_revision'):
+            self.old_git_revision = self.git_revision
+            del self.git_revision
+
+        git_fetch(v, self)
+        conf['release_name'] = git_revision_name(v, self)
+        conf['git_revision'] = self.git_revision
+
+
+class ChannelSearchPath(TarrableSearchPath):
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
+        if hasattr(self, 'git_revision'):
+            self.old_git_revision = self.git_revision
+            del self.git_revision
+
+        pin_channel(v, self)
+        conf['release_name'] = self.release_name
+        conf['tarball_url'] = self.table['nixexprs.tar.xz'].absolute_url
+        conf['tarball_sha256'] = self.table['nixexprs.tar.xz'].digest
+        conf['git_revision'] = self.git_revision
+
+
 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
 
     def throw(error: OSError) -> None:
@@ -547,7 +558,9 @@ def git_revision_name(v: Verification, channel: TarrableSearchPath) -> str:
 def read_search_path(conf: configparser.SectionProxy) -> SearchPath:
     if 'alias_of' in conf:
         return AliasSearchPath(**dict(conf.items()))
-    return TarrableSearchPath(**dict(conf.items()))
+    if 'channel_url' in conf:
+        return ChannelSearchPath(**dict(conf.items()))
+    return GitSearchPath(**dict(conf.items()))
 
 
 def read_config(filename: str) -> configparser.ConfigParser: