python-semver · tomschr · Oct 16, 2020 · Jul 21, 2020 · Oct 16, 2020 · Oct 16, 2020
diff --git a/semver.py b/semver.py
@@ -637,8 +637,8 @@ def match(self, match_expr):

        return cmp_res in possibilities

-    @staticmethod
-    def parse(version):
+    @classmethod
+    def parse(cls, version):
        """
        Parse version string to a VersionInfo instance.

@@ -651,7 +651,7 @@ def parse(version):
        VersionInfo(major=3, minor=4, patch=5, \
 prerelease='pre.2', build='build.4')
        """
-        match = VersionInfo._REGEX.match(version)
+        match = cls._REGEX.match(version)
        if match is None:
            raise ValueError("%s is not valid SemVer string" % version)

@@ -661,7 +661,7 @@ def parse(version):
        version_parts["minor"] = int(version_parts["minor"])
        version_parts["patch"] = int(version_parts["patch"])

-        return VersionInfo(**version_parts)
+        return cls(**version_parts)

    def replace(self, **parts):
        """

diff --git a/test_semver.py b/test_semver.py
@@ -1128,3 +1128,21 @@ def test_next_version_with_versioninfo(version, part, expected):
 )
 def test_repr(version, expected):
    assert repr(version) == expected
+
+
+def test_subclass_from_versioninfo():
+    class SemVerWithVPrefix(VersionInfo):
+        @classmethod
+        def parse(cls, version):
+            if not version.startswith("v"):
+                raise ValueError(
+                    "{v}: not a valid semantic version tag".format(v=version)
+                )
+            return super(SemVerWithVPrefix, cls).parse(version[1:])
+
+        def __str__(self):
+            # Reconstruct the tag.
+            return "v" + super(SemVerWithVPrefix, self).__str__()
+
+    v = SemVerWithVPrefix.parse("v1.2.3")
+    assert str(v) == "v1.2.3"