PrefsFile: Deserialize GenericAlias properly (jorio#112)

Author: jorio

gitfourchette/prefsfile.py

@@ -1,5 +1,5 @@
 # -----------------------------------------------------------------------------
-# Copyright (C) 2025 Iliyas Jorio.
+# Copyright (C) 2026 Iliyas Jorio.
 # This file is part of GitFourchette, distributed under the GNU GPL v3.
 # For full terms, see the included LICENSE file.
 # -----------------------------------------------------------------------------
@@ -10,7 +10,7 @@
 import logging
 import os
 import typing
-from types import NoneType, UnionType
+from types import NoneType, UnionType, GenericAlias
 from typing import Any
 
 from gitfourchette import pycompat  # noqa: F401 - StrEnum for Python 3.10
@@ -182,7 +182,7 @@ def encode(o: Any) -> Any:
         return o
 
     @staticmethod
-    def decode(o: Any, dstType: type | UnionType) -> Any:
+    def decode(o: Any, dstType: type | UnionType | GenericAlias) -> Any:
         """ Convert a value coming from a JSON blob to a target type """
         construct: typing.Callable[[Any], Any] | None = None
 
@@ -192,6 +192,10 @@ def decode(o: Any, dstType: type | UnionType) -> Any:
             assert len(union) == 2
             dstType = next(t for t in union if t is not NoneType)
 
+        # Extract generic class from GenericAlias, e.g. list[str] --> list
+        if type(dstType) is GenericAlias:
+            dstType = typing.get_origin(dstType)
+
         srcType: type
         if dstType is bytes:
             srcType = str

gitfourchette/settings.py

@@ -8,7 +8,9 @@
 import enum
 import logging
 import os
+from collections.abc import Iterator
 from contextlib import suppress
+from typing import TypedDict
 
 from gitfourchette import colors
 from gitfourchette import pycompat  # noqa: F401 - StrEnum for Python 3.10
@@ -239,9 +241,15 @@ def isGitSandboxed(self):
 class History(PrefsFile):
     _filename = "history.json"
 
-    repos: dict = dataclasses.field(default_factory=dict)
-    cloneHistory: list = dataclasses.field(default_factory=list)
-    fileDialogPaths: dict = dataclasses.field(default_factory=dict)
+    class JsonRepo(TypedDict, total=False):
+        seq: int
+        length: int
+        nickname: str
+        superproject: str
+
+    repos: dict[str, JsonRepo] = dataclasses.field(default_factory=dict)
+    cloneHistory: list[str] = dataclasses.field(default_factory=list)
+    fileDialogPaths: dict[str, str] = dataclasses.field(default_factory=dict)
     startups: int = 0
 
     _maxSeq = -1
@@ -252,12 +260,12 @@ def addRepo(self, path: str):
         repo['seq'] = self.drawSequenceNumber()
         return repo
 
-    def getRepo(self, path: str) -> dict:
+    def getRepo(self, path: str) -> JsonRepo:
         path = os.path.normpath(path)
         try:
             repo = self.repos[path]
         except KeyError:
-            repo = {}
+            repo: History.JsonRepo = {}
             self.repos[path] = repo
         return repo
 
@@ -274,7 +282,7 @@ def setRepoNickname(self, path: str, nickname: str):
         else:
             repo.pop('nickname', None)
 
-    def getRepoNumCommits(self, path: str):
+    def getRepoNumCommits(self, path: str) -> int:
         repo = self.getRepo(path)
         return repo.get('length', 0)
 
@@ -285,7 +293,7 @@ def setRepoNumCommits(self, path: str, commitCount: int):
         else:
             repo.pop('length', None)
 
-    def getRepoSuperproject(self, path: str):
+    def getRepoSuperproject(self, path: str) -> str:
         repo = self.getRepo(path)
         return repo.get('superproject', "")
 
@@ -296,7 +304,7 @@ def setRepoSuperproject(self, path: str, superprojectPath: str):
         else:
             repo.pop('superproject', None)
 
-    def getRepoTabName(self, path: str):
+    def getRepoTabName(self, path: str) -> str:
         name = self.getRepoNickname(path)
 
         seen = {path}
@@ -321,7 +329,7 @@ def clearRepoHistory(self):
         self.repos.clear()
         self.invalidateSequenceNumber()
 
-    def getRecentRepoPaths(self, n: int, newestFirst=True):
+    def getRecentRepoPaths(self, n: int, newestFirst=True) -> Iterator[str]:
         sortedPaths = (path for path, _ in
                        sorted(self.repos.items(), key=lambda i: i[1].get('seq', -1), reverse=newestFirst))
 
@@ -365,10 +373,10 @@ def invalidateSequenceNumber(self):
 class Session(PrefsFile):
     _filename = "session.json"
 
-    tabs                        : list          = dataclasses.field(default_factory=list)
-    activeTabIndex              : int           = -1
-    windowGeometry              : bytes         = b""
-    splitterSizes               : dict          = dataclasses.field(default_factory=dict)
+    tabs                        : list[str]             = dataclasses.field(default_factory=list)
+    activeTabIndex              : int                   = -1
+    windowGeometry              : bytes                 = b""
+    splitterSizes               : dict[str, list[int]]  = dataclasses.field(default_factory=dict)
 
 
 # Initialize default prefs and history.

test/test_gitfourchette.py

@@ -883,3 +883,26 @@ def testDiffHeader(tempDir, mainWindow):
         rw.jump(NavLocator.inUnstaged("hello.txt"), check=True)
         assert rw.diffArea.diffView.isVisible()
         assert findTextInWidget(rw.diffArea.diffHeader, "hello.txt")
+
+
+def testPrefsFileGenericAliases(tempDir, mainWindow):
+    from gitfourchette import settings
+
+    assert settings.prefs.dontShowAgain == []
+    settings.prefs.dontShowAgain.append("NoFastForwardNecessary")
+    settings.prefs.setDirty()
+    settings.prefs.write()
+    settings.prefs.reset()
+    settings.prefs.load()
+    assert settings.prefs.dontShowAgain == ["NoFastForwardNecessary"]
+
+    assert settings.history.cloneHistory == []
+    assert not settings.history.getRepoNickname("/tmp/hello", strict=True)
+    settings.history.cloneHistory.append("https://github.com/jorio/gitfourchette")
+    settings.history.setRepoNickname("/tmp/hello", "HelloWorld")
+    settings.history.setDirty()
+    settings.history.write()
+    settings.history.reset()
+    settings.history.load()
+    assert settings.history.cloneHistory == ["https://github.com/jorio/gitfourchette"]
+    assert settings.history.getRepoNickname("/tmp/hello", strict=True) == "HelloWorld"