feat: handle stderr in TTkLog (#448)

libs/pyTermTk/TermTk/TTkCore/log.py

@@ -20,13 +20,15 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-__all__ = ['TTkLog']
+__all__ = ['TTkLog', 'ttk_capture_stderr']
 
 # This code is inspired by
 # https://github.com/ceccopierangiolieugenio/pyCuT/blob/master/cupy/CuTCore/CuDebug.py
 
+import sys
 import inspect
 import logging
+import contextlib
 from collections.abc import Callable, Set
 
 class _TTkContext:
@@ -111,3 +113,28 @@ class TTkLog:
     @staticmethod
     def installMessageHandler(mh: Callable):
         TTkLog._messageHandler.append(mh)
+
+class TTkStderrHandler:
+    def write(self, text):
+        TTkLog.error(text)
+        return len(text)
+
+    def flush(self):
+        pass
+
+    def getvalue(self):
+        raise NotImplementedError()
+
+
+@contextlib.contextmanager
+def ttk_capture_stderr():
+    _stderr_bk = sys.stderr
+    try:
+        sys.stderr = TTkStderrHandler()
+        yield
+    except Exception as e:
+        sys.stderr = _stderr_bk
+        TTkLog.critical(f"Caught an exception: {e}")
+        print(f"Caught an exception: {e}",sys.stderr)
+    finally:
+        sys.stderr = _stderr_bk

libs/pyTermTk/TermTk/TTkCore/ttk.py

@@ -25,7 +25,6 @@ __all__ = ['TTk']
 import os
 import signal
 import time
-import queue
 import threading
 import platform
 
@@ -36,7 +35,7 @@ from TermTk.TTkCore.TTkTerm.inputmouse import TTkMouseEvent
 from TermTk.TTkCore.TTkTerm.term import TTkTerm
 from TermTk.TTkCore.signal import pyTTkSignal, pyTTkSlot
 from TermTk.TTkCore.constant import TTkK
-from TermTk.TTkCore.log import TTkLog
+from TermTk.TTkCore.log import TTkLog, ttk_capture_stderr
 from TermTk.TTkCore.cfg import TTkCfg, TTkGlbl
 from TermTk.TTkCore.helper import TTkHelper
 from TermTk.TTkCore.timer import TTkTimer
@@ -75,8 +74,6 @@ class _MouseCursor():
             self.updated.emit()
 
 class TTk(TTkContainer):
-
-
     __slots__ = (
         '_termMouse', '_termDirectMouse',
         '_title',
@@ -143,6 +140,10 @@ class TTk(TTkContainer):
             self.time  = curtime
 
     def mainloop(self):
+        with ttk_capture_stderr():
+            self._mainloop_1()
+
+    def _mainloop_1(self):
         try:
             '''Enters the main event loop and waits until :meth:`~quit` is called or the main widget is destroyed.'''
             TTkLog.debug( "" )
@@ -185,7 +186,7 @@ class TTk(TTkContainer):
                 self._mouseCursor.updated.connect(self.update)
                 self.paintChildCanvas = self._mouseCursorPaintChildCanvas
 
-            self._mainLoop()
+            self._mainLoop_2()
         finally:
             if platform.system() != 'Emscripten':
                 TTkHelper.quitEvent.emit()
@@ -205,7 +206,7 @@ class TTk(TTkContainer):
         color = self._mouseCursor._color
         self.getCanvas().drawChar(char=ch, pos=pos, color=color)
 
-    def _mainLoop(self):
+    def _mainLoop_2(self):
         if platform.system() == 'Emscripten':
             return
         TTkInput.start()

tests/pytest/test_005_stderr.py

@@ -0,0 +1,71 @@
+# MIT License
+#
+# Copyright (c) 2025 Eugenio Parodi <ceccopierangiolieugenio AT googlemail DOT com>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import sys, os, io
+import logging
+import pytest
+from typing import Union, Optional
+
+sys.path.append(os.path.join(sys.path[0],'../../libs/pyTermTk'))
+
+import TermTk as ttk
+
+
+class FakeStderr():
+    value = []
+
+def message_handler(mode, context, message):
+    FakeStderr.value.append(message)
+    msgType = "NONE"
+    if   mode == ttk.TTkLog.InfoMsg:     msgType = "[INFO]"
+    elif mode == ttk.TTkLog.WarningMsg:  msgType = "[WARNING]"
+    elif mode == ttk.TTkLog.CriticalMsg: msgType = "[CRITICAL]"
+    elif mode == ttk.TTkLog.FatalMsg:    msgType = "[FATAL]"
+    elif mode == ttk.TTkLog.ErrorMsg:    msgType = "[ERROR]"
+    print(f"{msgType} {context.file} {message}")
+
+def test_stderr_01():
+    ttk.TTkLog.installMessageHandler(message_handler)
+
+    print('Test',file=sys.stderr)
+    with ttk.ttk_capture_stderr():
+        print('XXXXX Test',file=sys.stderr)
+        with open('pippo','r') as f:
+            f.read()
+        raise ValueError('YYYYY Test')
+    print('After Test')
+
+def test_ttk_capture_stderr():
+    ttk.TTkLog.installMessageHandler(message_handler)
+    with ttk.ttk_capture_stderr() as fake_stderr:
+        print("This is an error message", file=sys.stderr)
+    output = FakeStderr.value
+    assert "This is an error message" in output
+
+def test_ttk_capture_stderr_exception_handling():
+    ttk.TTkLog.installMessageHandler(message_handler)
+    with ttk.ttk_capture_stderr() as fake_stderr:
+        raise ValueError("Test exception")
+    # After the exception, sys.stderr should be restored
+    output = FakeStderr.value
+    assert any("Test exception" in _o for _o in output)
+    assert isinstance(sys.stderr, io.TextIOWrapper) or sys.stderr is sys.__stderr__

tools/check.import.sh

@@ -15,9 +15,11 @@ __check(){
             -e "signal.py:import asyncio" \
             -e "signal.py:import importlib.util" \
             -e "colors.py:from .colors_ansi_map" \
-            -e "log.py:import inspect" \
-            -e "log.py:import logging" \
-            -e "log.py:from collections.abc import Callable, Set" \
+            -e "TTkCore/log.py:import inspect" \
+            -e "TTkCore/log.py:import logging" \
+            -e "TTkCore/log.py:import sys" \
+            -e "TTkCore/log.py:import contextlib" \
+            -e "TTkCore/log.py:from collections.abc import Callable, Set" \
             -e "term.py:import importlib.util" \
             -e "term.*.py:import sys, os, signal" \
             -e "term.*.py:from .term_base import TTkTermBase" \