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Improve stdin, stdout, and stderr redirection in PythonQt #286

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Merged
merged 3 commits into from
Sep 1, 2025
Merged

Improve stdin, stdout, and stderr redirection in PythonQt #286

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3eed19c
Fix setRedirectStdInCallbackEnabled
jcfr Apr 23, 2019
f630bc9
Add support for enabling stdout/stderr redirection
jcfr Apr 23, 2019
46a00b8
Fix windows build error renaming stdout ivar
jcfr Apr 24, 2019
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68 changes: 54 additions & 14 deletions src/PythonQt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -502,11 +502,11 @@ void PythonQt::setRedirectStdInCallbackEnabled(bool enabled)
sys.setNewRef(PyImport_ImportModule("sys"));

if (enabled) {
if( !PyObject_HasAttrString(sys.object(), "pythonqt_stdin") ) {
if( PyObject_HasAttrString(sys.object(), "pythonqt_stdin") ) {
PyObject_SetAttrString(sys.object(), "stdin", PyObject_GetAttrString(sys.object(), "pythonqt_stdin"));
}
} else {
if( !PyObject_HasAttrString(sys.object(), "pythonqt_original_stdin") ) {
if( PyObject_HasAttrString(sys.object(), "pythonqt_original_stdin") ) {
PyObject_SetAttrString(sys.object(), "stdin", PyObject_GetAttrString(sys.object(), "pythonqt_original_stdin"));
}
}
Expand Down Expand Up @@ -1864,18 +1864,22 @@ void PythonQt::initPythonQtModule(bool redirectStdOut, const QByteArray& pythonQ
PythonQtObjectPtr sys;
sys.setNewRef(PyImport_ImportModule("sys"));

if (redirectStdOut) {
PythonQtObjectPtr out;
PythonQtObjectPtr err;
// create a redirection object for stdout and stderr
out = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
((PythonQtStdOutRedirect*)out.object())->_cb = stdOutRedirectCB;
err = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,nullptr, nullptr);
((PythonQtStdOutRedirect*)err.object())->_cb = stdErrRedirectCB;
// replace the built in file objects with our own objects
PyModule_AddObject(sys, "stdout", out);
PyModule_AddObject(sys, "stderr", err);
}
// Backup original 'sys.stdout' and 'sys.stderr'
PyModule_AddObject(sys, "pythonqt_original_stdout", PyObject_GetAttrString(sys, "stdout"));
PyModule_AddObject(sys, "pythonqt_original_stderr", PyObject_GetAttrString(sys, "stderr"));

// Create a redirection object for stdout and stderr
PythonQtObjectPtr out;
PythonQtObjectPtr err;
out = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,NULL, NULL);
((PythonQtStdOutRedirect*)out.object())->_cb = stdOutRedirectCB;
err = PythonQtStdOutRedirectType.tp_new(&PythonQtStdOutRedirectType,NULL, NULL);
((PythonQtStdOutRedirect*)err.object())->_cb = stdErrRedirectCB;
// replace the built in file objects with our own objects
PyModule_AddObject(sys, "pythonqt_stdout", out);
PyModule_AddObject(sys, "pythonqt_stderr", err);

setRedirectStdOutCallbackEnabled(redirectStdOut);

// add PythonQt to the list of builtin module names
PyObject *old_module_names = PyObject_GetAttrString(sys.object(),"builtin_module_names");
Expand All @@ -1901,6 +1905,42 @@ void PythonQt::initPythonQtModule(bool redirectStdOut, const QByteArray& pythonQ
#endif
}

bool PythonQt::redirectStdOutCallbackEnabled() const
{
PythonQtObjectPtr sys;
sys.setNewRef(PyImport_ImportModule("sys"));

PythonQtObjectPtr pythonqt_stdout;
pythonqt_stdout.setNewRef(PyObject_GetAttrString(sys.object(), "pythonqt_stdout"));

PythonQtObjectPtr sys_stdout;
sys_stdout.setNewRef(PyObject_GetAttrString(sys.object(), "stdout"));

return PyObject_RichCompareBool(pythonqt_stdout.object(), sys_stdout.object(), Py_EQ);
}

void PythonQt::setRedirectStdOutCallbackEnabled(bool enabled)
{
PythonQtObjectPtr sys;
sys.setNewRef(PyImport_ImportModule("sys"));

if (enabled) {
if( PyObject_HasAttrString(sys.object(), "pythonqt_stdout") ) {
PyModule_AddObject(sys.object(), "stdout", PyObject_GetAttrString(sys.object(), "pythonqt_stdout"));
}
if( PyObject_HasAttrString(sys.object(), "pythonqt_stderr") ) {
PyModule_AddObject(sys.object(), "stderr", PyObject_GetAttrString(sys.object(), "pythonqt_stderr"));
}
} else {
if( PyObject_HasAttrString(sys.object(), "pythonqt_original_stdout") ) {
PyModule_AddObject(sys.object(), "stdout", PyObject_GetAttrString(sys.object(), "pythonqt_original_stdout"));
}
if( PyObject_HasAttrString(sys.object(), "pythonqt_original_stderr") ) {
PyModule_AddObject(sys.object(), "stderr", PyObject_GetAttrString(sys.object(), "pythonqt_original_stderr"));
}
}
}

QString PythonQt::getReturnTypeOfWrappedMethod(PyObject* module, const QString& name)
{
QStringList tmp = name.split(".");
Expand Down
12 changes: 12 additions & 0 deletions src/PythonQt.h
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Original file line number Diff line number Diff line change
Expand Up @@ -268,6 +268,18 @@ class PYTHONQT_EXPORT PythonQt : public QObject {

//@}

//---------------------------------------------------------------------------
//! \name Standard output handling
//@{

//! return \a true if std out/err redirection is enabled.
bool redirectStdOutCallbackEnabled() const;

//! enable or disable std out/err redirection to pythonStdOut() and pythonStdErr() signals.
void setRedirectStdOutCallbackEnabled(bool enabled);

//@}

//---------------------------------------------------------------------------
//! \name Modules
//@{
Expand Down
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