NullWriter has no attribute 'closed'

[kristjanvalur]

This is similar to issue #1883
It is triggered when using the "click" library in a PyInstaller --noconsole application.

A workaround is as follows:

# fixup somw problems from pyinstaller
if "NullWriter" in str(type(sys.stdout)):
    sys.stdout.closed = sys.stderr.closed = False

I suggest adding a class attribute, closed=False to fix this.
You may want to add the "errors" and "newlines" attributes as well, see the python docs.

[bersbersbers]

Came across basically the same issue with reconfigure:

AttributeError: 'NullWriter' object has no attribute 'reconfigure'

Honestly, I find the practice of overwriting sys.stdout/sys.stderr in

pyinstaller/PyInstaller/loader/pyiboot01_bootstrap.py

Lines 80 to 84 in 7b2b93a

	# sys.stdout/err is None in GUI mode on Windows.
	if sys.stdout is None:
	sys.stdout = NullWriter()
	if sys.stderr is None:
	sys.stderr = NullWriter()

quite questionable. The Python docs say that the two are "file objects" and "regular text files" (source), the APIs of which are defined in the io module (source). Replacing these objects with a class not derived from TextIOWrapper, TextIOBase or at least IOBase is a recipe for incompatibilities such as #1883 or the ones reported here.

Regarding the above workaround, I'd probably prefer a more focused approach using

if not hasattr(sys.stdout, "closed"):
    ...

[rokm]

Honestly, I find the practice of overwriting sys.stdout/sys.stderr in

pyinstaller/PyInstaller/loader/pyiboot01_bootstrap.py

Lines 80 to 84 in 7b2b93a

	# sys.stdout/err is None in GUI mode on Windows.
	if sys.stdout is None:
	sys.stdout = NullWriter()
	if sys.stderr is None:
	sys.stderr = NullWriter()

quite questionable.

I second that sentiment. Judging by the surrounding comments, this was added as a work-around for an issue from 15 years ago (http://bugs.python.org/issue1415), which has been addressed in python 3.0. So I think it is time to get rid of the NullWriter. I'm quite sure this will trip some user code that fails to check if sys.stderr/sys.stdout are None before accessing it, but that's the behavior they would get in pythonw.exe, as well, and should handle it themselves however they see it fit (e.g., by installing their own equivalent file-like object).