On 10/6/2017 1:32 PM, Chris Angelico wrote:
On Sat, Oct 7, 2017 at 4:05 AM, Grant Edwards <grant.b.edwa...@gmail.com> wrote:
On 2017-10-06, Thomas Jollans <t...@tjol.eu> wrote:
Seriously? sys.stdin can be None? That's terrifying.
Why?
Unix daemons usually run with no stdin, stderr, or stdout.
And yes, people do write Unix daemons in Python.
Hmm, but usually I would expect them still to HAVE those streams,
they're just connected to /dev/null or something. I don't think they
would actually fail to exist, would they?
On Windows, a file run with pythonw.exe (no console) starts with
sys.[__]std[in|out|err][__] (6 entries) set to None. The program can
reset them as it pleases. In an IDLE user process, the non-dunder names
are set to objects that communicate with the IDLE GUI process.
>>> import sys; sys.__stdin__, sys.stdin
(None, <idlelib.run.PseudoInputFile object at 0x0000014639AA7E10>)
GUI programs interact with the OS and thence users through event streams
rather than character streams. (Note that terminal escape sequences are
character-encoded events.) That is why automating a GUI usually
requires a special program than can generate and inject events into the
event queue read by the GUI program.
--
Terry Jan Reedy
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