Convert input to upper case on screen as it is typed

[Ben Finney]

Ben Finney <ben+python at benfinney.id.au> writes:

> Ben Finney <ben+python at benfinney.id.au> writes:
>
> > Okay, ‘termios.tcgetattr’ will let me preserve the attributes, and
> > with Dan Sommers's suggestion of which attribute to use, I may have
> > a shot at setting the terminal attributes.
>
> This works!

Except, it doesn't. As designed and documented in the Single Unix
Specification <URL:http://pubs.opengroup.org/onlinepubs/7908799/>,
the behaviour of the OLCUC feature is:

    OLCUC     Map lower case to upper on output. (LEGACY)

    <URL:http://pubs.opengroup.org/onlinepubs/7908799/xbd/termios.html>

That ominous “LEGACY” annotation is applied, notably, to all the
case-conversion features of ‘termios’.

The mapping is ignorant of Unicode, ignorant of ANSI escape sequences;
it blindly converts bytes via a mapping that assumes all bytes are ASCII
text, regardless of whether those bytes actually represent text.

It breaks the “visual bell” feature, among others. I end up with garbage
on the screen, that would otherwise have been Unicode text or useful
control sequences.

> I had been hoping that I could simply wrap some stream in a simple
> “convert what they actually type so it's upper case” text codec,
> without fiddling at such a low operating-system specific level. This
> is rather more esoteric than I had hoped.

And, it turns out, doesn't address the requirements without causing more
problems.

I am still looking for a solution (a Python-specific one would be fine).

-- 
 \           “Anything that we scientists can do to weaken the hold of |
  `\        religion should be done and may in the end be our greatest |
_o__)                  contribution to civilization.” —Steven Weinberg |
Ben Finney