Re: Redirection of standard streams

On Mon, May 12, 2014 at 6:35 PM, Per Hedbor () @ Pike (-) importmöte
för mailinglistan <[email protected]> wrote:
> First: assign() only modifies what the pike object sees as it's
> internal fd.
>
> write() and werror() are however resolved when the master is compiled
> to point to specific low-level fd (or, rather, they have their own
> Stdio.File instances, and as such are not affected by what happens
> with Stdio.std*) (well, you could always use add_constant to change
> them for newly compiled code, but it will not change what they point
> to for old code).

Technically I'm not actually trying to redirect werror, but a warning
message from GTK2.PangoTabArray(0,0) - it's printed to stderr,
regardless of the Pike functions. So for this to work, I have to
mutate FD 2 itself. In Pike 8.0, this works fine; I created a class
that wraps up the details, and I simply allocate an instance of it,
and when that instance disappears, the redirection is undone. In 7.8,
I've managed to get the redirection itself working, just not the
unredirection.

> It is possible to do an actual dup() in pike 7.8 by digging around in
> the internals of Stdio.File:
>
>     Stdio.File new_stdout;
>
>     #if __VERISON__ < 8.0
>       new_stdout = Stdio.File();
>       new_stdout->assign( Stdio.stdin->_fd->dup() );
>     #else
>       new_stdout = Stdio.stdout.dup();
>     #endif
>
> 8.0 will hopefully soon be the new stable release (and decade now..)
> so backporting should not be needed.

Eww, I don't like digging in internals like that! But it does seem to
work; thanks! I'll deploy that.

Of course, ideal would be for there to be a way for GTK2.PangoTabArray
objects to be constructed without generating warnings. But in the
absence of that, I can at least construct the eight I need without
spamming the user with scary text.

Thanks for the help!

ChrisA