Re: XForms: input interation

Steve Lamont (spl@pitstop.ucsd.edu)
Thu, 4 Jun 98 06:55:19 PDT

# To subscribers of the xforms list from spl@pitstop.ucsd.edu (Steve Lamont) :

> Another question: I am piping information to and from my fork'd child. I
> am wondering if the use of io_callbacks would make things easier? Right
> now I have a callback for all of my inputfields to fl_get_input and then
> write (fd, input)... would io_callbacks make things somewhat easier?

It depends.

If you need to service the child's output asynchronously, then yes, an
I/O callback would be the right thing to use. If everything is
synchronous, if all you're doing is writing to the child and expecting
no output back, or you're tossing the output on the floor, then an I/O
callback would be useless.

The I/O callback should only be used where the process -- in this case
the parent -- would block for an appreciable amount of time waiting
for a descriptor to become ready. In that instance, you'd want to
return control to the XForms event handler loop so that the form
wouldn't freeze up or delay user interaction.

spl
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