Re: Polling stdin...

[Mark Edgar <medgar@...>]

Matthew Percival wrote:
> G'Day,
>
> 	I have been searching around on this topic, and have not come up with
> anything substantial, so I suspect there is currently no option for
> this, but I thought it best to ask, in case a skilled Lua programmer
> knows a way.  Quite simply, I want to check stdin to see if there is
> anything currently buffered, and only perform stdin:read() if there is.
> As a simple example:
>
> i = 1
> while (i != 0) do
> 	if (stdin:read("*ready")) then -- somehow test if it's ready
> 		i = stdin:read("*all")
> 	else
> 		print "Looping again...\n"
> end
>
> 	So, if the user ever types a 0, the loop will exit; if the user types
> nothing, it will continually print on the screen.  Perhaps a bad
> example, but a nice, simple one.  Can this be done, or would something
> like this have to be written in first?

I believe that this applies:

http://www.c-faq.com/osdep/readavail.html

In other words, there is no way to do this in standard C, as C does not 
provide non-blocking I/O.

That being said, it is possible to write a C module for "console" I/O 
which would provide this behavior on <insert-your-platform-of-choice>.

I don't know of any projects which do this.

					-Mark