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I'm a perl Tk newbie trying to create a pgm to display the status of
several servers by a green/red indicator light. After going over some
howto's & examples, I'm still stumped.

All of the examples I can find are geared towards dealing with some user
interaction (clicking buttons, typing text, etc.), but I'm looking for a
non-interactive update of status lights, say when a server goes down,
stops listening on a port, etc.

Basically I'd like to know how to update a widget color based on results
from a monitoring subroutine - ie how to pass info back into the Tk
window. I tried setting a text widget to a global variable that gets
manipulated in a routine forked prior to MainLoop, but no luck.

Sooooo....can anybody provide guidance as how to pass values back into a
Tk window? Examples greatly appreciated..

TIA

Chris <> writes:

> I'm a perl Tk newbie trying to create a pgm to display the status of
> several servers by a green/red indicator light. After going over some
> howto's & examples, I'm still stumped.
>
> All of the examples I can find are geared towards dealing with some
> user interaction (clicking buttons, typing text, etc.), but I'm
> looking for a non-interactive update of status lights, say when a
> server goes down, stops listening on a port, etc.
>
> Basically I'd like to know how to update a widget color based on
> results from a monitoring subroutine - ie how to pass info back into
> the Tk window. I tried setting a text widget to a global variable that
> gets manipulated in a routine forked prior to MainLoop, but no luck.

Tk is event based. That means that you're just executing code whenever
some event happens. The event can be a user action but it can also be
activity on a socket or a timeout or whatever.

You may want to look at the Tk::after manpage.

Joost.

Joost Diepenmaat wrote:
> Chris <> writes:
>
>
>>I'm a perl Tk newbie trying to create a pgm to display the status of
>>several servers by a green/red indicator light. After going over some
>>howto's & examples, I'm still stumped.
>>
>>All of the examples I can find are geared towards dealing with some
>>user interaction (clicking buttons, typing text, etc.), but I'm
>>looking for a non-interactive update of status lights, say when a
>>server goes down, stops listening on a port, etc.
>>
>>Basically I'd like to know how to update a widget color based on
>>results from a monitoring subroutine - ie how to pass info back into
>>the Tk window. I tried setting a text widget to a global variable that
>>gets manipulated in a routine forked prior to MainLoop, but no luck.
>
>
> Tk is event based. That means that you're just executing code whenever
> some event happens. The event can be a user action but it can also be
> activity on a socket or a timeout or whatever.
>
> You may want to look at the Tk::after manpage.
>
> Joost.
>
>
Thx...I'll check that out

On Tue, 05 Feb 2008 11:43:55 -0600, Chris wrote:

> I'm a perl Tk newbie trying to create a pgm to display the status of
> several servers by a green/red indicator light. After going over some
> howto's & examples, I'm still stumped.
>
> All of the examples I can find are geared towards dealing with some user
> interaction (clicking buttons, typing text, etc.), but I'm looking for a
> non-interactive update of status lights, say when a server goes down,
> stops listening on a port, etc.
>
> Basically I'd like to know how to update a widget color based on results
> from a monitoring subroutine - ie how to pass info back into the Tk
> window. I tried setting a text widget to a global variable that gets
> manipulated in a routine forked prior to MainLoop, but no luck.
>
> Sooooo....can anybody provide guidance as how to pass values back into a
> Tk window? Examples greatly appreciated..
>
> TIA

It may be easier to destroy and recreate a widget, eg. in a different
color, than to change the color of an existing widget, and it looks
exactly the same.