From: Robert Klemme <shortcutter@...>
Date: 2010-09-30T22:16:09+09:00
Subject: Re: Calling a method in the context of a specific thread

On Thu, Sep 30, 2010 at 2:26 PM, Ralph Shnelvar <ralphs@dos32.com> wrote:
> Robert,
>
> Thursday, September 30, 2010, 12:10:34 AM, you wrote:
>
> RK> On 09/29/2010 03:22 AM, Ralph Shnelvar wrote:
>>> [Note:  parts of this message were removed to make it a legal post.]
>
>>> Background:
>
>>> I am writing an FXRuby program.  My question should be independent of FXRuby, though.
>
>>> FXRuby is a GUI for Ruby.
>
>>> If I understand some of the comments made here (and I probably don't) [see subject: interpreter cannot enter in the context from another thread] it is a bad thing to attempt to run an FXRuby function in a non-main thread.
>
>
>
>
>>> So ... I have a non-main thread that wants to display a message box (i.e. "call" FXMessageBox").
>
>>> How can I invoke FXMessageBox in the context of the main thread?
>
>
>
>>> I can think of all sorts of ugly solutions.
>
>>> For instance:
>
>>> 1) Set some global_variable indicating the task I want to perform in the main thread.
>>> 2) Do a thread.stop
>>> 3) have a timer in the main thread and have it dispatch based on global_variable
>>> 4) save the return code of FXMessageBox in a thread local variable the not-main-thread
>>> 5) Do a thread.run to wake up the stopped not-main-thread.
>
> RK> 6) Have a task queue which is read in the main thread.  You can even
> RK> store lambdas in there.
>
> Please explain more; a lot more.
>
> I am particularly confused how a task queue would work given that nothing in the main thread can block since that would stop FXRuby's message pump.

Actually I do not know RXRuby - I just answered based on the
information in your posting.  Maybe there is a queue in FXRuby that is
regularly read from the main thread and which you can use.  Actually
you need to be able to interfere with FXRuby's processing otherwise I
don't understand how you want to make option 1 work.

Btw, a quick Google revealed this at the top of the list:

http://www.fxruby.org/doc/differences.html#d0e5063

Kind regards

robert

-- 
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