DNS lookup problems in HTTP

Scott Wallace scott.wallace at squeakland.org
Sun Nov 3 03:45:40 UTC 2002


Slightly further off-topic...

Another very annoying thing about the code Andreas cites in 
PTM>>accept -- which incidentally arrived in update 
4488keepTextPaneStable by Steve Swerling in August 2001 -- is that 
since this change, if there's a syntax error in a method you try to 
submit, often the selection in the text pane ends up getting set 
wrong, and it can be hard to locate the place in the code where the 
error message has gotten deposited.

Which is to say, even if PTM>>accept were rewritten to use the 
recommended #addAlarm:after: rather than the inappropriate 
#addDeferredUIMessage:, it would still cause grief.

Cheers,

   -- Scott

At 2:41 AM +0100 11/3/02, Andreas Raab wrote:
>Lex,
>
>#addDeferredUIMessage: is abused in various places to do a one-time
>alarm (e.g., the equivalent to #addAlarm:after:). Why anyone would need
>this is beyound me but check out PluggableTextMorph>>accept - I bet you
>wouldn't expect to find #addDeferredUIMessage: here, eh?!. I think that
>#addDeferredUIMessage: should simply raise an error if invoked from the
>UI thread to explicitly prevent abuse such as in this example (and
>that's not the only one but this particular place has bitten me big time
>due to its side effects).
>
>Back to your problem: Raise an exception! It's the right thing to do for
>places where the response to some failed action depends on (possibly
>application specific) context. Why should we poke ourselves with a stick
>in the back and push forward (which is what that code is almost
>literally doing) if we can just say "Sorry Dave, I can't do that" and
>handle the problem in a place where we have enough information to react
>intelligently?! Name lookup failure is an error and should be handled as
>such.
>
>Cheers,
>   - Andreas
>
>>  -----Original Message-----
>>  From: squeak-dev-admin at lists.squeakfoundation.org
>>  [mailto:squeak-dev-admin at lists.squeakfoundation.org] On
>>  Behalf Of Lex Spoon
>>  Sent: Sunday, November 03, 2002 12:21 AM
>>  To: squeak-dev at lists.squeakfoundation.org
>>  Subject: Re: DNS lookup problems in HTTP
>>
>>
>>  Lex Spoon <lex at cc.gatech.edu> wrote:
>>  >
>>  > The method retry:asking:ifGiveUp:  has been modified to run from a
>>  > background thread -- but it seems to now *assume* it is
>>  running from a
>>  > background thread!  Instead of "sema wait", it needs to do something
>>  > like "WorldState runWaitingOnSema: sema" or "WorldState
>>  runUntil: [ sema
>>  > isSignaled]".  Are there methods of this kind in WorldState?!
>>  >
>>
>>  Oh, an alternative would be for addDeferredUIMessage: to run its code
>>  immediately if you are, in fact, in the UI thread.  I'm not
>>  sure how to
>>  detect this, though.
>>
>  > -Lex



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