[M3devel] join twice?

[Jay K]

 > And calling Thread.Fork several times on a single Thread.Closure is
 > also idempotent?


Waiting for and getting a result is idempotent, nearly always.

Requesting that work be done may or not be idempotent, depending on the instructions.

 "Increase bank balance by $10" vs. "Set bank balance to $10".

 

 - Jay

 
> To: jay.krell at cornell.edu
> Date: Tue, 3 Nov 2009 07:17:11 -0800
> From: mika at async.async.caltech.edu
> CC: m3devel at elegosoft.com
> Subject: Re: [M3devel] join twice?
> 
> Jay K writes:
> >
> > <5788D8FB-8E44-4F62-BF49-9804E173C8A9 at cs.purdue.edu>
> > 
> >
> > <4AEFF851.1E75.00D7.1 at scires.com>
> >MIME-Version: 1.0
> >
> >--_e29f769b-4ae0-4e1d-9ac5-2f25246d5025_
> >Content-Type: text/plain; charset="iso-8859-1"
> >Content-Transfer-Encoding: quoted-printable
> >
> >
> >To me..with a Win32 background..join means "wait for thread to finish".
> >
> >And there is a separate action "get thread result".
> >
> >You could consider these one merged operation "wait for thread to finish an=
> >d get its result".
> >
> >In either case=2C it is reasonable to allow it multiple times.
> >
> >Waiting for a thread to finish that has already finished is just fast.
> >
> >Getting a thread result that you already got is also easy albeit usually un=
> >necessary.
> 
> And calling Thread.Fork several times on a single Thread.Closure is
> also idempotent?
> 
> It may be "reasonable" to allow such things, but they almost always
> signal bugs in the calling code. Changing the specification to make them
> legal is in my opinion losing a valuable opportunity for preventing bugs.
> Note the Modula-3 philosophy, not everything reasonable (for a C
> programmer's definition of "reasonable", at least) is legal.
> 
> Mika
> 
 		 	   		  
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