Re: $ shorthand side-effect (was Digest for EUforum at topica.com, issue 6333)
CChris wrote:
>
> Chris Bensler wrote:
> >
> > It's more prevalent because of how you changed the order of evaluation.
> > IMO, the previous behaviour was more logical. That is all. It now requires
> > more
> > thought to determine if there will be side-effects.
> >
>
> I wouldn't say it was logical really. Please read
> <a
> href="http://www.listfilter.com/cgi-bin/esearch.exu?thread=1&fromMonth=B&fromYear=7&toMonth=1&toYear=8&keywords=">http://www.listfilter.com/cgi-bin/esearch.exu?thread=1&fromMonth=B&fromYear=7&toMonth=1&toYear=8&keywords=</a>"Bug+or+inconsistency+in+evaluation+rules+regarding+edge+effects"
>
> I didn't test that code under 3.0, but can't see why it's strange behaviour
>
> could have been modified.
*more* logical. It's still an undefined behaviour.
Here is a sample of code that I think demonstrates why the code you posted in
the link works the way it does.
l=2
?(l+0+f(3)+f(1)+2*l)
--result: 8=2+0+2+2+2*1
The reason that the other statements are unexepected results is because in the
first part of the expression, l+f() share the same operator.
l is read first but it's modified in f() before the term is actually evaluated.
By adding the 0 operand, I decoupled l+f(), so l is properly evaluated first
before f() is ever encountered.
(The behaviour is the same using 3.0)
The difference from 2.4 and 2.5 is how subscripting is evaluated.
Chris Bensler
~ The difference between ordinary and extraordinary is that little extra ~
http://empire.iwireweb.com - Empire for Euphoria
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