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Re: PATCH: += parameter assignments
- X-seq: zsh-workers 16446
- From: Oliver Kiddle <okiddle@xxxxxxxxxxx>
- To: zsh-workers@xxxxxxxxxx
- Subject: Re: PATCH: += parameter assignments
- Date: Mon, 14 Jan 2002 12:45:25 +0000 (GMT)
- Cc: schaefer@xxxxxxxxxxxxxxxx
- Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm
Sorry if you get this twice - I'm resending it after it didn't turn up
first time and sorry if Yahoo re-wraps the text horribly.
Bart Schaefer wrote:
> I'm not entirely happy with the addition of the a+=val syntax because
> conflicts (conceptually, not mechanically) with the += operator that
> already present in the math syntax. Consider that the following:
> integer i=4
> typeset s=4
> print $i $s
> 14 50
What would you have sooner expected - `14 14'?
> However, what I consider to be worse is that:
> print $s
> Interpreting strings as integers in math context makes some sort of
> sense, but doing both that, and also overloading += depending on the
> parameter type, is going too far. I think the suggested change for
> -= would be even more confusing.
I'm not sure that I've entirely understood your argument here as your
example doesn't seem particularly confusing to me. The ((s+=5)) results
in 5 with s remaining a scalar - that was the case before. It remained
a scalar so the s+=5 results in 55.
I don't think it is ideal that the new += can be used for numeric
addition. I find += to be useful with arrays, scalars and associations
and it is these (with the addition of compound variables) for which I
imagine this feature was intended in ksh93. My intention was to
continue to use (( ... )) when dealing with numerics - we could add a
note to recommend this in the documentation.
Have you got any ideas on how to solve this? Short of ditching +=, the
only thing I can think of would be to make scalar+=val identical to
(( scalar+=val )) but I think it would be a pity to lose the appending
to scalars functionality. Does anyone else have any view or ideas?
> type, is going too far. I think the suggested change for -= would be
> even more confusing.
The results might not be imediately obvious after a mix of both the
math and non-math += for scalars but considered on their own I don't
find them "confusing".
> And the following can't be anything but a bug:
A bug maybe, but it has bugger all to do with the += code.
meaning 4.0.4 but 4.1.0-dev-1 behaves as now so the problem will have
been introduced sometime before that. 15292 at a guess as that is the
one in that time frame dealing with math.c.
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