Pow operator precedence

[Russel Winder]

On Fri, 2012-01-13 at 08:09 -0600, Andrew Wiley wrote:
> On Fri, Jan 13, 2012 at 7:47 AM, Manu <turkeyman at gmail.com> wrote:
> > On 13 January 2012 14:48, bearophile <bearophileHUGS at lycos.com> wrote:
> >>
> >> This is the third time I see people trip on power operator precedence:
> >> http://d.puremagic.com/issues/show_bug.cgi?id=7268
> >>
> >> Some people expect this:
> >> (-10 ^^ 2)
> >> To be 100 instead of -100
> >> (Note: Python here uses the same operator precedences.)
> >>
> >> Do you think it's worth (and possible) to help D programmers avoid this
> >> mistake in their code?
> >
> >
> > I would certainly have made this mistake if I tried it. And knowing this
> > information will not cause me to do it properly, it will simply make me
> > question my code, and become very suspicious every time I ever use the
> > operator (ie. I will never understand the proper precedence, I don't think
> > it makes sense).
> > I'm fairly amazed it's not the other way around... what's the logic behind
> > this?
> 
> The logic is that the precedence in the language matches the
> precedence of a written equation.

The problem here is the conflict introduced by allowing -10 to be the
application of the unary minus operator to the positive value 10 instead
of being a representation of the negative integer value -10.  BODMAS
covers everything.


-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at russel.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part
URL: <http://lists.puremagic.com/pipermail/digitalmars-d/attachments/20120113/b1cd7e1a/attachment.pgp>