Annoying octal notation

Ben Finney ben+python at benfinney.id.au
Sat Aug 22 02:03:35 CEST 2009


Derek Martin <code at pizzashack.org> writes:

> James Harris wrote:
> > It maybe made sense once but this relic of the past should have been
> > consigned to the waste bin of history long ago.
>
> Sigh. Nonsense. I use octal notation *every day*, for two extremely
> prevalent purposes: file creation umask, and Unix file permissions
> (i.e. the chmod() function/command).

Right. Until Unix stops using these (and whatever replaces it would have
to be pretty compelling, given the prevalence of these in octal
notation), or until people stop using Unix, these will be with us and
require octal notation.

That doesn't mean, of course, that we need to elevate it above
hexadecimal in our language syntax; ‘0o012’ will allow octal notation
for literals just fine.

> I fail to see how 0O012, or even 0o012 is more intelligible than 012.
> The latter reads like a typo

No, it reads like a very common notation for decimal numbers in natural
usage. It's very frequently not a typo, but an expression of a
three-digit decimal number that happens to be less than 100.

> and the former is virtually indistinguishable from 00012, O0012, or
> many other combinations that someone might accidentally type (or
> intentionally type, having to do this in dozens of other programming
> languages).

Only if you type the letter in uppercase. The lower-case ‘o’ is much
easier to distinguish.

Whether or not you find ‘0o012’ easily distinguishable as a non-decimal
notation, it's undoubtedly easier to distinguish than ‘012’.

> I can see how 012 can be confusing to new programmers, but at least
> it's legible, and the great thing about humans is that they can be
> taught (usually). I for one think this change is completely misguided.

These human programmers, whether newbies or long-experienced, also deal
with decimal numbers every day, many of which are presented as a
sequence of digits with leading zeros — and we continue to think of them
as decimal numbers regardless. Having the language syntax opposed to
that is a wart, a cognitive overhead with little benefit, and I'll be
glad to see it go in favour of a clearer syntax.

-- 
 \       “… one of the main causes of the fall of the Roman Empire was |
  `\        that, lacking zero, they had no way to indicate successful |
_o__)                  termination of their C programs.” —Robert Firth |
Ben Finney
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