On 2010-01-28 17:27:58 -0500, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> said:
The problem is not localized change. The result of stdin.byLine changes
the _entire_ stdin.
No. Calling byLine doesn't change the stream. It returns a different
view of stdin, which can be used to modify the stream, or not. I think
it should be a property. If it was 'getNextLine' then it should be a
function. As a proof, this doesn't have any effect:
stdin.byLine;
If you put it in a foreach loop, then it has an effect. But it's
foreach that has the effect of calling popFront on the byLine view of
stdin. Getting byLine by itself doesn't do anything.
Another term I'd use for a property, perhaps a better one, is an
'accessor'. A property, or an accessor, gives you access to an aspect
of the object you're dealing with. In the case above, you get access to
stdin line by line. Getting access to something might allow you to
modify it, or it may not, depending on what it is exactly. But just
getting access to it doesn't modify the object in itself.
Sorry to arrive late in this conversation. Let me address some other points:
I know not everyone get it right all the time. But that's not
necessarily a contradiction, it just means that the concept isn't
really well understood. If there was a good definition for it from an
authoritative reference, it might help reduce the confusion. Currently
the only authoritative element seems to be the syntax, no wonder it's
confusing.
Andrei, you keep complaining it's a convention. It *is* a convention,
because only a convention can differentiate actions from accessors.
Ideally, we wouldn't need a special syntax: English words would be
enough. But as you know English words alone are often ambiguous.
Either the convention is (1) how we name things -- like isEmpty vs.
empty -- but I think you don't like that. Either it's (2) a syntactic
convention -- empty vs. empty() -- but then the meaning becomes a
little more subtle. Or (3) you can give the same meaning to both empty
and empty(), but then people are left to guess what it means (action or
accessor), and it creates incongruities with callables. Or (4) you can
force empty() to always be with parenthesis and let people guess what
it means; at least you don't have incongruities.
There's no perfect solution. But of all of these options, the one used
in D1 (number 3) has the most drawbacks: you can't distinguish actions
from accessors, and on top of that you have problems with returning
callables.
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
