On 01/13/2010 08:46 PM, retard wrote:
Wed, 13 Jan 2010 20:22:02 +0100, Lutger wrote:
On 01/13/2010 05:49 PM, Justin Johansson wrote:
Happy New Year 2010 Everybody.
Having resumed C++ nationality for the last few months, I kind of miss
D's auto keyword.
I am wondering, though, from an OO/polymorphism perspective, and UML
and sound software engineering perspective as well, what does D's auto
keyword buy you except (perhaps) laziness (in keystrokes)?
A lot:
No types to be seen here (aside from the literal 2) so you can: 1.
rename the type whatever bar() returns without ripple effects through
this code
2. substitute the type itself for another type that obeys the same
structural interface.
In a way, it's like not using magic numbers only applied to types :) The
benefits are not limited too but more pronounced in templated code.
The main benefit IMO is that you don't need to repeat things twice.
sadklaskdjlaj<aslfkjals, asdkjasldjw<asldjalsdm, asdjslk>> foo = new
sadklaskdjlaj<aslfkjals, asdkjasldjw<asldjalsdm, asdjslk>>(); // no thanks
Repetition happens every time one uses advanced data structures like
lists, hashes, tuples etc. In cases like
auto foo = bar(2);
auto baz = grok(foo);
I would actually explicitly write to type some times to document things
better.
Well I usually don't use names such as foo, bar and baz in production
code ;) (I suck at naming and have recently started to make long names).
I get your point but would consider that kind of repetition the least of
the benefits, since there is no big downside here to copy & paste away.
All ML derived languages do this much more extensively and they even
don't need an auto keyword for it. C# has var and VB.NET has Dim which
mean the same thing. The nice thing with those languages is that if you
code in Visual Studio, you only have to hover above the variabele and
the type pops up. Most IDE's have this btw, including descent, so that
takes away the concern of having to remember the flow of types inferred.
A tru 1337 koder uses vim or emacs, both of which suck at semantic
analysis :)
Then again, such a koder don't need no pedantic type declarations for
reminders.
