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)?
Sure the auto variable decl allows the declared var to take on the static type
(i.e. as inferred by the compiler), but the programmer still has to know (in
subsequent method invocations applied to the auto var) just what methods are
valid for the statically inferred var type being the subject of the auto decl.
In some ways, as I said above, I miss "D auto" in C++; but then again, when I
explicitly write the exact same type as the function return signature says, I feel more
in control of my software design.
In an ideal world, which in of course such utopia does not really exist, a
pure OO model may well be that of single inheritance, and therefore all methods
would, or could, be forced into a base class and hence, for object/polymorphic
types D'auto keyword would not prove much advantage.
(Pray, let's not get into fragile base class discussions.)
At the end of the day, I'm not sure if D's auto keyword really helps to make my
code more readable to others (alla programming-in-the-large) or if it just
helps me with typing shortcuts (alla programming-in-the-small).
btw. 20 years ago I thought the Forth language was fantastic. Then later I
learned the difference between programming-in-the-small and
programming-in-the-large.
Of course, Forth still hold fond memories for me .. but today I'd still rather
stick to C++.
In writing this NG post, I was wondering about a subject line like "what's the best
thing about D", but then my love/hate relationship with D's auto keyword really got
me.
btw. Do any other languages have an "auto" var idiom? I don't remember Scala
having such (and it's really modern), though perhaps my memory lapses.
Cheers again,
Justin Johansson
"auto" is huge and has a lot to do with programming-at-large. Explicit
types are to generic code as bad as hardcoded magic numbers to regular code.
Andrei
