Vote for the new std.hash (oops, std.digest)

[Johannes Pfau]

Am Sun, 26 Aug 2012 13:19:35 +0300
schrieb Manu <turkeyman at gmail.com>:

> Looks good, though one thing annoys me as always throughout the D
> docs, liberal use of auto can make them very difficult to understand.
> 
> auto result = hash.finish();
> 
> >From the examples where this appears, I have absolutely no idea what
> 'result' could possibly be and what I can do with it, and you're
> forcing me to go and dig further for that information (waste of time).
> Surely there would be no harm in just writing the type there for
> clarity?
> 
> <rant>
> I'd personally like to see auto abolished, or at least heavily
> discouraged for the sake of clarity from code examples throughout the
> docs. I'm constantly having to chase up what auto's may resolve to
> when reading examples >_<
> You may argue this demonstrated un-idiomatic code, and my trouble is
> due to inexperience; I ask, who is most likely to be reading docs?
> 

OK, I'll fix this if std.digest is accepted into phobos.

However, in this example auto is not just used for convenience, it has
an actual use case:

As documented here
http://dl.dropbox.com/u/24218791/d/phobos/std_digest_digest.html#ExampleDigest
(finish method) the type returned by finish can differ between different
hash implementations. It's always a static array of ubyte, but for crc
it's ubyte[4] for sha1 it's ubyte[20] and for md5 it's ubyte[16]. So
in templated methods, auto is more generic than hardcoding a type. The
equivalent to auto is using digestType!Digest, so

auto result = hash.finish();
digestType!(typeof(hash)) result = hash.finish();

are equivalent. But 

ubyte[4] result = hash.finish();

does only work if hash is a CRC32 digest. It does not work for md5, sha1
digests, etc.

But I agree that examples are easier to read without auto, so I'll
change them to use the explicit type where possible.