On Monday, 22 September 2014 at 14:56:26 UTC, Andrei Alexandrescu
wrote:
On 9/22/14, 2:39 AM, Don wrote:
On Sunday, 21 September 2014 at 18:09:26 UTC, Andrei
Alexandrescu wrote:
On 9/21/14, 8:29 AM, ketmar via Digitalmars-d wrote:
On Sun, 21 Sep 2014 08:15:29 -0700
Andrei Alexandrescu via Digitalmars-d
<[email protected]>
wrote:
alias Int1 = Typedef!(int, "a.Int1");
alias Int2 = Typedef!(int, "b.Int2");
ah, now that's cool. module system? wut? screw it, we have
time-proven
manual prefixing!
Use __MODULE__. -- Andrei
Yes, but you're advocating a hack.
Oh but I very much disagree.
Now you are scaring me. It worries me that this kind of
"solution" can be viewed as acceptable. It's the kind of hacky
code I left C++ to escape from.
People in this thread said it was "ugly" and you dismissed that.
But this isn't just a matter of personal aesthetics.
If you want something objective, it's not DRY, and it's verbose
in a non-trivial way. The hacky design leads to error-prone code.
eg you can easily get a copy-paste bug because it's not DRY.
alias HMENU = Typedef!(void*, __MODULE__ ~ ".HMENU");
alias HFONT = Typedef!(void*, __MODULE__ ~ ".HMENU"); // oops
The original premise does seem to be
correct: library Typedefs are fundamentally broken. The
semantics of
templates does not match what one expects from a typedef: ie,
declaring
a new, unique type.
If you have to pass __MODULE__ in, it's not really a library
solution.
The user code needs to pass in a nasty implementation detail
in order to
get a unique type.
How many libraries did you use that came with no idioms for
their usage?
Describing this as an "idiom" is extremely generous. My standards
are higher.
And it does seem to me, that because it isn't possible to do a
proper
library typedef, you've attempted to redefine what a Typedef
is supposed
to do. And sure, it you remove the requirement to create a
unique type,
Typedef isn't broken.
You're two paragraphs away from "library Typedefs are
fundamentally broken". Now which one is it?
Phobos' Typedef is fundamentally broken, and that your claim that
it is not, relies on moving the goalposts.
But then it isn't very useful, either. You can't,
for example, use it to define the various Windows HANDLEs
(HMENU, etc),
which was one of the most successful use cases for D1's
typedef.
alias HMENU = Typedef!(void*, __MODULE__ ~ ".HMENU");
So please s/can't/can't the same exact way built-in typedef
would have done it/.
No. You can hammer nails in using a rock, but I'm not prepared to
accept a rock as a kind of hammer. It's not a tool that belongs
in any toolbox.
My assertion is, there are no use cases for Phobos's Typedef.
You're always better off doing something else.
