On Monday, 3 November 2014 at 02:43:03 UTC, David Nadlinger wrote:
On Tuesday, 28 October 2014 at 08:29:22 UTC, Jonathan M Davis
via Digitalmars-d wrote:
I see no reason to say anything about the alias syntax in the
style guide.
Consistency, and thus less confusion/mental overhead.
I don't think that you'll be able to make a strong case for
"Either it should be considered fine to use, or we should
deprecate it." If we started with a clean slate today, there
wouldn't be a good reason to include the old syntax. It is an
outlier as we've generally moved away from C-style ordering of
types/declarations, and also can't do inline templates. And if
we agree that the new syntax is to be preferred – and it seems
like except for you we pretty unambiguously do –, I don't see
why we shouldn't put that out as an official recommendation.
Of course, breaking legacy code over this by deprecating the
old syntax might ultimately not be worth it. I don't see how
this can be construed as an argument against putting it in the
style guide, however. In fact, if we planned to deprecate it
anyway, this would rather be a reason _not_ to to bother with
putting it in the style guide first.
To summarize why the new syntax is better than the old one:
- It's more straightforward for newcomers, its order is the
same as for basic assignments. If you somehow find that
unnatural like you've claimed earlier, then you've merely
trained your brain to read alias assignments backwards compared
to assign expressions.
- Arguably the new syntax also makes it easier to skim-read
the code, as the most important part (the symbol introduced) is
at the beginning of the line, not hidden after some potentially
multi-line template instantiation. Granted, you might say that
this is not very relevant, but I think you'd find it hard to
argue that the syntax is _less_ readable.
- The new syntax also has the advantage that it allows to
easily declare template aliases, for example:
---
alias Seq(T...) = T;
---
By the way, "using" is regularly recommended for use in C++11
and up now instead of "typedef" for much the same reasons (just
look at the CppCon talks for some data points).
David
I agree with basically everything you said.
I only have one thing I want to say. The only reason the new
syntax was introduced is because its an improvement on the old,
it would never have been added otherwise. That alone should be
reason enough for it to be prefered.
