Steven Schveighoffer wrote:
On Mon, 04 Oct 2010 05:07:07 -0400, Don <nos...@nospam.com> wrote:
A great example of how C syntax is hurting us.
---
I found this bit of code in std.container, inside BinaryHeap:
size_t insert(ElementType!Store value)
{
static if (is(_store.insertBack(value)))
{
...
}
else ...
What does the static if do? It's *intended* to check if _store has a
member function insertBack(), which accepts type of a 'value'.
But instead, it ALWAYS silently does the 'else' clause.
Unless _store.insertBack is a valid *type*, (eg, alias int insertBack;).
In which case it gives an error "declaration value is already defined".
I'm really confused here. I could have sworn I've seen compile time
checks like this everywhere. Is the "bug" that's unflagged by the
compiler that you are missing a typeof(...)?
Yes.
Why?
This happens because
x(y); is valid C syntax for declaring a type 'y', such that &y is of
type 'x function()'.
Wait, I thought when declaring a function pointer, you had to have the
(*) in there? Plus I thought you had to have an extra set of
parentheses? I've never seen this before.
Trying...
Oh, that's freaking awful. x(y); silently compiles into something
useless, you need to declare it with a typedef in order to use it (and
even then, it's horrible). It's like accepting the line
int;
Yes, 100% agree, get rid of this. Does that mean we need to get rid of
C-style function pointer declarations? Because I recently saw a use for
them (deciphering C-style function pointer syntax).
I agree, I use it for the same thing. In the patch, I made C-style
function pointers deprecated (so you can still compile it with the -d
switch) and C-style abominable x(y) types illegal.
I would expect that it always remains a deprecated syntax, to aid
conversion of C-style code. But in my experience, you always want to get
rid of them eventually.
