We need to kill C syntax for declaring function types

[Don]

Steven Schveighoffer wrote:
> On Mon, 04 Oct 2010 05:07:07 -0400, Don <nospam at 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.