On 9/7/2013 12:30 PM, Andrej Mitrovic wrote:
On 9/7/13, Walter Bright <newshou...@digitalmars.com> wrote:
3. Parameter names need not match.
I disagree with this, because it will practically guarantee that
declarations and definitions go out of sync, which will be *harmful*
for readability (which is partly what this DIP is all about).
Good point.
4. If there is a default parameter value, it may only appear in the member
function declaration.
Also disagreed, because again you can't tell how a function can be
called just by looking at its definition, now you have to go back and
forth between the declaration and the definition to fully understand
how the function works and how it can be used.
How a function is to be *used* should be all there in the *declaration*. Not the
definition.
I didn't mention it in the DIP, and should, that the reason for the default
value to be in the declaration is 1. it should only depend on the declaration's
scope and 2. because all uses of it should rely only on the declaration and 3.
because making an exact duplicate of it in the definition is pointless.
On the other hand, allowing both the declaration and the definition to
have the default values (which must match of course) might have issues
with readability as well:
module a;
enum val = 1;
struct S { void test(int x = val); }
module a_impl;
enum val = 2;
void S.test(int x = val); // a.val or a_impl.val?
If 'val' will always refer to a.val in the declaration module, then
there's no conflict, however it does create a bit of a readability
issue.
Still, I think default values should appear at both sides. It's very
easy to forget you've defaulted a parameter when you start
implementing the function, you could even implement it wrongly.
No, see above.
@safe/@trusted/@system, private/package/public/export access, linkage and
storage classes are as set in the declaration, overriding any in effect for the
definition.
They should both match or there should be an error. Don't allow sloppy
code to be written like that, people *will* read both the declarations
and the definitions (the team or contributors in an open-source
project), and any mismatch will only cause confusion.
I have mixed feelings about this. I think there needs to be just enough in the
definition to match it to the declaration, and nothing else.
