On Wednesday, 7 November 2012 at 23:18:41 UTC, Walter Bright
wrote:
One last thing. Sure, string attributes can (and surely would
be) used for different purposes in different libraries. The
presumption is that this would cause a conflict. But would it?
There are two aspects to a UDA - the attribute itself, and the
symbol it is attached to. In order to get the UDA for a symbol,
one has to look up the symbol. There isn't a global repository
of symbols in D. You'd have to say "I want to look in module X
for symbols." Why would you look in module X for an attribute
that you have no reason to believe applies to symbols from X?
How would an attribute for module X's symbols leak out of X on
their own?
Wasn't the @every_body_writes_their_names_like_this in C earlier
in this thread yours? The problem is that without resorting to
some kind of »unique« prefix convention, there will inevitably
be modules X and Y which use the same annotation string for
different purposes, creating problems if both modules are used
together in the same code base (think passing a symbol from X to
a template in Y, or an user wanting to create a type which is
passed to both X and Y).
I feel this is of particular significance here, as I think
attributes are primarily going to be used in this kind of library
context, where you allow the library user to mark their symbols
up in a way that effects your library's behavior on said symbols.
David
