Ary Borenszweig wrote:
Don escribió:
grauzone wrote:
Don wrote:
Ary Borenszweig wrote:
http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP6
This looks like a solution in search of a problem. What's the
problem being solved?
Attaching additional data to types, that can't be specified
otherwhere. This should help with metaprogramming-like stuff.
For example serialization. How do you specify that a field shouldn't
be part of the serialized data? Java has an extra keyword attribute like
"transient" (comes from before attributes were introduced). C# uses
what we call annotation in this thread. How would you do this in D?
I agree that there doesn't seem to be a nice way at present. One
possibility would be to establish a naming convention for transient
fields -- a Ruby-style solution, I guess.
But are annotations actually an ideal solution for this problem?
Presumably, you'll have to specify that somewhere else anyway. I mean,
during reading it will need to either be initialized separately after
serialisation (like opPostBlit, perhaps?), or else remain
uninitialized. Serialisation seems to be _extremely_ similar to
construction. I'm not sure that annotations capture that.
D has much more powerful metaprogramming than C# or Java, so my
intuition and hope is that we shouldn't need to adopt hacks from those
weaker languages. The annotation syntax in C# and Java looks like an
ugly hack to me. Purely a subjective opinion, of course, but it seems
really out of place in a C-family language.
Attributes has many, many other uses. Appart from serialization, you
could specify how a field is stored in a database. How a method maps to
an http request (post, get, which parameters to bind to the request,
etc.). Whether a method should do security checks before executing.
Whether a method should be run as a test, and what's the expected
exception to be thrown. [insert your usage here]
Great, you've answered my question. That should be in the DIP, instead
of the vague stuff that's in there now -- the existing DIP is about
replacing keywords, which is very unconvincing. (It doesn't work,
actually -- the name mangling is important for most of the keywords
mentioned).
