don't tab complete deprecated functions

[StefanKarpinski]

It would be really nice if we didn't offer tab completions for functions defined in deprecated. I'm not sure if this is feasible, but since tab completion is a great way to discover things, it's weird when so many things that it reveals are not recommended.

[lindahua]

Whereas this is a good idea, implementation can be problematic.

The problem is that deprecated function is no more than an ordinary function with an warning statement generated by the macro. I am not sure whether there is a programmatic way that can tell "whether a function is deprecated or not".

Also some function is partly deprecated, that is, only deprecated on some combinations of argument types. For such functions, it is still desirable to tab complete the function name. This adds to the complexity of the situation -- we want to know whether the function is completely deprecated.

[JeffBezanson]

Hack: when a function is deprecated using

@deprecate  f  g

it is entirely deprecated, and in that case we could add it to a deprecated list.

[StefanKarpinski]

We could have a DEPRECATED global array and have the @deprecate macro stick a function name in there if the function wasn't already defined. Then tab completion would just filter out things that are in the DEPRECATED list.

[lindahua]

I am not asking to implement this currently, but is it possible to allow attaching metadata to types and functions (in future)? Just like Java's annotation or C#'s attributes. So that people can attach attributes/annotations/what-ever-you-call-it to these things and write programs to inspect them.

[JeffBezanson]

Dup of #3526

[StefanKarpinski]

Well, I may not have the best memory, but at least I'm consistent.