Thanks, that gets me at least half the way!
However, I still can’t figure out how to give only one warning; if I give
depwarn the symbols :start, :next and :done for the second argument, I get
three warnings - if I give it something custom (and the same to all) I get
three warnings *per element*. How do I give just one warning?
// T
On Sunday, February 21, 2016 at 4:53:19 PM UTC+1, Milan Bouchet-Valat wrote:
Le dimanche 21 février 2016 à 07:30 -0800, Tomas Lycken a écrit :
> > In a package, I have a method foos which currently returns a
> > collection of Bars. This is a little unfortunate, so I would like to
> > instead return a value of type FooCollection on which I can call the
> > bar function to get the array of Bars. I can get backwards
> > compatibility by making FooCollection iterable, by implementing
> > start, next and done. Now, I have the following:
> >
> > immutable Bar end
> > immutable FooCollection
> > bars::Vector{Bar}
> > end
> >
> > foos() = FooCollection(Bar[])
> > bars(fc::FooCollection) = fc.bars
> >
> > start(fc::FooCollection) = start(fc.bars)
> > next(fc::FooCollection, state) = next(fc.bars, state)
> > done(fc::FooCollection, state) = done(fc.bars, state)
> > This works - both the new and the old api:s are supported, and they
> > do the right thing.
> >
> > Next, I’d like to deprecate iteration on FooCollection, to make it
> > obvious to users that although their code isn’t broken, they’re
> > relying on an API that might not work forever. Instead of for bar in
> > foos() I want them to write for bar in bars(foos()). Thus, I make the
> > following changes to the iteration protocol:
> >
> > @deprecate start(fc::FooCollection) start(bars(fc))
> > @deprecate next(fc::FooCollection, state) next(bars(fc), state)
> > @deprecate done(fc::FooCollection, state) done(bars(fc), state)
> > This works and gives deprecation messages when I write for bar in
> > foos() println(bar) end, but the messages aren’t very helpful; for
> > one thing, I get three of them (one for each method), and for another
> > they refer to functions which aren’t present in the user’s code (and
> > which the user won’t realize why they’re called unless they know how
> > to implement iterators in Julia…).
> >
> > Is there a better/more helpful way to do this, without having to re-
> > implement the @deprecate machinery entirely?
> You can call depwarn() directly from inside these functions, and print
> a custom message like "iteration over FooCollection is deprecated". See
> base/deprecated.jl for examples.
>
>
> Regards
>
