Add clear-cache

[rikhuijzer]

This PR is an attempt to implement clearing of the cache (#14).

EDIT: In a previous version of this comment, I stated that other types than IdDict needed to be considered. Since Base.empty! takes collections, I believe that the code should now work for any relevant type.

[rikhuijzer]

It seems that this PR is not making progress. Is there anything I can do?

[cstjean]

If you do

module A
@memoize foo(x) = x
end

using A: foo

@clear_memoize_cache foo

I don't believe it would work, right? I'm sorry that I didn't think of it earlier.

I think that clear_memoize_cache!(foo) would be the better approach. That means you need to implement Memoize.clear_memoize_cache(::typeof(foo)) in the @memoize expansion.

[cstjean]

Or even better, empty!(memoize_cache(foo)).

[rikhuijzer]

Thank you for looking into it again. Well spotted; no worries, I should have noticed that the functionality wasn't handling modules properly.

I've changed it to empty!(@memoize_cache(foo)) as you've asked. It is a macro call because the module of the caller has to be determined.

The new functionality is also documented again in the README. I've changed a to 2a to change

 julia> @memoize_cache(x)
  IdDict{Any,Any} with 1 entry:
    (1,) => 1

into

 julia> @memoize_cache(x)
  IdDict{Any,Any} with 1 entry:
    (1,) => 2

which I think is more clear to readers.

[cstjean]

I've changed it to empty!(@memoize_cache(foo)) as you've asked. It is a macro call because the module of the caller has to be determined.

I don't think that would work in another module. Try the example I gave:

module A
@memoize foo(x) = x
end

using A: foo
@clear_memoize_cache foo

If you implement memoize_cache(::typeof(foo)), we'll get the behaviour we want, which is that the cache is associated to the function foo, and not to the Symbol foo.

[rikhuijzer]

Isn't that what is tested with

  using .MemoizeTest
  using .MemoizeTest: custom_dict

  empty!(@memoize_cache(custom_dict))
  @test custom_dict(1) == 1
  @test MemoizeTest.run == 3
  @test custom_dict(1) == 1
  @test MemoizeTest.run == 3

  empty!(@memoize_cache(MemoizeTest.custom_dict))
  @test custom_dict(1) == 1
  @test MemoizeTest.run == 4

in the tests? If I understand correctly, this is the example you gave

julia> using Memoize

julia> module A
       using Memoize
       @memoize foo(x) = x
       end
Main.A

julia> using .A: foo

julia> @memoize_cache(foo)
IdDict{Any,Any}()

julia> foo(3)
3

julia> @memoize_cache(foo)
IdDict{Any,Any} with 1 entry:
  (3,) => 3

julia> empty!(@memoize_cache(foo))
IdDict{Any,Any}()

[rikhuijzer]

Oh, and the build appears to be failing on Julia 1.1 with

ERROR: LoadError: "Main.MemoizeTest.custom_dict" is not defined in module Main

It seems that I need to fix that.

[rikhuijzer]

On second thought, I'm not going to invest time on Julia 1.1. I did that at GiovineItalia/Gadfly.jl#1496 and it was not a good time investment.

Let me know if I can make changes to improve the functionality on Julia 1.5. If Julia 1.1 is a must, then feel free to close this PR.

[cstjean]

I wouldn't mind dropping 1.1 if it makes things easier and it's necessary.

[cstjean]

in the tests? If I understand correctly, this is the example you gave

Right, sorry that I didn't read the code properly.

[rikhuijzer]

Right, sorry that I didn't read the code properly.

No problem; it happens

I've now used parentmodule, which is great! 🚀 In Julia 1.1, I get

ERROR: LoadError: UndefVarError: ##Main.MemoizeTest.custom_dict_memoized_cache not defined

In Julia 1.2 the tests pass, so I've bumped the Julia version to 1.2.

[cstjean]

Thanks!

[cstjean]

Will merge when the checks are green again.