Support "partial dispatch" matches

[timholy]

Using the example at MichaelHatherly/Docile.jl#38, suppose I wanted to get help for all push! methods associated with a MyObject. It would be nice to be able to say query(push!, (MyObject,)) or @query push!(myobject), without needing to exactly match the rest of the argument types.

If this can be achieved (and I think my own fledgling efforts at something like Docile, JuliaLang/julia#1619, did something like this), then I think MichaelHatherly/Docile.jl#38 becomes much less important.

[MichaelHatherly]

The method version sounds good to me. I assume that Base.tintersect has since been renamed to Base.typeintersect? https://github.com/JuliaLang/julia/pull/1619/files#diff-c20eb2eead14027fab4293e10bacf73bR543.

@query was always meant to have behaviour similar to @which and match an actual method call. I'll try it out as well though and see how it feels.

[MichaelHatherly]

@timholy there's basic partial matching for signatures in query now. @query still behaves as before, since I found that having both partial (query) and exact (@query) matching useful. Give me a shout it's not the behaviour you were after.

[timholy]

It works beautifully. Thanks!

[MichaelHatherly]

Great!