I think I managed to gain some futher understanding here, but I'm really uncertain if this is correct, so I'd really appreciate if someone who actually understands what's going on would confirm or correct this:
What I *think* happens, is that each time the file is included, a *new* type with the same (fully qualified) name is defined, and a method is added to the function for the new type. For most functions, since the function is also replaced, this doesn't really constitute a problem, but since this code is extending a function from somewhere else, the function isn't replaced, and so methods are just added on top of each other. The main reason it's so confusing is that all the types have the same fully qualified names, so there is really no way for me as a user to know which one of them is the latest version. I think I've seen an issue about this on the tracker, but now I can't find it. Does this seem like a possible explanation of the behavior above? My original problem could then be that I was keeping old variables, of old versions of the type, around - does that also seem reasonable? Thanks, // Tomas On Wednesday, July 16, 2014 1:15:23 PM UTC+2, Tomas Lycken wrote: > > If a I import a function explicitly into a module and extend it with new > methods, Julia seems to become quite confused when I replace the module, > adding more methods with exactly the same signatures as the ones already > there. > > I have a complete gist outlining the problem > <https://gist.github.com/tlycken/ea7781b2eaedccfef12a> (just put all > three files in the same folder and execute julia demo.jl) but in summary, > the oddness is shown if you call methods on the extended function after a > few inclusions: > > julia> methods(Foo.bar) > # 8 methods for generic function "bar": > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(q::Qux) at /home/tlycken/coding/Julia/Baz.jl:11 > bar(x) at /home/tlycken/coding/Julia/Foo.jl:6 > > It still seems to work in this case - bar(Qux(3)) does what it should - > but I’m having trouble in my real application (where I’m extending layer > from Gadfly.jl) because I’m getting MethodErrors for signatures that > methods say are there. > > Is this a known problem? I couldn’t find anything in the issue list on > Github, but I admit that I found it quite difficult to figure out what to > search for… > > // T > >
