Correct module lookup in compat macro

[oxinabox]

@__MODULE__ in the body a macro expands to that macro's module. What one actually wants is the QuoteNode(__module__) which expand to the calling code's module.

module Bar
    macro get_module_wrong()
        mod = @__MODULE__
        :(string($(esc(mod))))
    end

    macro get_module_right()
        mod =  QuoteNode(__module__)
        :(string($(mod)))
    end
end

module Foo
    using ..Bar: @get_module_right, @get_module_wrong

    println("wrong: ", @get_module_wrong())
    println("right: ", @get_module_right())

end;

output:

wrong: Main.Bar
right: Main.Foo

[rofinn]

So this is passing tests because FilePaths has the types we're working with, but this would error for 3rd party types? I'm not entirely sure how we get the Module from this because we need that at macro time rather than when the return expression is evaluated.

[oxinabox]

So this is passing tests because FilePaths has the types we're working with, but this would error for 3rd party types?

Correct

I'm not entirely sure how we get the Module from this because we need that at macro time rather than when the return expression is evaluated.

Oh bother, I forgot that QuoteNode(__module__) does infact return aQuoteNode until it is interpolated.

I think mod = QuoteNode(__module__).value works

[oxinabox]

julia> module Bar
           macro get_module_wrong()
               mod = @__MODULE__
               :(string($(esc(mod))))
           end

           macro get_module_right()
               mod = QuoteNode(__module__).value
               :(string($(esc((mod, typeof(mod))))))
               end
               end
WARNING: replacing module Bar.
Main.Bar

julia> module Foo
           using ..Bar: @get_module_right, @get_module_wrong

           println("wrong: ", @get_module_wrong())
           println("right: ", @get_module_right())

       end;
WARNING: replacing module Foo.
wrong: Main.Bar
right: (Main.Foo, Module)

[rofinn]

I'm a little nervous of using this undocumented language feature.... 😨

[codecov-io]

Codecov Report

Merging #39 into master will not change coverage. The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #39   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           3      3           
  Lines          60     60           
=====================================
  Hits           60     60

Impacted Files	Coverage Δ
src/compat.jl	100% <100%> (ø)	:arrow_up:

---

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Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 9a5eeb4...5a22bad. Read the comment docs.

[rofinn]

Would you mind adding a test case for a 3rd party path type?

Maybe something like this?

using FilePathsBase

struct MyPath <: AbstractPath
    x::String
end

__init__() = register(MyPath)
FilePathsBase.ispathtype(::Type{MyPath}, str) = startswith(str, "mypath://")
...
FilePaths.@compat mypath(path::MyPath) = path.x

And then add this test:

str = "mypath://foo/bar.txt"
p = MyPath(str)
@test TestPkg.mypath(p) == TestPkg.mypath(str)

[oxinabox]

I'm a little nervous of using this undocumented language feature.... 😨

It is documented, it is just poorly documented and kinda obsure.

https://docs.julialang.org/en/v1/manual/metaprogramming/index.html#Macro-invocation-1

[oxinabox]

Test added.

Without my fix, one gets the following errror

FilePaths: Error During Test at /Users/oxinabox/JuliaEnvs/FilePaths.jl/test/runtests.jl:4
  Got exception outside of a @test
  LoadError: LoadError: UndefVarError: MyPath not defined
  Stacktrace:
   [1] _ispath at /Users/oxinabox/JuliaEnvs/FilePaths.jl/src/compat.jl:144 [inlined]
   [2] (::getfield(FilePaths, Symbol("#parse_arg#2")){Module,Array{Symbol,1},Array{Symbol,1}})(::Expr) at /Users/ox
ePaths.jl/src/compat.jl:64
   [3] compat_exp(::Module, ::Expr) at /Users/oxinabox/JuliaEnvs/FilePaths.jl/src/compat.jl:97
   [4] @compat(::LineNumberNode, ::Module, ::Any) at /Users/oxinabox/JuliaEnvs/FilePaths.jl/src/compat.jl:44

With my fix, all things work as expected.

[rofinn]

Awesome, thanks for taking the time to fix this!