`convert`: method isn't called even though atsign-which finds one #8818

timholy · 2014-10-26T11:28:01Z

This could be the same problem as #8631, but now I can trigger it even after pinning Color at 0.3.9 (so it clearly has nothing to do with new Dict syntax).

To debug, I modified these lines to generate some println statements so I know the call chain:

convert{T<:Real,N}(::Type{Array{T}}, img::AbstractImageDirect{T,N}) = convert(Array{T,N}, img)
function convert{T<:ColorType,N}(::Type{Array{T}}, img::AbstractImageDirect{T,N})
    println("here 2")
    convert(Array{T,N}, img)
end
function convert{T,N}(::Type{Array{T,N}}, img::AbstractImageDirect{T,N})
    assert2d(img)  # only well-defined in 2d
    p = permutation_canonical(img)
    dat = convert(Array{T}, data(img))
    if issorted(p)
        return dat
    else
        return permutedims(dat, p)
    end
end
function convert(::Type{Array}, img::AbstractImage)
    println("here 1")
    convert(Array{eltype(img)}, img)
end

Now:

julia> using Images, TestImages

julia> img = testimage("mandrill")
RGB Image with:
  data: 512x512 Array{RGB{UfixedBase{Uint8,8}},2}
  properties:
    IMcs: sRGB
    spatialorder:  x y
    pixelspacing:  1 1

julia> A = convert(Array, img)
ERROR: `convert` has no method matching convert(::Type{Array{T,N}}, ::Image{RGB{UfixedBase{Uint8,8}},2,Array{RGB{UfixedBase{Uint8,8}},2}})
 in convert at base.jl:13

julia> @which convert(Array, img)
convert(::Type{Array{T,N}},img::AbstractImage{T,N}) at /home/tim/.julia/v0.3/Images/src/core.jl:227

So you can see it never calls the method found by @which (it never prints out "here 1").

julia> versioninfo()
Julia Version 0.3.2-pre+36
Commit 275afc8* (2014-10-02 03:42 UTC)
Platform Info:
  System: Linux (x86_64-linux-gnu)
  CPU: Intel(R) Core(TM) i7 CPU       L 640  @ 2.13GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Nehalem)
  LAPACK: libopenblas
  LIBM: libopenlibm
  LLVM: libLLVM-3.3

The text was updated successfully, but these errors were encountered:

timholy · 2014-10-26T12:38:53Z

I just verified that this behavior is present in julia 0.3.0 as well as the latest julia 0.3.3-pre. I swear this worked at one point (you can even see it in the Images README), so I bet it's a bug triggered by a change in a package. I'm going to start going through older versions of Color, since that seems to have triggered other convert problems.

timholy · 2014-10-26T13:20:33Z

Here's a more minimal test case:

In ~/.julia/v0.3/Color, say git checkout 034db53a7c6dcf532d667c91a097d7b84c985ef1
Implement the following:

diff --git a/src/conversions.jl b/src/conversions.jl
index 8c0d2d7..ff0f2c9 100644
--- a/src/conversions.jl
+++ b/src/conversions.jl
@@ -688,6 +688,10 @@ convert{C,T}(::Type{AlphaColorValue{C,T}}, c::AlphaColorValue{C,T}) = c
 function convert{C,T,D,U}(::Type{AlphaColorValue{C,T}}, c::AbstractAlphaColorValue{D,U})
     AlphaColorValue{C,T}(convert(C, c.c), c.alpha)
 end
+function convert{D,T}(AC::TypeConstructor, c::AbstractAlphaColorValue{D,T})
+    AlphaColorValue(convert(colortype(AC), c.c), c.alpha)
+end
+
 convert{C,T}(::Type{AlphaColorValue{C,T}}, c::ColorValue) =
     AlphaColorValue{C,T}(convert(C, c), one(T))

Now test like this:

using Images, TestImages
img = testimage("mandrill")
A = convert(Array, img)

Without that diff, it works fine.

IIRC, the motivation for the TypeConstructor convert method is to support convert(RGBA, c), where RGBA is a typealias.

JeffBezanson · 2014-10-26T16:56:47Z

I'll look at this. But, there should definitely not be definitions for TypeConstructor; that doesn't really make sense. {T<:AlphaColorValue}(::Type{T}) might work instead. I don't know if this is the source of the problem though.

timholy · 2014-10-26T22:08:32Z

That specific change doesn't work: tests fail on convert(RGBA, color("red")). Playing around a bit, I didn't find another variant that works on Julia 0.3, either.

However, it's clearly not the only problem with convert, as commenting out that method does not fix JuliaAttic/Color.jl#68.

aviks · 2014-11-01T23:40:29Z

Using released Color 0.3.10:

./julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "help()" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.3.3-pre+18 (2014-10-28 09:26 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit bdd4597* (4 days old release-0.3)
|__/                   |  x86_64-apple-darwin13.4.0

julia> using Color

julia> convert(Vector{Symbol}, {"a","b"})
ERROR: `convert` has no method matching convert(::Type{Array{Symbol,1}}, ::Array{Any,1})
 in convert at base.jl:13

julia>

Executing the convert method before the import makes the call work even after the import.

./julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "help()" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.3.3-pre+18 (2014-10-28 09:26 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit bdd4597* (4 days old release-0.3)
|__/                   |  x86_64-apple-darwin13.4.0

julia> convert(Vector{Symbol}, {"a","b"})
2-element Array{Symbol,1}:
 :a
 :b

julia> using Color

julia> convert(Vector{Symbol}, {"a","b"})
2-element Array{Symbol,1}:
 :a
 :b

This bug effectively prevents many packages (eg GLM) from working in conjunction with Gadfly. Quite a few of the bugs in packages are linked to #8631 , but given @JeffBezanson 's comment there about 0.4 breakage, I'm uncertain if they are related.

timholy · 2014-11-02T01:09:31Z

"convertalypse" is quite troublesome.

I hope to be able to look at it myself starting Nov 6, but no promises about whether I'll make any progress. In the meantime, I'd definitely recommend experimenting with pinning Color at earlier versions.

aviks · 2014-11-02T01:29:27Z

"convertalypse" indeed!

Pinning Color to 0.3.9 does make the issue go away.

./julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "help()" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.3.3-pre+18 (2014-10-28 09:26 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit bdd4597* (4 days old release-0.3)
|__/                   |  x86_64-apple-darwin13.4.0

julia> using Color

julia> convert(Vector{Symbol}, {"a","b"})
2-element Array{Symbol,1}:
 :a
 :b

Unfortunately, something else in Gadfly causes this to recur. So the issue is not isolated to Color. :(

./julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "help()" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.3.3-pre+18 (2014-10-28 09:26 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit bdd4597* (4 days old release-0.3)
|__/                   |  x86_64-apple-darwin13.4.0

julia> using Gadfly
Warning: could not import Base.has into Gadfly
Warning: could not import StatsBase.bandwidth into Stat
Warning: could not import StatsBase.kde into Stat

julia> convert(Vector{Symbol}, {"a","b"})
ERROR: `convert` has no method matching convert(::Type{Array{Symbol,1}}, ::Array{Any,1})
 in convert at base.jl:13

timholy · 2014-11-03T01:44:56Z

What if you pin to 0.3.6?

aviks · 2014-11-03T18:38:21Z

I recompiled my julia install (as part of trying to git bisect) and now cannot replicate this issue after a using Color even with Color 0.3.10 . However it reliably fails when using Gadfly.

The good news is, with Color pinned to 0.3.6, using Gadfly no longer produces a error with convert

timholy · 2014-11-03T18:51:38Z

I just completed a bisect for a similar problem over at #8631. I'm not certain the two are related, which is why there are two issues, but one can always hope...

aviks · 2014-11-05T18:16:21Z

@timholy Another report that pinning to 0.3.6 fixes it. JuliaStats/MixedModels.jl#26

timholy · 2014-11-07T11:59:31Z

OK, now I know a lot more about this. First, this bug doesn't apply to master, so it's 0.3-specific. Second, the commit that triggered this is e3c5c11. Third, my attempts to fix this (e.g., make it more like the function in master) failed, and I don't understand inference.jl, so I may have to ask @carnaval or @JeffBezanson for advice or help.

A simple test script:

import Base.convert

convert(E::TypeConstructor, e) = error("oops")

immutable Container{T}
    data::Array{T}
end

function convert(::Type{Array}, c::Container)
    println("Here")
    c.data
end

A = Container([5])

and then, at the REPL, do this:

include("<name_of_test_script>")
convert(Array, A)

(I wasn't able to trigger the bug if it's run from a script.)

This should fix numerous related errors in other packages

timholy · 2014-11-07T15:38:01Z

Pkg.free("Color"); Pkg.update() should give you a version of Color that works around this problem.

vtjnash · 2016-07-20T20:47:37Z

should be fixed now

timholy mentioned this issue Oct 26, 2014

Add some missing convert(Array, img) methods JuliaImages/Images.jl#208

Closed

timholy mentioned this issue Oct 26, 2014

New ambiguity warning JuliaAttic/Color.jl#70

Closed

aviks mentioned this issue Nov 1, 2014

error with 'convert' types JuliaStats/MixedModels.jl#26

Closed

timholy mentioned this issue Nov 3, 2014

Pair construction can bork convert #8631

Closed

timholy added a commit to JuliaAttic/Color.jl that referenced this issue Nov 7, 2014

Work around JuliaLang/julia#8818

e880cbf

This should fix numerous related errors in other packages

timholy mentioned this issue Nov 24, 2014

Add _nref method specifically for type inference (fixes #9135) #9139

Closed

garborg mentioned this issue Jan 14, 2015

[WIP] support streaming osm files through libexpat tedsteiner/OpenStreetMap.jl#55

Merged

ihnorton added the bug Indicates an unexpected problem or unintended behavior label Jan 19, 2015

vtjnash closed this as completed Jul 20, 2016

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`convert`: method isn't called even though atsign-which finds one #8818

`convert`: method isn't called even though atsign-which finds one #8818

timholy commented Oct 26, 2014

timholy commented Oct 26, 2014

timholy commented Oct 26, 2014

JeffBezanson commented Oct 26, 2014

timholy commented Oct 26, 2014

aviks commented Nov 1, 2014

timholy commented Nov 2, 2014

aviks commented Nov 2, 2014

timholy commented Nov 3, 2014

aviks commented Nov 3, 2014

timholy commented Nov 3, 2014

aviks commented Nov 5, 2014

timholy commented Nov 7, 2014

timholy commented Nov 7, 2014

vtjnash commented Jul 20, 2016

convert: method isn't called even though atsign-which finds one #8818

convert: method isn't called even though atsign-which finds one #8818

Comments

timholy commented Oct 26, 2014

timholy commented Oct 26, 2014

timholy commented Oct 26, 2014

JeffBezanson commented Oct 26, 2014

timholy commented Oct 26, 2014

aviks commented Nov 1, 2014

timholy commented Nov 2, 2014

aviks commented Nov 2, 2014

timholy commented Nov 3, 2014

aviks commented Nov 3, 2014

timholy commented Nov 3, 2014

aviks commented Nov 5, 2014

timholy commented Nov 7, 2014

timholy commented Nov 7, 2014

vtjnash commented Jul 20, 2016

`convert`: method isn't called even though atsign-which finds one #8818

`convert`: method isn't called even though atsign-which finds one #8818