Graceful parsing of Colorants

[tbreloff]

This isn't ideal behavior:

julia> using Colors

julia> parse(Colorant, "red")
RGB{U8}(1.0,0.0,0.0)

julia> parse(Colorant, colorant"red")
ERROR: StackOverflowError:
 in parse at /home/tom/.julia/v0.4/Colors/src/parse.jl:136 (repeats 342 times)

Should there be a better signature in parse:

Base.parse{C<:Colorant}(::Type{C}, desc::AbstractString) = convert(C, parse(Colorant, desc))::C

and/or should there be a "pass-through" option for Colorants:

Base.parse{C<:Colorant}(::Type{C}, c::Colorant) = convert(C, c)

[timholy]

FYI colorant"red" by itself (without the parse) is all you need. But a pass-through would be great, if you want to submit that.

[tbreloff]

Yes... The issue came up somewhere in Plots, of course I'm still looking for the bug since the full stack trace isn't printed due to the stack overflow. (Is that a bug in julia?)

I'll put together a PR for the signatures I mentioned.

On Nov 16, 2015, at 11:48 AM, Tim Holy notifications@github.com wrote:

FYI colorant"red" by itself (without the parse) is all you need. But a pass-through would be great, if you want to submit that.

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[timholy]

Ugh, StackOverflows shouldn't happen even in cases of user error, but I often forget to watch out for this.

The key technique is probably to change only one argument type at a time. Comparing

Colors.jl/src/parse.jl

Line 75 in 8309364

function Base.parse(::Type{Colorant}, desc::AbstractString)

and

Colors.jl/src/parse.jl

Line 136 in 8309364

Base.parse{C<:Colorant}(::Type{C}, desc) = convert(C, parse(Colorant, desc))::C

, I'd predict the StackOverflow should go away if you add ::AbstractString to the declaration of desc in the latter. If this is true, would be good to change this.

[timholy]

Fixed by #233