fix show for OffsetRanges

[jishnub]

Now

julia> a = OffsetVector(axes(OffsetVector(1:10, -5), 1), 5)
OffsetArrays.IdOffsetRange(-4:5) with indices 1:10

julia> axes(a, 1)
OffsetArrays.IdOffsetRange(1:10)

Fixes #198 (comment)

[codecov]

Codecov Report

Merging #200 (837b6d4) into master (3a9b52f) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #200      +/-   ##
==========================================
- Coverage   98.25%   98.25%   -0.01%     
==========================================
  Files           5        5              
  Lines         287      286       -1     
==========================================
- Hits          282      281       -1     
  Misses          5        5              

Impacted Files	Coverage Δ
src/OffsetArrays.jl	97.94% <100.00%> (-0.02%)	⬇️

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[jishnub]

The present way of displaying OffsetRanges is a bit unintuitive, as It's not clear what the type of the object is. Looking at the output, the constructed object appears to be an AbstractRange, but it's not.

Also, conventionally the indices displayed correspond to the outermost wrapper, eg.

julia> ones(3:3, 4:4)
1×1 OffsetArray(::Matrix{Float64}, 3:3, 4:4) with eltype Float64 with indices 3:3×4:4:
 1.0

In the case of OffsetRanges, the outermost wrapper is not displayed, therefore at first glance the indices appear to correspond to the parent range. Copy-pasting the parent range from the display would also not let you obtain the correct type or axes.

Would it be better to display this instead as

julia> a = OffsetVector(axes(OffsetVector(1:10, -5), 1), 5)
OffsetVector(OffsetArrays.IdOffsetRange(-4:5), 1:10) with indices 1:10

This way the output may be copy-pasted as well to create an OffsetRange that is equal to a.

julia> b = OffsetVector(OffsetArrays.IdOffsetRange(-4:5), 1:10);

julia> b == a
true

[timholy]

Fundamentally we just have to work both the indices and values into IdOffsetRange printing (like #179 except not a solution that everyone hates 😄). Conveying the exact types of objects is nice, but conveying their value/behavior is vastly more important. I'd be fine if IdOffsetRange doesn't appear anywhere in the display as long as we know what the indices and values are.

[jishnub]

After 837b6d4 the type of the parent array is not displayed anymore, just the values and the indices.

julia> a = OffsetVector(axes(OffsetVector(1:10, -5), 1), 5)
-4:5 with indices 1:10