More default_type_parameters definitions

[mtfishman]

This defines missing overloads of default_type_parameters for array types in package extensions.

In addition, it defines a fallback definition using a similar logic to #31. As an example, the package doesn't explicitly define a default_type_parameters overload for LinearAlgebra.Diagonal but with this PR we get:

julia> using TypeParameterAccessors: default_type_parameters

julia> using LinearAlgebra: Diagonal

julia> default_type_parameters(Diagonal)
(Float64, TypeParameterAccessors.UndefinedDefaultTypeParameter())

julia> default_type_parameters(Diagonal, 1)
Float64

julia> default_type_parameters(Diagonal, 2)
ERROR: No default parameter defined at this position.
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] default_type_parameters(::Type{Diagonal}, ::TypeParameterAccessors.Position{2})
   @ TypeParameterAccessors ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:258
 [3] default_type_parameters(::Type{Diagonal}, pos::Int64)
   @ TypeParameterAccessors ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:253
 [4] top-level scope
   @ REPL[7]:1

julia> default_type_parameters(Diagonal, eltype)
Float64

julia> default_type_parameters(Diagonal, ndims)
ERROR: Position not found.
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] #s1#1
   @ ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:76 [inlined]
 [3] var"#s1#1"(T::Any, ::Any, ::Any, supertype_pos::Any)
   @ TypeParameterAccessors ./none:0
 [4] (::Core.GeneratedFunctionStub)(::UInt64, ::LineNumberNode, ::Any, ::Vararg{Any})
   @ Core ./boot.jl:707
 [5] position_from_supertype(type::Type, name::Function)
   @ TypeParameterAccessors ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:47
 [6] position(type::Type, name::Function)
   @ TypeParameterAccessors ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:37
 [7] default_type_parameters(::Type{Diagonal}, pos::Function)
   @ TypeParameterAccessors ~/.julia/dev/TypeParameterAccessors/src/type_parameters.jl:253
 [8] top-level scope
   @ REPL[9]:1

Note that it only defines default parameters that are defined for a supertype (in this case, AbstractArray defines defaults for eltype and ndims). Undefined parameters are output as TypeParameterAccessors.UndefinedDefaultTypeParameter(), which when accessed by position throws an error.

I'm open to suggestions about other ways to design that. It seems reasonable, at least with the current design, since types may not want to define defaults for every type parameter, though probably we could rethink that design with #27.

Todo:

• Add tests.

[codecov]

Codecov Report

Attention: Patch coverage is 73.68421% with 10 lines in your changes missing coverage. Please review.

Project coverage is 82.40%. Comparing base (2402cc8) to head (0b20716).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
ext/TypeParameterAccessorsAMDGPUExt.jl	0.00%	2 Missing ⚠️
ext/TypeParameterAccessorsCUDAExt.jl	0.00%	2 Missing ⚠️
ext/TypeParameterAccessorsMetalExt.jl	0.00%	2 Missing ⚠️
ext/TypeParameterAccessorsStridedViewsExt.jl	0.00%	2 Missing ⚠️
ext/TypeParameterAccessorsoneAPIExt.jl	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
- Coverage   83.41%   82.40%   -1.02%     
==========================================
  Files          14       14              
  Lines         217      250      +33     
==========================================
+ Hits          181      206      +25     
- Misses         36       44       +8     

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docs	39.02% <8.10%> (-4.91%)	⬇️

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[kmp5VT]

Everything looks good to me. Thanks!