improve show to handle `;` in a tuple

[vtjnash]

julia> ( :((a,; b)) ) # :/ would be nice for this to round-trip through `show`
:(($(Expr(:parameters, :b)), a))

julia> :( g(a,; b) ) # should print like this, using the same code as handles `:call`:
:(g(a; b))

[mrandri19]

I'd like to take a stab at this, I should be looking in base/show.jl right?

[JeffBezanson]

Thanks, yes that's correct.

[mrandri19]

Ok so I've done some more research:

julia> :(1,;2)
:(($(Expr(:parameters, 2)), 1))

The call stack look like this:

• show_unquoted_quote_expr prints :(
  • show_unquoted prints (
    • show_list
      • show_unquoted prints $(Expr(
        • show prints :parameters
        • show prints , 2

julia> :(f(1,;2))
:(f(1; 2))

The call stack look like this:

• show_unquoted_quote_expr prints :(
  • show_unquoted
    • show_call prints f(
      • show_list prints 1;
      • show_list prints 2

Now, inside show_call there is some logic to print parameter lists:

if !isempty(func_args) && isa(func_args[1], Expr) && func_args[1].head === :parameters
    print(io, op)
    show_list(io, func_args[2:end], ", ", indent)
    print(io, "; ")
    show_list(io, func_args[1].args, ", ", indent)
    print(io, cl)
else
    show_enclosed_list(io, op, func_args, ", ", cl, indent)
end

while in show_unquoted there is not, therefore it falls back to the default case

if unhandled
    print(io, "\$(Expr(")
    show(io, ex.head)
    for arg in args
        print(io, ", ")
        show(io, arg)
    end
    print(io, "))")
end

Should I just add one more elseif case to show_unquoted, copying the code from show_call?
Or should I add the elseif but extracting the show_call code into a function and using the same in both?
Or should I add the elseif and then change show_call to use show_unquoted instead of its custom logic?