tidy up dump and xdump

[JeffBezanson]

These functions have become a basket of odd behaviors, and their implementation is quite complex.

There are differences like this:

julia> dump(Int)
Int64

julia> xdump(Int)
Int64::DataType  <: Signed

Then there is this:

julia> dump(1+2im)
Complex{Int64} 
  re: Int64 1
  im: Int64 2

julia> dump((1+2im,{}))
(Complex{Int64},Array{Any,1}) (1 + 2im,{})

The first output was fine, but put it inside a tuple and something else happens.

Also xdump is not documented. If the current behavior does actually make sense, then the task here is to explain it by documenting dump and xdump better.

But I propose that we should only have dump, and it should simply traverse a structure and show everything about it.

[StefanKarpinski]

Solution could be as simple as deleting xdump and deprecating it in favor of dump. If anyone complains we can fix up various broken corner cases in dump.

[ScottPJones]

But would the dump behave as xdump currently does (which seems to supply more information)?
I might take care of this, if nobody else does, since I was just in this code yesterday (#12072) fixing a bug.

[StefanKarpinski]

There should only be one and it should give you all of the information in a somewhat readable form. Currently sometimes dump gives you the information you need while sometimes xdump does. The only way to know seems to be trying it out. It would be great if you fixe that. I suspect no one really depends on this output format, so feel free to change and improve it as you see fit.

[ScottPJones]

Ok, thanks! I've been using dump and xdump a lot lately, so I'll try to come up with something to everybody's satisfaction.

[mauro3]

Buggy with function arguments (similar on jb/functions):

julia> xdump(x->x)
ERROR: ArgumentError: invalid arguments to xdump
 in xdump at show.jl:936

julia> dump(x->x)
(anonymous function)

julia> f(x)=1
f (generic function with 1 method)

julia> xdump(f)
ERROR: ArgumentError: invalid arguments to xdump
 in xdump at show.jl:936

julia> dump(f)
f

[pkofod]

on master Version 0.5.0-dev+2750 (2016-02-19 04:59 UTC)

julia> dump(x->x)
#1
julia> dump(x->x)
#3
julia> dump(x->x)
#5

Is this supposed to say anonymous function as above?