Implement Base.alignment for our ring element types?

[fingolfin]

I just noticed the differing alignment in this example:

julia> ZZ.([1,23,456])
3-element Vector{ZZRingElem}:
 1
 23
 456

julia> [1,23,456]
3-element Vector{Int64}:
   1
  23
 456

julia> [0, 1//100,23//9,456//17]
4-element Vector{Rational{Int64}}:
   0//1
   1//100
  23//9
 456//17

julia> QQ.([0, 1//100,23//9,456//17])
4-element Vector{QQFieldElem}:
 0
 1//100
 23//9
 456//17

To improve our output, we could implement Base.alignment methods for our ring types.

A naive implementation for our integers and rationals could look like this:

Base.alignment(io::IO, x::ZZRingElem) = (length(string(x)), 0)
Base.alignment(io::IO, x::QQFieldElem) = (length(string(numerator(x))), length(string(denominator(x))))

which results in this output:

julia> ZZ.([1,23,456])
3-element Vector{ZZRingElem}:
   1
  23
 456

julia> QQ.([0, 1//100,23//9,456//17])
4-element Vector{QQFieldElem}:
   0
   1//100
  23//9
 456//17

[lgoettgens]

I like this very much.

Would it even be a good idea to give a default to all RingElem in AA, like base does it for Number

Base.alignment(io::IO, x::RingElem) = (Base.alignment_from_show(io, x), 0)

with some special dispatches for e.g. QQFieldElem.
For ZZRingElem this has the same behaviour as above, for polynomials this looks like the following:

julia> Rx, x = polynomial_ring(GF(2), "x")
(Univariate polynomial ring in x over GF(2), x)

julia> a = x^2+3x-4
x^2 + x

julia> [a,a^2,a^3,a^4,a^5]
5-element Vector{fpPolyRingElem}:
                x^2 + x
              x^4 + x^2
  x^6 + x^5 + x^4 + x^3
              x^8 + x^4
 x^10 + x^9 + x^6 + x^5

If not, I would only do it for certain types like originally proposed, but additionally for things like GF(p) which print like numbers.