pretty printing structs that contain large array fields

[rambunctiousapple]

Is there a flag to pprint to tell it not to print out large array fields, or to print out the first and last few elements only with an ellipsis ... between? I have structs that contain large vectors. pprint() prints out every element in the vectors which makes the output unreadable.

[xitology]

It is not supported directly, but it is not particularly hard to customize PrettyPrinting to add an ellipsis. For example, you could override PrettyPrinting.quoteof() for your struct types:

using PrettyPrinting
import PrettyPrinting: quoteof

struct S
    v::Vector{Int}
end

quoteof(v::Vector) =
    length(v) <= 2 ?
        Expr(:vect, quoteof.(v)...) :
        Expr(:vect, quoteof(v[1]), :…, quoteof(v[end]))

quoteof(s::S) =
    Expr(:call, :S, quoteof(s.v))

pprintln(S([1,2])) #-> S([1,2])
pprintln(S([1,2,3,4])) #-> S([1, …, 4])

If you want every vector to use this compact notation, you need to add

PrettyPrinting.tile(v::Vector) =
    PrettyPrinting.tile_expr(quoteof(v))

pprintln([[1], [1, 2], [1, 2, 3], [1, 2, 3, 4]]) #-> [[1], …, [1, …, 4]]