REPL goes into an endless loop while displaying mutually referencing items

[amitmurthy]

type A
    text
    child
    parent

    A() = new("", nothing, nothing)
end

a = A()
a.text="1"
a.child = A()
a.child.text="1.1"
a.child.parent = a

show endlessly tries to display both the child and parent.

Ran into this situation while I was modelling an XML document as a tree structure and I had a parent reference for unwinding the stack while parsing the XML document.

I'll find a workaround for my current use case, but it will be good to enhance show to keep track of objects already displayed and not display them again.

[quinnj]

I think this has actually been around since issue #25.

[toivoh]

See also #1139. I'd also like to see this fixed, but it's not quite clear which is the best way to do it. Just getting rid of the infinite loop would be a start, of course.

[mauro3]

This may be related, however the stackoverflow occurs without doing any displaying:

a=Dict();
a[a]=5;
a[a]=6; # stack overflow

Note this works with ObjectIdDict (but the displaying still crashes julia)

[quinnj]

Closed by #3831.