Request to change default inner constructors

[quinnj]

#4026 changed the default inner constructor to make calls to convert, a la:

type A
    x::Int64
    #implicit inner constructor
    #A(x) = new(convert(Int64,x))
end

The problem I see with this is that it's too easy to "lose" your only inner constructor for your type.

In  [2]: type A
    a::Int64
end

In  [3]: A(1)

Out [3]: A(1)

In  [4]: A(x) = A(do_my_own_fallback_conversion(x))

Out [4]: A (constructor with 1 method)

In  [5]: A(1.0)

Out [5]: ERROR: stack overflow
while loading In[5], in expression starting on line 1

Luckily, it seems like there's a fairly easy way to make this more intuitive:

type A
    x::Int64
    #implicit inner constructors
    #A(x::Int64) = new(x)
    #A(x) = new(convert(Int64,x))
end

Then when a user thinks to define her own fallback constructor, things don't break!

Reference: https://groups.google.com/forum/#!searchin/julia-dev/gotcha/julia-dev/7WU_HimIsJc/5mj-ns-WN_gJ

[JeffBezanson]

Seems it might be a good idea to provide both by default.

[quinnj]

Thanks Jeff.