[julia-users] Return value discrepancy between `foo[i] = x` and `setindex!(foo, x, i)`

[Kenta Sato]

I thought that `foo[i] = x` is a syntax sugar of `setindex!(foo, x, i)` and 
hence the return values are identical in both cases. This is suggested in a 
section of the manual: 
http://julia.readthedocs.org/en/release-0.3/stdlib/collections/#indexable-collections
.

setindex!(*collection*, *value*, *key...*)
>
> Store the given value at the given key or index within a collection. The 
> syntax a[i,j,...] = x is converted by the compiler to setindex!(a, x, i, 
> j, ...).
>

But the following code doesn't work as such:

type Foo; end

function Base.setindex!(foo::Foo, x, i)
    return 100
end

let
    foo = Foo()
    @show (foo[1] = 1)
    @show (setindex!(foo, 1, 1))
end

Actual:
foo[1] = 1 => 1
setindex!(foo,1,1) => 100


Expected:
foo[1] = 1 => 100
setindex!(foo,1,1) => 100


So my question is which is the intended behavior?
I think it is unreasonable for `setindex!` to ignore the specified return 
value when written as `foo[i] = x` if `foo[i] = x` is really converted to 
`setindex!(foo, x, i)`.