write on IOBuffer with a maxsize

[amitmurthy]

Currently, a write on a full IOBuffer, just returns 0.

julia> io=IOBuffer(1)
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=0, maxsize=1, ptr=1, mark=-1)

julia> write(io, uint8(1))
1

julia> write(io, uint8(1))
0

julia> write(io, "Hello")
0

If this is by design, then we should update the documentation to highlight it. Else we should throw an error.

My preference would be for the latter.

[JeffBezanson]

An error could be very useful for limited-output printing, as in #9481 and #10256

[tkelman]

doesn't seem release-blocking

[brenhinkeller]

Looks like this is still true as of 1.8.3:

julia> io=IOBuffer(maxsize=1)
IOBuffer(data=UInt8[...], readable=true, writable=true, seekable=true, append=false, size=0, maxsize=1, ptr=1, mark=-1)

julia> write(io, UInt8(1))
1

julia> write(io, UInt8(1))
0

julia> write(io, UInt8(1))
0

which I suppose effectively means that this is either now the intended behavior and can possibly be closed, or if not could be added to the 2.0 milestone?