On Tue, Nov 06, 2007 at 11:05:58PM +0100, nicolas cellier wrote:
> EndOfStream Exception seems to be unused in 3.10
>
> My understanding was that:
>
>   [[aStream next doSomething] repeat]
>   	on: EndOfStream do: [:exc | exc return: nil].
>
> would be more efficient than testing atEnd at each loop:
> (would only the EndOfStream be signalled!)
>
>   [aStream atEnd]
>   	whileFalse: [aStream next doSomething].

as an aside, Exception handling isn't really squeaky, in that it
is hardly used at all in most code. More commonly used is stuff
like custom control structures:

Dictionary>>at:ifAbsent:
Dictionary>>at:ifPresent:
Object>>ifNil:

You could define this in ReadStream, ReadWriteStream, and maybe
RWTextOrBinaryStream to cover most cases:

nextIfAtEnd: aBlock
    "Primitive. Answer the next object in the Stream represented by the
    receiver. Fail if the collection of this stream is not an Array or a String.
    Fail if the stream is positioned at its end, or if the position is out of
    bounds in the collection. Optional. See Object documentation
    whatIsAPrimitive."

    <primitive: 65>
    position >= readLimit
        ifTrue: [^ aBlock value]
        ifFalse: [^collection at: (position := position + 1)]

> Am I all wrong?
> What do you think?

Just a guess, but blocks are pretty fast, probably faster than
exception handling, and, imho, a lot simpler. Exceptions are
more feature complete, but not commonly needed, imho. And, you
could do "nextIfAtEnd: [EndOfStream signal]" to do error
handling. 

-- 
Matthew Fulmer -- http://mtfulmer.wordpress.com/
Help improve Squeak Documentation: http://wiki.squeak.org/squeak/808