2011/10/30 Sven Van Caekenberghe <sven at beta9.be>:
> Nicolas,
>
> On 30 Oct 2011, at 17:07, Nicolas Cellier wrote:
>
>> There is a huge mess in #readFrom: implementation.
>> Some classes will signal trailing characters as a bug, some other
>> won't and will simply leave the stream positioned after the valid
>> part.
>> I propose to change this behaviour uniformly:
>> - readFrom: aStream will never fail on trailing chars (hey, it's a
>> stream, it's up to sender to interpret the tail)
>> - readFromString: aString will always forbid trailing char (it's not a
>> stream, so this garbage is most probably an error and cannot be
>> ignored silently)
>>
>> What do you think ?
>
> Will that not break the idiom (lazy implementation)
>
> readFromString: string
>        ^ self readFrom: string readStream
>
> ?

That's it, I would change for something like

readFromString: aString
    | aStream newInstance |
    aStream := aString readString.
    newInstance := self readFrom: aStream.
    aStream atEnd ifFalse: [FormatError raise].
   ^newInstance


>
> BTW, what I miss in Smalltalk is a way to read from some position to another without all the terrible copying, either from a stream or from a string.
>

There is ReadStream class>>on:from:to: but I recommend testing and
testing again, because Stream implementation is ... not crystal clear.

> Consider parsing something like this '2011-10-30T17:17:47+01:00', the fields are fixed and pretty simple, but I can't think of an efficient way to do it, can you ?
>

Don't know... Some pattern matching, maybe with a simple regexp.
PEG might be simple too.
Qualifying as "efficient" however raise the bar a bit high ;)

Nicolas

> Sven
>
>
>