[Seaside-dev] Seaside-Core-topa.811

[Tobias Pape]

Hey,

On 06.04.2014, at 21:58, Philippe Marschall <philippe.marschall at gmail.com> wrote:

> On Sun, Apr 6, 2014 at 8:44 PM, Tobias Pape <Das.Linux at gmx.de> wrote:
>> Hey,
>> 
>> On 06.04.2014, at 19:13, Philippe Marschall <philippe.marschall at gmail.com> wrote:
>> 
>> Hi
>> 
>> Can you elaborate a bit on the problem?
>> Can you supply some tests?
>> Will this work on GemStone (comparing classes with #==)?
>> 
>> This is a strange thing no matter how we look at it.
>> 
>> #pathStringUnencoded states
>> "allocate with correct size, avoid copy"
>> 
>> However, it is working on strings that potentially contain
>> unicode stuff.
> 
> So?
> 
>> The way this method was written did not cope for
>> the underlying stream/stream’s collection to change.
> 
> How so? The type of collection should not have an influence on the
> semantics of #size and if the kind is changed then #becomeForward: is
> used and the collection is replaced in place.

If we were operating on a string, directly, yes.
But can we _Really_ know this for a stream? A stream can do on
its collection what it wants.

> 
>> The test will
>> fail in mostly any squeak out there (except trunk [1]).
> 
> Why?
> 

Because when using a write stream on a byte string and putting
a wide character onto it, the write stream would pro-actively
replace its own underlying collection with a wide one, _NOT_ doing
a #becomeForward:/#become: at all.

>> Yet, we can only be sure that
>> a) the preallocated size is correct and
> 
> This is always the case.
>> b) the #pathUnencodedOn: will not change the collection kind
>> if all path segments are of the same kind (Byte/Wide in Squeak/Pharo
>> or one of the equivalent Unicode classes in GemStone…)
> 
> Um no. The type of collection still changes if all the elements are
> made of WideString in Squeak/Pharo because the initial allocation will
> be done with String new: which gives a ByteString instance which will
> later change to a WideString.

But you cannot be sure to get the collection back you put in (see above).
I also do not think that this is the contract of WriteStream.

I asked a few long-time smalltalkers who said they would not expect the underlying
collection to stay the same if you put not-directly-compatible things in there.

I mean, it wouldn't work after all if you used ByteArray and numbers >256 here.
The case would be the same.


> 
>> Even if the #== in GemStone would fail[2], the failsafe method I
>> added will always work, although potentially create a copy.
>> 
>> 
>> I find it hard to come up with a dedicated test for that except for what
>> already is done in WAUtf8UrlTest>>#testPathStringUnencoded (the one that
>> triggered all that for me).
> 
> If that failed then that's fine.

Ah, ok :)

> Which version of Squeak was that 4.4? 4.5?

Both.
Squeak Trunk is save-ish.

Best
	-Tobias
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