On Tue, Sep 25, 2007 at 11:33:26PM -0700, Andreas Raab wrote:
> 3) Embedding compressed binary data in the midst of text:
> 
> 	stream := RWBinaryOrTextStream on: String new.
> 	stream nextPutAll: 'Binary data: '.
> 	stream binary.
> 	(GZipWriteStream on: stream) nextPut: 123; nextPut: 234; finish.
> 	stream ascii.
> 	stream nextPutAll: 'More data follows' asByteArray.
> 	stream contents.

Ah. I needed to switch the stream *before* I start writing. I
also didn't know about the #finish message.

> All of the above examples work fine.
> 
> >Second, it wouldn't accept the binary data that DataStream was
> >feeding it. It seems to only accept character data, as sending
> >the message #binary to a DeflateStream does nothing.
> 
> DeflateStreams accept binary data if and only if the target stream is 
> binary. They do not allow switching between binary and non-binary in the 
> middle of things.

Didn't know that. Thank you

> >So, should DeflateStreams be general purpose streams, or is
> >there a good reason they are text-only and not embeddable?
> 
> Besides it being not true (as the third example above illustrates) it 
> wouldn't be a problem if it were. You could trivially solve the problem 
> by using:

Sorry for the false assertion.

> writeDelta: aDelta
>     stream nextPutAll: '!DSBinStReader new!'.
>     stream nextPutAll: (DataStream streamedRepresentationOf: aDelta) 
> asString zipped.
> 
> which is not significantly more complex than your solution and actually 
> works - yours doesn't because you either need to #close or #finish the 
> compressor to write the last block (remember LZ is block based). Note 
> that #flush is *not* enough here since the LZ family of compressors 
> marks the last block specifically (#flush will write a block but not 
> mark it as the last block and upset the decompressor on reading it).
> 
> Cheers,
>   - Andreas
> 

Thank you very much. I guess the problem was me not finding or
reading any comments about how to use DeflateStreams.

PS: what is the difference between GZipWriteStream,
ZLibWriteStream, and ZipWriteStream? ZipWriteStream has the
concept of files in an archive, but I couldn't figure out the
first two

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