Re: [pclasses-devel] adding zlib/bzip streams support

[stephan b. <st...@s1...>]

On Saturday 01 January 2005 20:51, stephan beal wrote:
> If we could come up with a factory-like approach which works for all
> existing compression formats i think we could do it generically.
> e.g., grab the first 6 bytes of any stream and pass them to to
> Factory<IOStream>::create(). If it can load a factory with that
> cookie, great. That means using binary strings as cookies, but this
> doesn't inherently pose a problem for std::string keys.

i hit send too soon...
was does pose a problem is that we don't know how many bytes we need to 
read to check the cookie. For gz/bz we can do it in 2 bytes. pkzip 
might need more. Tar? XML? This requires logic-based factories, not 
key-based factories, but that requires, AFAICS, explicit knowledge of 
each type which can check this logic (as Christian points out).

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