Re: GZip{In,Out}putStream in GIO?

[Mikkel Kamstrup Erlandsen <mikkel kamstrup gmail com>]

2009/8/1 Bastien Nocera <hadess hadess net>:
> On Fri, 2009-07-31 at 21:17 +0100, Alberto Ruiz wrote:
>> 2009/7/31 Brian J. Tarricone <bjt23 cornell edu>:
>> > On 07/31/2009 05:48 AM, Mikkel Kamstrup Erlandsen wrote:
>> >
>> >>  From the looks of it, it should be straight forward to write
>> >> GZip{In,Out}putStream classes based on zlib
>> >
>> > I'd say call it GCompressed{In,Out}putStream and have it either auto-detect
>> > the compression type, or have a param in the API to specify from an enum (or
>> > both).  People can add support for other types of compression as time goes
>> > on.
>>
>> And expand the list of glib dependencies to the infinite?
>> I don't think I like such an idea at this level of the API.
>
> You could claim the same about the gdk-pixbuf loaders, or the gvfs
> backends. The point is that you'd want to make your original class
> flexible enough that people could extend upon it (even if you don't
> start off with a plugin API).
>
> I could think of at least 5 types of compressions that would be useful
> to have without having to use a command-line tool to decompress:
> - gzip for anything and everything that can come from a web server (in
> my case, iTunes Music Store playlist parsing, or more widely, GOffice
> file formats)
> - zip for OpenOffice.org documents and Comic Books (evince)
> - 7zip/LZMA/Xz formats for Comic Books
> - Rar for the same as above
>
> I'd be happy seeing at least the first one, very happy to see the first
> 3, that all have open source implementations, and would provide more
> robust support for those file types in applications.

Ok, taking Brian's ideas into consideration, how about this:
GCompressedInputStream (extrapolate to output streams yourself) is an
abstract base class. It has static factories:

GCompressedInputStream*
g_compressed_inputstream_new_for_type (const gchar* type_name);

GCompressedInputStream*
g_compressed_inputstream_new_for_stream (GInputStream* in);

We have concrete classes for the most used compressions publicly
available, eg. GZip, Zip[1] (and BZip2?). Other compressions can be
registered via GIO extension points (one for compressors and one for
decompressors).

-- 
Cheers,
Mikkel

[1]: Modulo the fact that Zip files can't be parsed as simple streams.
Maybe a GArchive*putStream base class is needed.