Re: cl-defstruct-based package.el, now with ert tests!

[Stephen J. Turnbull]

Daniel Hackney writes:
 > Ted Zlatanov <tzz <at> lifelogs.com> writes:
 > > Agreed, maybe Daniel can explain why using `tar-mode' was questionable.
 > > Performance?
 > 
 > The answer is "it seemed yucky." `tar-mode' was clearly not
 > intended to act as an API for other programs looking to read tar
 > files, so using it as such was kind of hacky. Using the external
 > "tar" program seems like the cleaner alternative.

FWIW, nobody has ever complained about XEmacs's assumption that users
have tar and gzip available to install packages.  (In fact, use of an
external ftp program to perform FTP for distribution has caused a lot
of problems over the years due to firewalls and issues with
configuration of passive FTP.  But no problems with tar and gzip, and
not with ftp the program that I can recall.)

 > Since package.el already uses the external tar program for
 > `package-tar-file-info', I figured depending on tar for more
 > substantial stuff was fine. If people really don't want to depend
 > on the external program, I'll remove it and just use `tar-mode'.
 > 
 > Is there any way to gunzip the data in a buffer without using an external
 > program? It would be nice to be able to use tar.gz files.

Is that the right question to ask?  It would not be hard to link in
zlib to do this, but it creates an additional *dependency*.  So I
think the question is "without external dependencies".  I suspect an
elisp implementation of gunzip would be pretty slow and possibly hard
to get right.