[plt-scheme] Why .dmg for Mac source distributions?

From: Eli Barzilay (eli at barzilay.org)
Date: Thu Sep 10 10:09:40 EDT 2009

On Sep  9, Peter Michaux wrote:
> I have downloaded and installed MzScheme from the Mac source code
> distribution. It really struck me as uncommon that a source is
> distributed in a dmg file. I've been using OS X and installing
> various software for quite a while and haven't encountered a dmg
> being used for this purpose before. A tarball is usual and the same
> tarball is used for *NIX.
> A tarball is certainly easier to deal with from the OS X command
> line.  For the disk image, just getting to the source code requires
> mounting an unmounting the image which causes Finder to flip around
> a bit.

I don't remember how exactly I got to have the osx source
distributions as dmg files -- I probably looked around and found some
projects that did the same.  (Note that I don't use OSX, and I don't
know the conventions.)  Switching to a .tgz or .zip is easy, and if
anyone has an opinion, or better -- knowledge about the right choice,
then please tell me.

On Sep 10, Noel Welsh wrote:
> I find different people use OS X in very different ways. I use it
> like a Unix box w/ Emacs, tarballs etc. Some of my friends use
> little GUI apps when perfectly acceptable CLI apps exist, under
> powered text editors like Smultron etc. Clearly they have weak
> minds. I expect they'd prefer a disk image over a tarball. You can
> always download the Unix src tarball if you want.

The thing is that the unix source won't have the C part of mred for

On Sep 10, Jakub Piotr Cłapa wrote:
> I guess that the main advantage of dmgs is that they can hold any
> metadata OS X can handle (including resource forks and more
> conventional xattrs). This way someone won't break anything by using
> some old tar program for unpacking (most UNIX tools before 10.4 did
> not support any xattrs and resource forks; even cp). This problems
> are not very important for source code.

Right -- and specifically in the plt sources there are no uses of
these.  (Otherwise maintenance of the build/distribute scripts would
have been a PITA.)

> On the other hand the default configuration of Safari automatically
> "unpacks" dmg images just like tar.gz (leaving you with a folder in
> Downloads).

[That might be why I used it...  I don't remember the details, but I
have this vague idea about .dmg files being good for downloading in
some way.]

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!

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