OpenRCE Blog Entry

Ero Carrera (ero) <ero

carrera

gmail

com>

Thursday, January 8 2009 17:39.00 CST

A couple of interesting things Ive found out lately:

When packaging the latest pefile I noticed the dot-underscore files in the tar.gz. If one extracts the contents there are no such files to be found (if youre working on OSX) while they will show up in other operating systems. Those dot-underscore files are OSX way of storing the resource fork (metainformaion). While it might be handy to keep it around when moving files between Macs, its not nice to have such dot-underscore files show up in other systems. How to get rid of them is not too well documented.

There are two oddly named environment variables (they changed between OSX versions) that control the creation of such files. Setting the following envionment variables to true will make tar not create those dot-underscore files when archiving a file with a resource fork.

COPYFILE_DISABLE
COPY_EXTENDED_ATTRIBUTES_DISABLE

One can just set them in the python setup.py script, so when the source distribution is created, no resource forks are dumped into those files.

import os
os.environ[COPY_EXTENDED_ATTRIBUTES_DISABLE] = true
os.environ[COPYFILE_DISABLE] = true

In my case it was TextMate that was using a resource fork to store some metainformation about the Python files I was working with.

Now a useful tip for subversion. I always knew CVS and subversion had to have such feature but never was able to find how to use, I finally tracked it down.

This might not be knew to anyone that has spent some time with svn... but was to me. The things is, I was sure there had to be a comfortable way of having SVN automatically add the revision number to the source code. That would allow to have version numbers with a revision appended to them automatically, which would make lots of things much nicer, like tracking errors with specific versions.

To achieve that, one can use subversion keywords. SVN will replace those keywords with the appropriate information. In this case the cool one is "$LastChangedRevision$", whereever we write it, it will get replaced by "$LastChangedRevision: XXX $" where XXX is the revision number.

You need to tell subversion you want it to replace that keyword in a given file(s). To do that just issue a: svn propset svn:keywords "Rev" path/to/the/file to set the property on that file.

A practical example for Python code would be:

__revision__ = "$LastChangedRevision$"
__version__ = %d % int( __revision__[21:-2] )

The keyword would be replaced as described above and then we can fetch the revision number and add it to the version number transparently. Subversion will handle it cleanly.