At 11:09 PM 10/1/2010 +0200, Ronny Pfannschmidt wrote:
hi,
I'm implementing a custom pep302 importer in order to ship sets of
python packages within a generated python script,
I'd like to support egg-info entry-points, so I can ship extensions as
well as choose the script entry-point based on the executable name.
However I couldn't find simple docs on doing that.
You need to register some adapters for your importer type, using the
functions described here:
http://peak.telecommunity.com/DevCenter/PkgResources#supporting-custom-importers
Essentially, you will need to define two functions and a class:
def my_finder(path_item, importer, only):
# yield Distribution objects for path
def my_namespace_fixer(importer, path_item, modulename, module):
# return a __path__ entry to add to module
class MyProvider(EggProvider):
def _has(self, path):
# os.path.exists(path)
def _isdir(self,path):
# os.path.isdir(path)
def _listdir(self,path):
# os.listdir(path)
def _get(self, path):
# open(path,'rb').read()
and then register them like so:
register_finder(MyImporter, my_finder)
register_namespace_handler(MyImporter, my_namespace_fixer)
register_loader_type(MyLoaderType, MyProvider)
Without knowing how your PEP 302 importer works, it's hard to get
more specific than this; it all depends on how your sys.path entry
strings are formatted. Are you using a virtual OS path the way .zip
paths work, or something else? (If you're using pseudo-OS paths, you
can reuse pkg_resources.file_ns_handler in place of writing your own
my_namespace_fixer.)
Note, by the way, that if your system doesn't physically place
individual files on disk, you probably actually want something that
emulates .egg rather than .egg-info, as then you can support
resource_filename() operations. (In which case, you'll probably also
subclass ZipProvider rather than EggProvider.)
So, yeah, there are no simple docs. ;-)
It would probably be good if pkg_resources had better support for
rolling your own stuff over a virtual file system; it already has
some, but the "finder" part could be a lot simpler if there was a way
to reuse the built-in ones with a VFS, and the "provider" class would
be easier if the parts of ZipProvider that aren't truly
zipfile-specific were moved to EggProvider or NullProvider.
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