# Boodler: a programmable soundscape tool # Copyright 2007-2011 by Andrew Plotkin # # This program is distributed under the LGPL. # See the LGPL document, or the above URL, for details. """pload: The PackageLoader class. This module contains PackageLoader, which is responsible for loading and tracking the Boodler packages in your collection. (This does not install or modify packages in your collection. The collect module handles those tasks.) """ import sys import os.path import imp import types try: set except: import sets set = sets.Set from boopak import version Filename_Versions = 'Versions' Filename_Metadata = 'Metadata' Filename_Resources = 'Resources' class PackageLoader: """PackageLoader: manages a package collection, loading packages as requested. Also maintains an (in-memory) cache, to speed up load requests. You can also specify extra directories, outside the collection, to load packages from. This class does not deal with writing package files into the collection directory. (For that, see PackageCollection, in collect.py.) The PackageLoader is used in two ways. A Boodler UI will want to call the list_all_current_packages() method, which loads all the descriptive information in the collection. A Boodler sound-playing process will only call the load() method, which loads the particular classes desired. PackageLoader(dirname, boodler_api_vers=None, importing_ok=False) -- constructor Create a PackageLoader, given the name of a directory which contains a collection of packages. If a version is provided (either as a VersionNumber or a string which converts to one), then this is noted as the Boodler version which packages must be compatible with. (As noted in the boodler.api_required metadata field.) (Note that the boodler.api_required field is not checked until the package is actually loaded, which is after version selection occurs. Therefore, it is best if the collection only contains packages which are compatible with the installed Boodler version. None of this is likely to be important, since the Boodler API version is not expected to change much after 2.0.) If the importing_ok flag is false, this loader will refuse to load (that is, execute) Python code in packages. This is the default. Note that only one importing_ok loader can exist in the process. (This is because loaded modules need to be able to find the loader through static variables.) Publicly readable fields: collecdir -- the directory containing the package collection currently_importing -- during an import operation, the package which is being imported (at the moment) Public methods: load() -- load a package, given its name and a version spec load_group() -- load a PackageGroup, given its package name clear_cache() -- erase the PackageLoader's entire knowledge generate_package_path() -- return a pathname in the collection dir add_external_package() -- add an external directory to load a package from remove_external_package() -- remove an external directory clear_external_packages() -- remove all external directories find_all_dependencies() -- determine which packages depend on which others list_all_packages() -- return a list of all the available packages list_all_current_packages() -- list the most recent versions of packages load_package_dependencies() -- load all packages which a package depends on import_package_content() -- import the package's content, if it hasn't been load_item_by_name() -- import and return an item in a package find_item_resources() -- find the Resource for an item in a package attrify_filename() -- given a filename, add its File to the module start_import_recording() -- stub, overridden in PackageCollection stop_import_recording() -- stub, overridden in PackageCollection Internal methods: load_specific() -- load a package, given its name and a specific version discover_all_groups() -- search through the collection directory Class global field: global_loader -- If a PackageLoader can import packages, it needs to be accessible from a global context. (See the package module.) PackageLoader.global_loader is where to find it. """ # The PackageLoader which has importing_ok global_loader = None # This is always None for a PackageLoader; see PackageCollection for # its use. import_recorder = None def __init__(self, collecdir, boodler_api_vers=None, importing_ok=False): if (type(boodler_api_vers) in [str, unicode]): boodler_api_vers = version.VersionNumber(boodler_api_vers) self.boodler_api_vers = boodler_api_vers if (collecdir is None): raise ValueError('PackageLoader requires a collection directory') # We allow the loader to run even without a collection directory, # so that TestSoundAgent will work. #if (not os.path.isdir(collecdir)): # raise ValueError('PackageLoader collection directory is not readable: ' # + collecdir) self.collecdir = collecdir self.importing_ok = False self.module_info = None # Set up the (empty) caches self.package_groups = {} self.package_names = {} self.packages = {} self.external_dirs = {} self.collection_scanned = False self.all_deps = None self.currently_importing = None if (importing_ok): if (PackageLoader.global_loader): raise ValueError('A PackageLoader already exists with importing_ok set') self.importing_ok = True PackageLoader.global_loader = self self.module_info = {} def load(self, pkgname, versionspec=None): """load(pkgname, versionspec=None) -> PackageInfo Load a package, given its name and a version spec. If no second argument is given, the most recent available version of the package is loaded. If the argument is a VersionNumber, that version will be loaded. If it is a VersionSpec, the most recent version that matches the spec will be loaded. A string value will be converted to a VersionSpec (not a VersionNumber). This generates a PackageNotFoundError if no matching package is available. It generates PackageLoadError if the package was malformed in some way which prevented loading. """ if (type(versionspec) in [str, unicode]): versionspec = version.VersionSpec(versionspec) pgroup = self.load_group(pkgname) if (not pgroup.get_num_versions()): raise PackageNotFoundError(pkgname, 'no versions available') if (isinstance(versionspec, version.VersionNumber)): if (not pgroup.has_version(versionspec)): raise PackageNotFoundError(pkgname, 'version \'' + str(versionspec) + '\' not available') vers = versionspec elif ((versionspec is None) or isinstance(versionspec, version.VersionSpec)): vers = pgroup.find_version_match(versionspec) else: raise PackageLoadError(pkgname, 'load spec must be a string, VersionSpec, or VersionNumber') if (not vers): raise PackageNotFoundError(pkgname, 'no version matching \'' + str(versionspec) + '\'') pkg = self.load_specific(pkgname, vers) if (self.currently_importing): # Record what package imported this one, and with what spec self.currently_importing.imported_pkg_specs[pkgname] = versionspec return pkg def load_group(self, pkgname): """load_group(self, pkgname) -> PackageGroup Load a PackageGroup, given its package name. This is not tremendously useful for outside users, although you can call it if you want. A PackageGroup represents all the available versions of a particular package. """ pgroup = self.package_groups.get(pkgname) if (pgroup): return pgroup # Make sure the name is valid. parse_package_name(pkgname) pkgname = str(pkgname) dirname = None versionfile = None # We determine the list of available versions by listing the # package directory in the collection tree. But we have to include # any versions that come in through external directories, too. # Create a list of external versions. external_versions = [] for (name, vers) in self.external_dirs.keys(): if (pkgname == name): external_versions.append(vers) # Find the package directory. (But it's possible that there *is* # no package directory. That's an error, unless we have external # versions -- in which case we keep trucking forward with the # dirname set to None.) dirname = self.generate_package_path(pkgname) if (not os.path.isdir(dirname)): if (not external_versions): raise PackageNotFoundError(pkgname, 'package directory does not exist') dirname = None # Open the Versions file in the package directory. (If we have # a package directory, and a Versions file.) if (dirname): versionfile = os.path.join(dirname, Filename_Versions) if (not os.path.isfile(versionfile)): # We don't raise an exception here, because the install # command needs to tolerate a screwy Collection long # enough to fix it. versionfile = None # Create the PackageGroup object itself. pgroup = PackageGroup(self, pkgname, dirname) fl = None try: if (dirname and versionfile): fl = open(versionfile, 'rbU') # Go through the Versions file and the external versions list # (either of which may be nonexistent). pgroup.discover_versions(fl, external_versions) finally: if (not (fl is None)): fl.close() # Add the new group to the cache. self.package_groups[pkgname] = pgroup return pgroup def load_specific(self, pkgname, vers): """load_specific(pkgname, vers) -> PackageInfo Load a package, given its name and a specific version number. (The version number may be a VersionNumber or a string that can be converted to one.) This is an internal call; external callers should use load(). (load_specific() is intended to be called by a package function which has already consulted package_groups and a PackageGroup object. If you bypass those, you might load a package which is not part of any PackageGroup. That would leave the cache in a confusing state.) """ if (type(vers) in [str, unicode]): vers = version.VersionNumber(vers) pkg = self.packages.get( (pkgname, vers) ) if (pkg): return pkg # Make sure the name is valid. parse_package_name(pkgname) pkgname = str(pkgname) exrec = self.external_dirs.get( (pkgname, vers) ) if (exrec is None): is_external = False dirname = self.generate_package_path(pkgname, vers) else: is_external = True dirname = exrec.dirname # dirname is now the directory where the package should reside. # This may be in the collection or external. if (not os.path.isdir(dirname)): raise PackageNotFoundError(pkgname, 'package version directory does not exist') # Read the metadata. (But if the external directory record has # an overriding Metadata object, use that instead.) if (is_external and exrec.metadata): metadata = exrec.metadata else: metadatafile = os.path.join(dirname, Filename_Metadata) if (not os.path.isfile(metadatafile)): raise PackageLoadError(pkgname, 'package has no metadata file') fl = open(metadatafile, 'rbU') try: metadata = boopak.pinfo.Metadata(pkgname, fl) finally: fl.close() # Read the resources (if there are any). Again, there may be an # overriding Resources object. if (is_external and exrec.resources): resources = exrec.resources else: resourcesfile = os.path.join(dirname, Filename_Resources) if (os.path.isfile(resourcesfile)): fl = open(resourcesfile, 'rbU') try: resources = boopak.pinfo.Resources(pkgname, fl) finally: fl.close() else: # Create an empty resources object resources = boopak.pinfo.Resources(pkgname) # Create the PackageInfo object and look through its metadata. pkg = PackageInfo(self, pkgname, vers, dirname, metadata, resources, is_external) pkg.validate_metadata() # Valid; we can now add it to the cache. self.packages[(pkgname, vers)] = pkg self.package_names[pkg.encoded_name] = pkg return pkg def clear_cache(self): """clear_cache() -> None Erase the PackageLoader's entire knowledge of what groups and packages are available. This should be called whenever packages are added to, modified in, or deleted from the collection directory. """ self.packages.clear() self.package_groups.clear() self.package_names.clear() if (self.all_deps): for dic in self.all_deps: dic.clear() self.all_deps = None self.collection_scanned = False def generate_package_path(self, pkgname, vers=None): """generate_package_path(pkgname, vers=None) -> str Return the pathname in the collection directory which contains the given package group (if vers is None), or the given package (otherwise). This does not create the directory or check for its existence. This is guaranteed to create a distinct pathname for every pkgname or (pkgname, vers) pair. This is true even on case- insensitive filesystems, which is a wrinkle, since version strings are case-sensitive. We work around this by putting a "^" character before each capital letter. """ dirname = os.path.join(self.collecdir, pkgname) if (not (vers is None)): val = str(vers) val = boopak.pinfo.capital_letter_regexp.sub('^\\1', val) dirname = os.path.join(dirname, val) return dirname def add_external_package(self, dirname, metadata=None, resources=None): """add_external_package(dirname, metadata=None, resources=None) -> (str, VersionNumber) Add an external directory to load a package from. The argument must be a complete (unpacked) Boodler directory, with a Metadata file. That package will then be loadable (possibly hiding a package in the collection directory). The metadata and resources fields, if supplied, override the Metadata and Resources files in the directory. (The files do not even have to exist.) If the metadata and resources fields are None, the directory's files are checked as usual. (This override feature is used by the package creation tool. It should not be used for any other purpose.) Returns the name and version of the package that was found. Since this changes the set of what packages are available, it implicitly invokes clear_cache(). The external package facility is not intended to be how most packages are loaded. Most packages should be in the collection directory. You might add an external package in your development workspace (while developing a soundscape), or in a temporary download directory (while deciding whether to install a newly- downloaded package). """ label = '' exrec = ExternalDir(dirname, metadata, resources) if (not os.path.isdir(dirname)): raise PackageLoadError(label, 'not a directory') # Load the metadata file, and see what package/version we are # dealing with. (But only if a metadata object wasn't handed to # us!) if (not metadata): metadatafile = os.path.join(dirname, Filename_Metadata) if (not os.path.isfile(metadatafile)): raise PackageLoadError(label, 'package has no metadata file') fl = open(metadatafile, 'rbU') try: metadata = boopak.pinfo.Metadata(label, fl) finally: fl.close() val = metadata.get_one('boodler.package') if (not val): raise PackageLoadError(label, 'no boodler.package metadata entry') parse_package_name(val) pkgname = str(val) val = metadata.get_one('boodler.version') if (not val): vers = version.VersionNumber() else: vers = version.VersionNumber(val) # Add this to the external directory table. (We have not actually # loaded the package.) self.external_dirs[(pkgname, vers)] = exrec self.clear_cache() return (pkgname, vers) def remove_external_package(self, dirname): """remove_external_package(dirname) -> None Remove an external directory. The argument should be one that was previously passed to add_external_package(). (If it is not a current external directory, this silently does nothing.) Since this changes the set of what packages are available, it implicitly invokes clear_cache(). """ keys = [ key for key in self.external_dirs.keys() if (self.external_dirs[key].dirname == dirname) ] if (not keys): return for key in keys: self.external_dirs.pop(key) self.clear_cache() def clear_external_packages(self): """clear_external_packages() -> None Remove all external directories. Since this changes the set of what packages are available, it implicitly invokes clear_cache(). """ if (not self.external_dirs): return self.external_dirs.clear() self.clear_cache() def discover_all_groups(self): """discover_all_groups() -> None Search through the collection directory, and load all the PackageGroups that are available. This only searches the on-disk directory the first time you call it. To force it to re-scan the directory, call clear_cache() first. """ if (self.collection_scanned): return # This is a little tricky. We go through the collection tree, but # we also have to go through the external directory list. (Because # there might be some external packages that do not correspond # to any group in the collection tree.) dirlist = os.listdir(self.collecdir) for key in dirlist: if (key.startswith('.')): continue dirname = os.path.join(self.collecdir, key) # Directories might appear to have upper-case names, but # the group name must be lower-case. (This will fail to load # an upper-case directory on a case-sensitive filesystem. It # will work in a case-preserving filesystem.) key = key.lower() if (not os.path.isdir(dirname)): continue try: parse_package_name(key) self.load_group(key) except: continue # Go through the external directory list. If the external package # is not already in a loaded group, load its group. (The load_group # method is smart enough to find it, even though there is no # matching directory in the collection tree.) for (name, vers) in self.external_dirs.keys(): if (not self.package_groups.has_key(name)): try: self.load_group(name) except: continue # Now we never need to do this again. (Until the cache is cleared.) self.collection_scanned = True def find_all_dependencies(self): """find_all_dependencies() -> (dict, dict, dict) Go through the entire collection, and determine exactly which packages depend on which other packages. This returns a triple (forward, backward, bad). In the forward dict, each package key (pkgname,vers) maps to an array of package keys which the package depends on. In the backward dict, each package key maps to an array of packages which depend *on* it. In the bad dict, each package key maps to an array of (pkgname,spec) of dependencies which could not be loaded. (In the bad dict tuples, the second element may be None, a VersionSpec, or a VersionNumber.) This only searches the on-disk directory the first time you call it. To force it to re-scan the directory, call clear_cache() first. """ if (self.all_deps): return self.all_deps # We'll need a complete list of groups, first. self.discover_all_groups() forward = {} backward = {} bad = {} # Iterate through every version of every group. for (pkgname, pgroup) in self.package_groups.items(): for vers in pgroup.versions: try: pkg = self.load_specific(pkgname, vers) for (deppkg, depspec) in pkg.dependencies: try: dep = self.load(deppkg, depspec) dict_accumulate(forward, pkg.key, dep.key) dict_accumulate(backward, dep.key, pkg.key) except PackageLoadError, ex: dict_accumulate(bad, pkg.key, (deppkg, depspec)) except PackageLoadError, ex: pass self.all_deps = (forward, backward, bad) return self.all_deps def list_all_packages(self): """list_all_packages() -> list of (str, list of VersionNumber) Search through the collection directory, and return a list of all the available packages. Returns a list of (packagename, list of version) tuples. The top list is in no particular order, but the version list will be sorted newest-to-oldest. This only searches the on-disk directory the first time you call it. To force it to re-scan the directory, call clear_cache() first. """ self.discover_all_groups() res = [] for (pkgname, pgroup) in self.package_groups.items(): ls = [] for vers in pgroup.get_versions(): try: self.load_specific(pkgname, vers) ls.append(vers) except PackageLoadError, ex: pass if (ls): res.append( (pkgname, ls) ) return res def list_all_current_packages(self): """list_all_current_packages() -> list of (str, VersionNumber) Search through the collection directory, and return a list of all the available packages. If multiple versions of a package are available, only the most recent will be listed. Returns a list of (packagename, version) tuples (in no particular order). This only searches the on-disk directory the first time you call it. To force it to re-scan the directory, call clear_cache() first. """ self.discover_all_groups() res = [] for (pkgname, pgroup) in self.package_groups.items(): vers = pgroup.find_version_match() try: self.load_specific(pkgname, vers) res.append( (pkgname, vers) ) except PackageLoadError, ex: pass return res def load_package_dependencies(self, pkg): """load_package_dependencies(pkg) -> (set, dict, int) Attempt to load all the packages which the given package depends on. The argument should be a PackageInfo object. This returns a triple (good, bad, count): - good is a set containing (packagename, version) pairs for every package that was loaded successfully. (This will include the original package.) - bad is a dict. The keys are packagenames which did not load successfully. Each maps to a (nonempty) list of version requests for that package, which could not be fulfilled. (The list contains None, VersionSpecs, and VersionNumbers. Values may occur more than once.) - count is an int, representing how many actual errors occurred. This describes package format problems and read errors. It does not include packages that were simply not available. (The bad dict includes both errors and not-availables; so len(bad) >= count.) If bad is empty, then all dependencies are available. Note that the good list may include more than one version of a package. """ found_ok = set() not_found = {} errors = 0 # Simple breadth-first walk of the dependency tree. to_check = [pkg] found_ok.add(pkg.key) while (to_check): pkg = to_check.pop(0) for (deppkg, depspec) in pkg.dependencies: try: dep = self.load(deppkg, depspec) if (not (dep.key in found_ok)): found_ok.add(dep.key) to_check.append(dep) except PackageLoadError, ex: if (not isinstance(ex, PackageNotFoundError)): errors += 1 dict_accumulate(not_found, deppkg, depspec) return (found_ok, not_found, errors) def import_package_content(self, pkg): """import_package_content(pkg) -> None Import the package's content, if it hasn't already been imported. Warning: this method imports Python source code from the package directory, which means it *executes* Python source code from the package directory. Do not call this on untrusted packages. A sound-player will have to call this, but a package manager should not. """ if (not self.importing_ok): raise Exception('this loader may not import package data!') if (not (pkg.content is None)): return if (pkg.import_in_progress): raise Exception('package imported while import is in progress: ' + pkg.name) attrify_resources = False map_resources = False maincode = pkg.metadata.get_one('boodler.main') if (not maincode): attrify_resources = True (file, pathname, desc) = imp.find_module('emptymodule', boopak.__path__) else: map_resources = True (file, pathname, desc) = imp.find_module(maincode, [pkg.dir]) if (not desc[0] in ['', '.py', '.pyc']): if (file): file.close() raise PackageLoadError(pkg.name, 'module must be .py or .pyc: ' + pathname) # Imports can occur recursively, so we always hold on to the previous # value and restore it afterward. previously_importing = self.currently_importing self.currently_importing = pkg pkg.import_in_progress = True try: mod = imp.load_module(pkg.encoded_name, file, pathname, desc) finally: # Clean up. if (file): file.close() pkg.import_in_progress = False checkpkg = self.currently_importing self.currently_importing = previously_importing if (checkpkg != pkg): raise Exception('import stack unstable: ' + pkg.name) if (attrify_resources): for res in pkg.resources.resources(): filename = res.get_one('boodler.filename') if (filename): self.attrify_filename(pkg, mod, res.key, res, filename) if (map_resources): # Look for declarations in the module which are named in # the resources map. Cache the mapping from the declaration # to the resource object. for res in pkg.resources.resources(): keyls = parse_resource_name(res.key) submod = mod for key in keyls: submod = getattr(submod, key, None) if (submod is None): break if (not (submod is None)): pkg.content_info[submod] = res # The import is complete. self.module_info[mod] = pkg pkg.content = mod def load_item_by_name(self, name, package=None): """load_item_by_name(name, package=None) -> value Given a string that names a resource -- for example, 'com.eblong.example/reptile.Hiss' -- import the module and return the resource object. If the string begins with a slash ('/boodle.builtin.NullAgent') then the regular Python modules are searched. No importing is done in this case; it is really intended only for the contents of boodle.agent. If the string ends with a slash ('com.eblong.example/'), then the module itself is returned. If the package argument is supplied (a PackageInfo object), it becomes the package to look in for unqualified resource names ('reptile.Hiss'). If no package argument is supplied, then an unqualified resource name raises ValueError. """ pos = name.find('/') if (pos < 0): if (package is None): raise ValueError('argument must be of the form package/Resource') mod = package.get_content() elif (pos == 0): # consult Python's module map name = name[ 1 : ] headtail = name.split('.', 1) if (len(headtail) != 2): raise ValueError('argument must be of the form package/Resource') (modname, name) = headtail mod = sys.modules.get(modname) if (mod is None): raise ValueError('not found in Python modules: ' + modname) else: pkgname = name[ : pos ] name = name[ pos+1 : ] pkgspec = None pos = pkgname.find(':') if (pos >= 0): val = pkgname[ pos+1 : ] pkgname = pkgname[ : pos ] if (val.startswith(':')): val = val[ 1 : ] pkgspec = version.VersionNumber(val) else: pkgspec = version.VersionSpec(val) package = self.load(pkgname, pkgspec) mod = package.get_content() if (not name): # "module/" returns the module itself return mod namels = name.split('.') try: res = mod for el in namels: res = getattr(res, el) return res except AttributeError, ex: raise ValueError('unable to load ' + name + ' (' + str(ex) + ')') def find_item_resources(self, obj): """find_item_resources(obj) -> (PackageInfo, Resource) Given an object in a package module, try to find the package, and the Resource that represents the object. If it has no metadata defined, this returns a blank Resource object. This tries to use object attributes such as __module__ and __name__ to identify it. This will work on classes (but not instances) defined in a module; this covers the normal case of Agent classes. It will also work on File objects defined in a module. Beyond that, results are questionable. """ ### rename to "find_item_metadata"? modname = getattr(obj, '__module__', None) if (modname is None): raise ValueError('does not appear to have been defined inside a module: ' + str(obj)) pos = modname.find('.') if (pos < 0): basemodname = modname prefix = None else: basemodname = modname[:pos] prefix = modname[pos+1:] pkg = self.package_names.get(basemodname) if (pkg is None): raise ValueError('does not appear to have been defined inside a Boodler package: ' + str(obj)) # Check the content cache. res = pkg.content_info.get(obj) if (not (res is None)): return (pkg, res) # Look for a Resource we missed. objname = getattr(obj, '__name__', None) if (objname): if (prefix): objname = prefix+'.'+objname res = pkg.resources.get(objname) if (not (res is None)): pkg.content_info[obj] = res return (pkg, res) # Return a blank Resource. if (objname is None): objname = 'UNNAMED' res = boopak.pinfo.Resource(objname) pkg.content_info[obj] = res return (pkg, res) def attrify_filename(self, pkg, mod, wholekey, res, filename): """attrify_filename(pkg, mod, wholekey, res, filename) -> None Given a filename, create a File representing it, and store the File in the module at a location defined by wholekey. Submodules are created as necessary. The res argument is the Resource object associated with wholekey. The filename must be in universal format: relative to the package root, and written with forward slashes, not backslashes. (If the filename is invalid or unsafe, ValueError is raised. However, this does not check whether the file exists.) """ file = pkg.get_file(filename) keyls = parse_resource_name(wholekey) attr = keyls.pop() for key in keyls: submod = getattr(mod, key, None) if (submod is None): # Create an empty submodule. (fl, pathname, desc) = imp.find_module('emptymodule', boopak.__path__) try: submod = imp.load_module(mod.__name__+'.'+key, fl, pathname, desc) finally: # Clean up. if (fl): fl.close() setattr(mod, key, submod) if (type(submod) != types.ModuleType): raise ValueError('resource key based on non-module: ' + wholekey) if (mod.__name__+'.'+key != submod.__name__): raise ValueError('resource key based on imported module: ' + wholekey) mod = submod # We've drilled down so that mod is the next-to-last element # of the original wholekey. setattr(mod, attr, file) file.metadata = res # Set properties analogous to a statically-declared object. This # will help with find_item_resources() later on. file.__module__ = mod.__name__ file.__name__ = attr def start_import_recording(self): """start_import_recording() -> None Stub, overridden in PackageCollection. In a PackageLoader, this does nothing. """ pass def stop_import_recording(self): """stop_import_recording() -> dic Stub, overridden in PackageCollection. In a PackageLoader, this does nothing and returns an empty dict. """ return {} class ExternalDir: """ExternalDir: information about a package directory outside the collection. This is a simple data structure, stored as the values in the loader's external_dirs mapping. ExternalDir(dirname, metadata=None, resources=None) -- constructor The dirname contains the (local) pathname of the directory to consider. The metadata and resources fields, if supplied, override the Metadata and Resources files in the directory. (The files do not even have to exist.) If the metadata and resources fields are None, the directory's files are checked as usual. (This override feature is used by the package creation tool.) Publicly readable fields: dirname -- the directory which contains the package metadata -- the supplied Metadata object (if any) resources -- the supplied Resources object (if any) """ def __init__(self, dirname, metadata=None, resources=None): self.dirname = dirname self.metadata = metadata self.resources = resources class PackageLoadError(Exception): """PackageLoadError: represents a failure to load a package. This represents some kind of internal error or package formatting problem. (If the package simply was not available, the subclass PackageNotFoundError will be used.) """ def __init__(self, pkgname, val='unable to load'): Exception.__init__(self, pkgname + ': ' + val) class PackageNotFoundError(PackageLoadError): """PackageNotFoundError: represents a failure to load a package because it was not in the collection. """ pass # late imports import boopak from boopak.pinfo import dict_accumulate, parse_package_name, parse_resource_name from boopak.pinfo import PackageGroup, PackageInfo