gluon.custom_import 源代码

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
| This file is part of the web2py Web Framework
| Copyrighted by Massimo Di Pierro <mdipierro@cs.depaul.edu>
| License: LGPLv3 (http://www.gnu.org/licenses/lgpl.html)

Support for smart import syntax for web2py applications
-------------------------------------------------------
"""
from gluon._compat import builtin, unicodeT, to_native, reload
import os
import sys
import threading
from gluon import current

NATIVE_IMPORTER = builtin.__import__
INVALID_MODULES = set(('', 'gluon', 'applications', 'custom_import'))

# backward compatibility API

[文档]def custom_import_install(): if builtin.__import__ == NATIVE_IMPORTER: INVALID_MODULES.update(sys.modules.keys()) builtin.__import__ = custom_importer
[文档]def track_changes(track=True): assert track in (True, False), "must be True or False" current.request._custom_import_track_changes = track
[文档]def is_tracking_changes(): return current.request._custom_import_track_changes
# see https://docs.python.org/3/library/functions.html#__import__ # Changed in Python 3.3: Negative values for level are no longer supported, # which also changes the default value to 0 (was -1) _DEFAULT_LEVEL = 0 if sys.version_info[:2] >= (3, 3) else -1
[文档]def custom_importer(name, globals={}, locals=None, fromlist=(), level=_DEFAULT_LEVEL): """ web2py's custom importer. It behaves like the standard Python importer but it tries to transform import statements as something like "import applications.app_name.modules.x". If the import fails, it falls back on builtin importer. """ # support for non-ascii name if isinstance(name, unicodeT): name = to_native(name) if hasattr(current, 'request') \ and level <= 0 \ and name.partition('.')[0] not in INVALID_MODULES: # absolute import from application code try: return NATIVE_IMPORTER(name, globals, locals, fromlist, level) except (ImportError, KeyError): pass if current.request._custom_import_track_changes: base_importer = TRACK_IMPORTER else: base_importer = NATIVE_IMPORTER # rstrip for backward compatibility items = current.request.folder.rstrip(os.sep).split(os.sep) modules_prefix = '.'.join(items[-2:]) + '.modules' if not fromlist: # "import x" or "import x.y" result = None for itemname in name.split("."): new_mod = base_importer( modules_prefix, globals, locals, (itemname,), level) modules_prefix += "." + itemname if result is None: try: result = sys.modules[modules_prefix] except KeyError: raise ImportError("No module named %s" % modules_prefix) return result else: # "from x import a, b, ..." pname = "%s.%s" % (modules_prefix, name) return base_importer(pname, globals, locals, fromlist, level) return NATIVE_IMPORTER(name, globals, locals, fromlist, level)
[文档]class TrackImporter(object): """ An importer tracking the date of the module files and reloading them when they are changed. """ THREAD_LOCAL = threading.local() PACKAGE_PATH_SUFFIX = os.path.sep + "__init__.py" def __init__(self): self._import_dates = {} # Import dates of the files of the modules def __call__(self, name, globals={}, locals=None, fromlist=(), level=_DEFAULT_LEVEL): """ The import method itself. """ # Check the date and reload if needed: self._update_dates(name, globals, locals, fromlist, level) # Try to load the module and update the dates if it works: result = NATIVE_IMPORTER(name, globals, locals, fromlist, level) # Module maybe loaded for the 1st time so we need to set the date self._update_dates(name, globals, locals, fromlist, level) return result def _update_dates(self, name, globals, locals, fromlist, level): """ Update all the dates associated to the statement import. A single import statement may import many modules. """ self._reload_check(name, globals, locals, level) for fromlist_name in fromlist or []: pname = "%s.%s" % (name, fromlist_name) self._reload_check(pname, globals, locals, level) def _reload_check(self, name, globals, locals, level): """ Update the date associated to the module and reload the module if the file changed. """ module = sys.modules.get(name) file = self._get_module_file(module) if file: date = self._import_dates.get(file) new_date = None reload_mod = False mod_to_pack = False # Module turning into a package? (special case) try: new_date = os.path.getmtime(file) except: self._import_dates.pop(file, None) # Clean up # Handle module changing in package and # package changing in module: if file.endswith(".py"): # Get path without file ext: file = os.path.splitext(file)[0] reload_mod = os.path.isdir(file) \ and os.path.isfile(file + self.PACKAGE_PATH_SUFFIX) mod_to_pack = reload_mod else: # Package turning into module? file += ".py" reload_mod = os.path.isfile(file) if reload_mod: new_date = os.path.getmtime(file) # Refresh file date if reload_mod or not date or new_date > date: self._import_dates[file] = new_date if reload_mod or (date and new_date > date): if mod_to_pack: # Module turning into a package: mod_name = module.__name__ del sys.modules[mod_name] # Delete the module # Reload the module: NATIVE_IMPORTER(mod_name, globals, locals, [], level) else: reload(module) def _get_module_file(self, module): """ Get the absolute path file associated to the module or None. """ file = getattr(module, "__file__", None) if file: # Make path absolute if not: file = os.path.splitext(file)[0] + ".py" # Change .pyc for .py if file.endswith(self.PACKAGE_PATH_SUFFIX): file = os.path.dirname(file) # Track dir for packages return file
TRACK_IMPORTER = TrackImporter()