diff options
Diffstat (limited to 'pym/portage_util.py')
| -rw-r--r-- | pym/portage_util.py | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/pym/portage_util.py b/pym/portage_util.py index 46a7d1052..6fd76090c 100644 --- a/pym/portage_util.py +++ b/pym/portage_util.py @@ -710,3 +710,30 @@ def ensure_dirs(dir_path, *args, **kwargs): raise perms_modified = apply_permissions(dir_path, *args, **kwargs) return created_dir or perms_modified + +class LazyItemsDict(dict): + """A mapping object that behaves like a standard dict except that it allows + for lazy initialization of values via callable objects. Lazy items can be + overwritten and deleted just as normal items.""" + def __init__(self): + dict.__init__(self) + self.lazy_items = {} + def addLazyItem(self, item_key, value_callable): + """Add a lazy item for the given key. When the item is requested, + value_callable will be called with no arguments.""" + self.lazy_items[item_key] = value_callable + # make it show up in self.keys(), etc... + dict.__setitem__(self, item_key, None) + def __getitem__(self, item_key): + if item_key in self.lazy_items: + return self.lazy_items[item_key]() + else: + return dict.__getitem__(self, item_key) + def __setitem__(self, item_key, value): + if item_key in self.lazy_items: + del self.lazy_items[item_key] + dict.__setitem__(self, item_key, value) + def __delitem__(self, item_key): + if item_key in self.lazy_items: + del self.lazy_items[item_key] + dict.__delitem__(self, item_key) |