diff options
| -rw-r--r-- | pkg_resources/__init__.py | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py index 602549be..6aabd4c5 100644 --- a/pkg_resources/__init__.py +++ b/pkg_resources/__init__.py @@ -947,11 +947,17 @@ class WorkingSet(object): return needed - def subscribe(self, callback): - """Invoke `callback` for all distributions (including existing ones)""" + def subscribe(self, callback, existing=True): + """Invoke `callback` for all distributions + + If `existing=True` (default), + call on all existing ones, as well. + """ if callback in self.callbacks: return self.callbacks.append(callback) + if not existing: + return for dist in self: callback(dist) @@ -2967,10 +2973,14 @@ def _initialize_master_working_set(): run_script = working_set.run_script # backward compatibility run_main = run_script - # Activate all distributions already on sys.path, and ensure that - # all distributions added to the working set in the future (e.g. by - # calling ``require()``) will get activated as well. - add_activation_listener(lambda dist: dist.activate()) + # Activate all distributions already on sys.path with replace=False and + # ensure that all distributions added to the working set in the future + # (e.g. by calling ``require()``) will get activated as well, + # with higher priority (replace=True). + for dist in working_set: + dist.activate(replace=False) + del dist + add_activation_listener(lambda dist: dist.activate(replace=True), existing=False) working_set.entries=[] # match order list(map(working_set.add_entry, sys.path)) |