element.py: Cache ElementProxies
This allows plugins to keep making statements such as `element in dependencies`
or `elementA is elementB`, which was currently broken due to creating proxies
on demand.
diff --git a/src/buildstream/element.py b/src/buildstream/element.py
index 3316d8a..46d5ef4 100644
--- a/src/buildstream/element.py
+++ b/src/buildstream/element.py
@@ -1,5 +1,5 @@
#
-# Copyright (C) 2016-2018 Codethink Limited
+# Copyright (C) 2016-2020 Codethink Limited
# Copyright (C) 2017-2020 Bloomberg Finance LP
#
# This program is free software; you can redistribute it and/or
@@ -240,6 +240,8 @@
# Private instance properties
#
+ # Cache of proxies instantiated, indexed by the proxy owner
+ self.__proxies = {} # type: Dict[Element, ElementProxy]
# Direct runtime dependency Elements
self.__runtime_dependencies = [] # type: List[Element]
# Direct build dependency Elements
@@ -483,7 +485,7 @@
# methods.
#
for dep in element._dependencies(scope, recurse=recurse, visited=visited):
- yield cast("Element", ElementProxy(self, dep))
+ yield cast("Element", dep.__get_proxy(self))
def search(self, name: str) -> Optional["Element"]:
"""Search for a dependency by name
@@ -498,7 +500,7 @@
if search is self:
return self
elif search:
- return cast("Element", ElementProxy(self, search))
+ return cast("Element", search.__get_proxy(self))
return None
@@ -2319,6 +2321,29 @@
# Private Local Methods #
#############################################################
+ # __get_proxy()
+ #
+ # Obtain a proxy for this element for the specified `owner`.
+ #
+ # We cache the proxies for plugin convenience, this allows plugins
+ # compare proxies to other proxies returned to them, so they
+ # can run valid statements such as `proxy_a is `proxy_b` or
+ # `proxy_a in list_of_proxies`.
+ #
+ # Args:
+ # owner (Element): The owning element
+ #
+ # Returns:
+ # (ElementProxy): An ElementProxy to self, for owner.
+ #
+ def __get_proxy(self, owner: "Element") -> ElementProxy:
+ with suppress(KeyError):
+ return self.__proxies[owner]
+
+ proxy = ElementProxy(owner, self)
+ self.__proxies[owner] = proxy
+ return proxy
+
# __load_sources()
#
# Load the Source objects from the LoadElement
