depgraph.display(): handle reverse for --tree

This factors --tree logic out of the calling code, and allows
optimization of _show_merge_list to use reference comparison instead
of == comparison. Also, deprecate the unused depgraph.altlist()
"reversed" parameter, due to builtin name collision.

4 files changed, 21 insertions, 22 deletions

diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index 4e8b223fb..94d3d3f52 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -1827,11 +1827,7 @@ class Scheduler(PollScheduler):
 			return False
 
 		if success and self._show_list():
-			mylist = mydepgraph.altlist()
-			if mylist:
-				if "--tree" in self.myopts:
-					mylist = tuple(reversed(mylist))
-				mydepgraph.display(mylist, favorites=self._favorites)
+			mydepgraph.display(mydepgraph.altlist(), favorites=self._favorites)
 
 		if not success:
 			self._post_mod_echo_msgs.append(mydepgraph.display_problems)
diff --git a/pym/_emerge/actions.py b/pym/_emerge/actions.py
index 7b2cf54a5..d6e810084 100644
--- a/pym/_emerge/actions.py
+++ b/pym/_emerge/actions.py
@@ -336,7 +336,7 @@ def action_build(settings, trees, mtimedb,
 				return os.EX_OK
 			favorites = mtimedb["resume"]["favorites"]
 			retval = mydepgraph.display(
-				mydepgraph.altlist(reversed=tree),
+				mydepgraph.altlist(),
 				favorites=favorites)
 			mydepgraph.display_problems()
 			mergelist_shown = True
@@ -345,7 +345,7 @@ def action_build(settings, trees, mtimedb,
 			prompt="Would you like to resume merging these packages?"
 		else:
 			retval = mydepgraph.display(
-				mydepgraph.altlist(reversed=("--tree" in myopts)),
+				mydepgraph.altlist(),
 				favorites=favorites)
 			mydepgraph.display_problems()
 			mergelist_shown = True
@@ -404,7 +404,7 @@ def action_build(settings, trees, mtimedb,
 				return os.EX_OK
 			favorites = mtimedb["resume"]["favorites"]
 			retval = mydepgraph.display(
-				mydepgraph.altlist(reversed=tree),
+				mydepgraph.altlist(),
 				favorites=favorites)
 			mydepgraph.display_problems()
 			mergelist_shown = True
@@ -412,7 +412,7 @@ def action_build(settings, trees, mtimedb,
 				return retval
 		else:
 			retval = mydepgraph.display(
-				mydepgraph.altlist(reversed=("--tree" in myopts)),
+				mydepgraph.altlist(),
 				favorites=favorites)
 			mydepgraph.display_problems()
 			mergelist_shown = True
diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index 9c0a966c5..3e29508c7 100644
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -9,6 +9,7 @@ import logging
 import stat
 import sys
 import textwrap
+import warnings
 from collections import deque
 from itertools import chain
 
@@ -5694,7 +5695,12 @@ class depgraph(object):
 
 		mygraph.order.sort(key=cmp_sort_key(cmp_merge_preference))
 
-	def altlist(self, reversed=False):
+	def altlist(self, reversed=DeprecationWarning):
+
+		if reversed is not DeprecationWarning:
+			warnings.warn("The reversed parameter of "
+				"_emerge.depgraph.depgraph.altlist() is deprecated",
+				DeprecationWarning, stacklevel=2)
 
 		while self._dynamic_config._serialized_tasks_cache is None:
 			self._resolve_conflicts()
@@ -5705,8 +5711,8 @@ class depgraph(object):
 				pass
 
 		retlist = self._dynamic_config._serialized_tasks_cache
-		if reversed:
-			# TODO: deprecate the "reversed" parameter (builtin name collision)
+		if reversed is not DeprecationWarning and reversed:
+			# TODO: remove the "reversed" parameter (builtin name collision)
 			retlist = list(retlist)
 			retlist.reverse()
 			retlist = tuple(retlist)
@@ -6647,14 +6653,8 @@ class depgraph(object):
 	def _show_merge_list(self):
 		if self._dynamic_config._serialized_tasks_cache is not None and \
 			not (self._dynamic_config._displayed_list is not None and \
-			(self._dynamic_config._displayed_list is self._dynamic_config._serialized_tasks_cache or \
-			self._dynamic_config._displayed_list == self._dynamic_config._serialized_tasks_cache or \
-			self._dynamic_config._displayed_list == \
-				list(reversed(self._dynamic_config._serialized_tasks_cache)))):
-			display_list = self._dynamic_config._serialized_tasks_cache
-			if "--tree" in self._frozen_config.myopts:
-				display_list = tuple(reversed(display_list))
-			self.display(display_list)
+			self._dynamic_config._displayed_list is self._dynamic_config._serialized_tasks_cache):
+			self.display(self._dynamic_config._serialized_tasks_cache)
 
 	def _show_unsatisfied_blockers(self, blockers):
 		self._show_merge_list()
@@ -6749,6 +6749,10 @@ class depgraph(object):
 		# redundantly displaying this exact same merge list
 		# again via _show_merge_list().
 		self._dynamic_config._displayed_list = mylist
+
+		if "--tree" in self._frozen_config.myopts:
+			mylist = tuple(reversed(mylist))
+
 		display = Display()
 
 		return display(self, mylist, favorites, verbosity)
diff --git a/pym/_emerge/resolver/circular_dependency.py b/pym/_emerge/resolver/circular_dependency.py
index 6380b22c7..b7106714a 100644
--- a/pym/_emerge/resolver/circular_dependency.py
+++ b/pym/_emerge/resolver/circular_dependency.py
@@ -62,8 +62,7 @@ class circular_dependency_handler(object):
 				node = nodes[0]
 			display_order.append(node)
 			tempgraph.remove(node)
-		display_order.reverse()
-		return display_order
+		return tuple(display_order)
 
 	def _prepare_circular_dep_message(self):
 		"""