[gentoo-commits] proj/portage:master commit in: pym/portage/util/futures/

[Brian Dolbec]

commit:     1b23a4134f0919e9541e7544213321efc51cac81
Author:     Brian Dolbec <dolsen <AT> gentoo <DOT> org>
AuthorDate: Mon Apr 25 01:09:54 2016 +0000
Commit:     Brian Dolbec <dolsen <AT> gentoo <DOT> org>
CommitDate: Mon Apr 25 15:28:53 2016 +0000
URL:        https://gitweb.gentoo.org/proj/portage.git/commit/?id=1b23a413

portage: Create a new extended futures class which adds standard data type access

This new class adds standard get, set functions along with optional defaults.
It also adds the capability to ignore InvalidStateErrors when trying to set the reslt more 
than once.

 pym/portage/util/futures/extendedfutures.py | 73 +++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/pym/portage/util/futures/extendedfutures.py b/pym/portage/util/futures/extendedfutures.py
new file mode 100644
index 0000000..af384c7
--- /dev/null
+++ b/pym/portage/util/futures/extendedfutures.py
@@ -0,0 +1,73 @@
+# Copyright 2016 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+#
+# This module provides an extended subset of the asyncio.futures.Futures
+# interface.
+
+from __future__ import unicode_literals
+
+__all__ = (
+	'CancelledError',
+	'ExtendedFuture',
+	'InvalidStateError',
+)
+
+from portage.util.futures.futures import (Future, InvalidStateError,
+	CancelledError)
+
+# Create our one time settable unset constant
+UNSET_CONST = Future()
+UNSET_CONST.set_result(object())
+
+
+class ExtendedFuture(Future):
+	'''Extended Future class adding convienince get and set operations with
+	default result capabilities for unset result().  It also adds pass
+	capability for duplicate set_result() calls.
+	'''
+
+	def __init__(self, default_result=UNSET_CONST.result()):
+		'''Class init
+
+		@param default_result: Optional data type/value to return in the event
+		                       of a result() call when result has not yet been
+		                       set.
+		'''
+		self.default_result = default_result
+		super(ExtendedFuture, self).__init__()
+		self.set = self.set_result
+
+	def set_result(self, data, ignore_InvalidState=False):
+		'''Set the Future's result to the data, optionally don't raise
+		an error for 'InvalidStateError' errors
+
+		@param ignore_exception: Boolean
+		'''
+		if ignore_InvalidState:
+			try:
+				super(ExtendedFuture, self).set_result(data)
+			except InvalidStateError:
+				pass
+		else:
+			super(ExtendedFuture, self).set_result(data)
+
+	def get(self, default=UNSET_CONST.result()):
+		'''Convienience function to wrap result() but adds an optional
+		default value to return rather than raise an InvalidStateError
+
+		@param default: Optional override for the classwide default_result
+		@returns: the result data or the default value, raisies an exception
+		          if result is unset and no default is defined.
+		'''
+		if default is not UNSET_CONST.result():
+			pass
+		elif self.default_result is not UNSET_CONST.result():
+			default = self.default_result
+		if default is not UNSET_CONST.result():
+			try:
+				data = super(ExtendedFuture, self).result()
+			except InvalidStateError:
+				data = default
+		else:
+			data = super(ExtendedFuture, self).result()
+		return data