From patchwork Thu Jan 14 22:17:48 2016
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Subject: [1,of,2] extensions: add get contextmanager to avoid common pattern
From: Laurent Charignon <lcharignon@fb.com>
X-Patchwork-Id: 12776
Message-Id: <c1ba4521aea0906874fe.1452809868@lcharignon-mbp.dhcp.thefacebook.com>
To: <mercurial-devel@selenic.com>
Date: Thu, 14 Jan 2016 14:17:48 -0800

# HG changeset patch
# User Laurent Charignon <lcharignon@fb.com>
# Date 1452809804 28800
#      Thu Jan 14 14:16:44 2016 -0800
# Node ID c1ba4521aea0906874fe7de5bee156d5070c0e56
# Parent  e6e34c4e391668c5d8af8f98c004a27c77b1e2fa
extensions: add get contextmanager to avoid common pattern

Before this patch, people were sometimes using the following pattern:

try:
    m = extensions.find(name)
    ...
except KeyError:
    pass

This patch simplifies the pattern with context managers as follow:

with extensions.get(name) as m:
    ...

diff --git a/mercurial/extensions.py b/mercurial/extensions.py
--- a/mercurial/extensions.py
+++ b/mercurial/extensions.py
@@ -7,6 +7,7 @@
 
 from __future__ import absolute_import
 
+from contextlib import contextmanager
 import imp
 import os
 
@@ -41,6 +42,13 @@ def extensions(ui=None):
         if module and enabled(name):
             yield name, module
 
+@contextmanager
+def get(name):
+    try:
+        yield find(name)
+    except KeyError:
+        pass
+
 def find(name):
     '''return module with given extension name'''
     mod = None