Support reading configuration variables from devscripts configuration

files. (LP: #681693)

debian/changelog

@@ -1,9 +1,11 @@
 ubuntu-dev-tools (0.109) UNRELEASED; urgency=low
 
   * Convert debian/copyright to DEP5, make sure all scripts are listed
-   (LP: #692003)
+    (LP: #692003)
+  * Support reading configuration variables from devscripts configuration
+    files. (LP: #681693)
 
- -- Stefano Rivera <stefanor@ubuntu.com>  Sun, 19 Dec 2010 02:26:12 +0200
+ -- Stefano Rivera <stefanor@ubuntu.com>  Sun, 19 Dec 2010 20:41:06 +0200
 
 ubuntu-dev-tools (0.108) experimental; urgency=low
 

ubuntutools/common.py

@@ -32,3 +32,13 @@ import sys
 if os.environ.has_key('https_proxy'):
     print >> sys.stderr, "Ignoring https_proxy (no support in urllib/urllib2; see LP #122551)"
     del os.environ['https_proxy']
+
+
+def memoize_noargs(func):
+    "Simple memoization wrapper, for functions without arguments"
+    func.cache = None
+    def wrapper():
+        if func.cache is None:
+            func.cache = func()
+        return func.cache
+    return wrapper

ubuntutools/config.py

@@ -0,0 +1,61 @@
+# config.py - Common configuration file and environment variable handling for
+#             the ubuntu-dev-tools package.
+#
+# Copyright (C) 2010 Stefano Rivera <stefanor@ubuntu.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# See file /usr/share/common-licenses/GPL-2 for more details.
+#
+
+import os
+import os.path
+import re
+import sys
+
+from ubuntutools.common import memoize_noargs
+
+@memoize_noargs
+def get_devscripts_config():
+    """Read the devscripts configuration files, and return the values as a
+    dictionary
+    """
+    config = {}
+    var_re = re.compile(r'^\s*([A-Z_]+?)=(.+)$')
+    for fn in ('/etc/devscripts.conf', '~/.devscripts'):
+        f = open(os.path.expanduser(fn), 'r')
+        for line in f:
+            m = var_re.match(line)
+            if m:
+                config[m.group(1)] = m.group(2)
+        f.close()
+    return config
+
+def get_value(key, default=None, prefix=None, compat_keys=[]):
+    """Retrieve a value from the environment or configuration files.
+    keys are prefixed with the script name + _, or prefix.
+    Historical variable names can be supplied via compat_keys, no prefix is
+    applied to them.
+    """
+    if prefix is None:
+        prefix = sys.argv[0].upper().replace('-', '_') + '_'
+
+    keys = [prefix + key, 'UBUNTUTOOLS_' + key] + compat_keys
+
+    value = default
+    for store in (os.environ, get_devscripts_config()):
+        for k in keys:
+            if k in store:
+                value = store[k]
+                if value in ('yes', 'no'):
+                    value = value == 'yes'
+                return value
+    return value