Rev 6350: Allow config option default value to be a python callable in file:///home/vila/src/bzr/bugs/832064-default-value-callable/

[Vincent Ladeuil]

At file:///home/vila/src/bzr/bugs/832064-default-value-callable/

------------------------------------------------------------
revno: 6350
revision-id: v.ladeuil+lp at free.fr-20111209161532-ktm62xw0euieo7wj
parent: pqm at pqm.ubuntu.com-20111206163008-eoqz60dpbysebble
fixes bug: https://launchpad.net/bugs/832064
committer: Vincent Ladeuil <v.ladeuil+lp at free.fr>
branch nick: 832064-default-value-callable
timestamp: Fri 2011-12-09 17:15:32 +0100
message:
  Allow config option default value to be a python callable
-------------- next part --------------
=== modified file 'bzrlib/config.py'
--- a/bzrlib/config.py	2011-11-29 14:59:18 +0000
+++ b/bzrlib/config.py	2011-12-09 16:15:32 +0000
@@ -2331,8 +2331,10 @@
 
         :param default: the default value to use when none exist in the config
             stores. This is either a string that ``from_unicode`` will convert
-            into the proper type or a python object that can be stringified (so
-            only the empty list is supported for example).
+            into the proper type, a callable returning a unicode string so that
+            ``from_unicode`` can be used on the return value, or a python
+            object that can be stringified (so only the empty list is supported
+            for example).
 
         :param default_from_env: A list of environment variables which can
            provide a default value. 'default' will be used only if none of the
@@ -2367,6 +2369,8 @@
         elif isinstance(default, (str, unicode, bool, int, float)):
             # Rely on python to convert strings, booleans and integers
             self.default = u'%s' % (default,)
+        elif callable(default):
+            self.default = default
         else:
             # other python objects are not expected
             raise AssertionError('%r is not supported as a default value'
@@ -2407,7 +2411,13 @@
                 continue
         if value is None:
             # Otherwise, fallback to the value defined at registration
-            value = self.default
+            if callable(self.default):
+                value = self.default()
+                if not isinstance(value, unicode):
+                    raise AssertionError(
+                    'Callable default values should be unicode')
+            else:
+                value = self.default
         return value
 
     def get_help_text(self, additional_see_also=None, plain=True):

=== modified file 'bzrlib/tests/test_config.py'
--- a/bzrlib/tests/test_config.py	2011-11-22 11:50:36 +0000
+++ b/bzrlib/tests/test_config.py	2011-12-09 16:15:32 +0000
@@ -2275,6 +2275,12 @@
         opt = config.Option('foo', default='bar')
         self.assertEquals('bar', opt.get_default())
 
+    def test_callable_default_value(self):
+        def bar_as_unicode():
+            return u'bar'
+        opt = config.Option('foo', default=bar_as_unicode)
+        self.assertEquals('bar', opt.get_default())
+
     def test_default_value_from_env(self):
         opt = config.Option('foo', default='bar', default_from_env=['FOO'])
         self.overrideEnv('FOO', 'quux')
@@ -2296,6 +2302,12 @@
         self.assertRaises(AssertionError, config.Option, 'foo',
                           default=object())
 
+    def test_not_supported_callable_default_value_not_unicode(self):
+        def bar_not_unicode():
+            return 'bar'
+        opt = config.Option('foo', default=bar_not_unicode)
+        self.assertRaises(AssertionError, opt.get_default)
+
 
 class TestOptionConverterMixin(object):
 
@@ -2363,6 +2375,7 @@
         opt = self.get_option()
         self.assertConverted(16, opt, u'16')
 
+
 class TestOptionWithListConverter(tests.TestCase, TestOptionConverterMixin):
 
     def get_option(self):