add BooleanAction for argparse

This action allows to set a boolean flag
via --foo=BAR, where BAR is y/n,true/false etc.

2 files changed, 30 insertions, 0 deletions

diff --git a/alot/utils/__init__.py b/alot/utils/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/alot/utils/__init__.py
diff --git a/alot/utils/booleanaction.py b/alot/utils/booleanaction.py
new file mode 100644
index 00000000..37fd804f
--- /dev/null
+++ b/alot/utils/booleanaction.py
@@ -0,0 +1,30 @@
+"""
+This defines the ConfigureAction for argparse found here:
+http://code.google.com/p/argparse/issues/detail?id=2#c6
+
+We use it to set booelan arguments for command parameters
+to False using a `--no-` prefix.
+"""
+import argparse
+import re
+
+
+TRUEISH = ['1', 't', 'true', 'yes', 'on']
+FALSISH = ['0', 'f', 'false', 'no', 'off']
+
+def boolean(string):
+    string = string.lower()
+    if string in FALSISH:
+        return False
+    elif string in TRUEISH:
+        return True
+    else:
+        raise ValueError()
+
+
+class BooleanAction(argparse.Action):
+    def __init__(self, *args, **kwargs):
+        kwargs['type'] = boolean
+        kwargs['choices'] = TRUEISH + FALSISH
+        #%kwargs['metavar'] = 'BOOL'
+        argparse.Action.__init__(self, *args, **kwargs)