matthewstory · March 20, 2014 04:47 · Mar 20, 2014
diff --git a/unicodify.py b/unicodify.py
@@ -0,0 +1,45 @@
+'''Decorators to convert all arguments passed to a function or method to
+   unicode or str, including default arguments'''
+import sys
+import functools
+import inspect
+
+def _convert_arg(arg, from_, conv, enc):
+    '''Safely convert unicode to string or string to unicode'''
+    return getattr(arg, conv)(encoding=enc) if isinstance(arg, from_) else arg
+
+def _wrap_convert(from_type, fn, encoding=None):
+    '''Decorate a function converting all str arguments to unicode or
+       vice-versa'''
+    conv = 'decode' if from_type is str else 'encode'
+    encoding = encoding or sys.getdefaultencoding()
+
+    # override string defaults using partial
+    aspec, dflts = inspect.getargspec(fn), {}
+    if aspec.defaults:
+        for k,v in zip(aspec.args[-len(aspec.defaults):],aspec.defaults):
+            dflts[k] = _convert_arg(v, from_type, conv, encoding)
+        fn = functools.partial(fn, **dflts)
+
+    @functools.wraps(fn.func if isinstance(fn, functools.partial) else fn)
+    def converted(*args, **kwargs):
+        args = [_convert_arg(a, from_type, conv, encoding) for a in args]
+        for k,v in kwargs.iteritems():
+            kwargs[k] = _convert_arg(v, from_type, conv, encoding)
+        return fn(*args, **kwargs)
+
+    return converted
+
+def unicodify(fn=None, encoding=None):
+    '''Convert all str arguments to unicode'''
+    if fn is None:
+        return functools.partial(unicodify, encoding=encoding)
+    return _wrap_convert(str, fn, encoding=encoding)
+
+def stringify(fn=None, encoding=None):
+    '''Convert all unicode arguments to str'''
+    if fn is None:
+        return functools.partial(stringify, encoding=encoding)
+    return _wrap_convert(unicode, fn, encoding=encoding)
+
+__all__ = ['unicodify', 'stringify']