From 2837c1dc27dac958ffa37d82bc34a56b8860fbc9 Mon Sep 17 00:00:00 2001
From: Xavier Morel <xmo@openerp.com>
Date: Wed, 25 Sep 2013 16:52:05 +0200
Subject: [PATCH] [ADD] composition function utility

bzr revid: xmo@openerp.com-20130925145205-vumu9cgr5kob0900
---
 openerp/tests/__init__.py  |  2 ++
 openerp/tests/test_func.py | 22 ++++++++++++++++++++++
 openerp/tools/func.py      | 15 +++++++++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 openerp/tests/test_func.py

diff --git a/openerp/tests/__init__.py b/openerp/tests/__init__.py
index 0e86effe8f0..aa38f7831e9 100644
--- a/openerp/tests/__init__.py
+++ b/openerp/tests/__init__.py
@@ -22,6 +22,7 @@ import test_translate
 import test_uninstall
 import test_view_validation
 import test_qweb
+import test_func
 # This need a change in `oe run-tests` to only run fast_suite + checks by default.
 # import test_xmlrpc
 
@@ -43,6 +44,7 @@ checks = [
     test_osv,
     test_translate,
     test_qweb,
+    test_func,
 ]
  
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
diff --git a/openerp/tests/test_func.py b/openerp/tests/test_func.py
new file mode 100644
index 00000000000..7bb2e8fdf07
--- /dev/null
+++ b/openerp/tests/test_func.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+import functools
+import unittest2
+
+from ..tools.func import compose
+
+class TestCompose(unittest2.TestCase):
+    def test_basic(self):
+        str_add = compose(str, lambda a, b: a + b)
+        self.assertEqual(
+            str_add(1, 2),
+            "3")
+
+    def test_decorator(self):
+        """ ensure compose() can be partially applied as a decorator
+        """
+        @functools.partial(compose, unicode)
+        def mul(a, b):
+            return a * b
+
+        self.assertEqual(mul(5, 42), u"210")
+
diff --git a/openerp/tools/func.py b/openerp/tools/func.py
index 4728d971c69..ca8bba6bd49 100644
--- a/openerp/tools/func.py
+++ b/openerp/tools/func.py
@@ -57,4 +57,19 @@ def frame_codeinfo(fframe, back=0):
     except Exception:
         return "<unknown>", ''
 
+def compose(a, b):
+    """ Composes the callables ``a`` and ``b``. ``compose(a, b)(*args)`` is
+    equivalent to ``a(b(*args))``.
+
+    Can be used as a decorator by partially applying ``a``::
+
+         @partial(compose, a)
+         def b():
+            ...
+    """
+    @wraps(b)
+    def wrapper(*args, **kwargs):
+        return a(b(*args, **kwargs))
+    return wrapper
+
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: