Created---yes---filter-in-default-filters-.patch

From c693dfaa46218537fb66e6e30638ee81f5374fac Mon Sep 17 00:00:00 2001
From: Ben Spaulding <[email protected]>
Date: Fri, 20 Mar 2009 00:22:21 -0500
Subject: [PATCH] Created ``yes`` filter in default filters.
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit

I cannot count the times that I wanted to output a string if
the value was true, but output nothing otherwise. This leads
to countless bits like so::

    {% block body_class %}{{ block.super }}{% if val %} my_class{% endif %}{% endblock %}

Using this filter that redundant sort of line becomes::

    {% block body_class %}{{ block.super }}{{ val|yes:" my_class" }}{% endblock %}

It saves some typing (though not a lot) and makes it a little
more readable, IMHO.

This is just a idea. I am not sure how many people would use
it — maybe a lot, maybe very few.
---
 django/template/defaultfilters.py             |   21 +++++++++++++++++++++
 docs/ref/templates/builtins.txt               |   16 ++++++++++++++++
 tests/regressiontests/defaultfilters/tests.py |   15 +++++++++++++++
 3 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/django/template/defaultfilters.py b/django/template/defaultfilters.py
index ff8d418..f36717c 100644
--- a/django/template/defaultfilters.py
+++ b/django/template/defaultfilters.py
@@ -732,6 +732,26 @@ def divisibleby(value, arg):
     return int(value) % int(arg) == 0
 divisibleby.is_safe = False
 
+def yes(value, arg=None):
+    """
+    Given a string, returns that string if the value is true. Otherwise,
+    returns an empty string.
+
+    ==========  =============  ===============
+    Value       Argument       Outputs
+    ==========  =============  ===============
+    ``True``    ``"yeah"``     ``yeah``
+    ``False``   ``"yeah"``     (empty string)
+    ``None``    ``"yeah"``     (empty string)
+    ==========  =============  ===============
+    """
+    if arg is None:
+        arg = ugettext('yes')
+    if value:
+        return arg
+    return u''
+yes.is_safe = False
+
 def yesno(value, arg=None):
     """
     Given a string mapping values for true, false and (optionally) None,
@@ -902,4 +922,5 @@ register.filter(urlize)
 register.filter(urlizetrunc)
 register.filter(wordcount)
 register.filter(wordwrap)
+register.filter(yes)
 register.filter(yesno)
diff --git a/docs/ref/templates/builtins.txt b/docs/ref/templates/builtins.txt
index 17e6e8b..64f341e 100644
--- a/docs/ref/templates/builtins.txt
+++ b/docs/ref/templates/builtins.txt
@@ -1609,6 +1609,22 @@ If ``value`` is ``Joel is a slug``, the output would be::
     is a
     slug
 
+.. templatefilter:: yes
+
+yes
+~~~
+
+Given a string, returns that string if the value is true. Otherwise,
+returns an empty string.
+
+==========  =============  ===============
+Value       Argument       Outputs
+==========  =============  ===============
+``True``    ``"yeah"``     ``yeah``
+``False``   ``"yeah"``     (empty string)
+``None``    ``"yeah"``     (empty string)
+==========  =============  ===============
+
 .. templatefilter:: yesno
 
 yesno
diff --git a/tests/regressiontests/defaultfilters/tests.py b/tests/regressiontests/defaultfilters/tests.py
index a97596f..b49d80e 100644
--- a/tests/regressiontests/defaultfilters/tests.py
+++ b/tests/regressiontests/defaultfilters/tests.py
@@ -419,6 +419,21 @@ True
 >>> divisibleby(4, 3)
 False
 
+>>> yes(True)
+u'yes'
+
+>>> yes(False)
+u''
+
+>>> yes(True, u'certainly')
+u'certainly'
+
+>>> yes(False, u'certainly')
+u''
+
+>>> yes(None)
+u''
+
 >>> yesno(True)
 u'yes'
 
-- 
1.6.0.2+GitX