allow None stream if transforming0.15.35

If YAML.dump() is passed a transform function, specifying None
will ignore the return value of that function.

4 files changed, 22 insertions, 5 deletions

diff --git a/CHANGES b/CHANGES
index 5b61f46..7cc5fd3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,10 @@
+[0, 15, 35]: 2017-12-03
+  - allow ``None`` as stream when specifying ``transform`` parameters to
+    ``YAML.dump()``.
+    This is useful if the transforming function doesn't return a meaningful value
+    (inspired by `StackOverflow <https://stackoverflow.com/q/47614862/1307905>`__ by
+    `rsaw <https://stackoverflow.com/users/406281/rsaw>`__).
+
 [0, 15, 34]: 2017-09-17
   - fix for issue 157: CDumper not dumping floats (reported by Jan Smitka)
 
diff --git a/README.rst b/README.rst
index f47e088..7da68db 100644
--- a/README.rst
+++ b/README.rst
@@ -33,7 +33,14 @@ when the status of the API is stable enough to make the transition.
 ChangeLog
 =========
 
-.. should insert NEXT: at the beginning of line for next key
+.. should insert NEXT: at the beginning of line for next key (with empty line)
+
+0.15.35 (2017-12-03):
+  - allow ``None`` as stream when specifying ``transform`` parameters to
+    ``YAML.dump()``.
+    This is useful if the transforming function doesn't return a meaningful value
+    (inspired by `StackOverflow <https://stackoverflow.com/q/47614862/1307905>`__ by
+    `rsaw <https://stackoverflow.com/users/406281/rsaw>`__).
 
 0.15.34 (2017-09-17):
   - fix for issue 157: CDumper not dumping floats (reported by Jan Smitka)
@@ -99,7 +106,7 @@ ChangeLog
   - fix for round_tripping singe excl. mark tags doubling (reported and fix by Jan Brezina)
 
 0.15.21 (2017-07-25):
-  - fix for writing unicode in new API, (reported on 
+  - fix for writing unicode in new API, (reported on
     `StackOverflow <https://stackoverflow.com/a/45281922/1307905>`__
 
 0.15.20 (2017-07-23):
diff --git a/__init__.py b/__init__.py
index 9da7f51..7b190f3 100644
--- a/__init__.py
+++ b/__init__.py
@@ -7,8 +7,8 @@ if False:  # MYPY
 
 _package_data = dict(
     full_package_name='ruamel.yaml',
-    version_info=(0, 15, 34),
-    __version__='0.15.34',
+    version_info=(0, 15, 35),
+    __version__='0.15.35',
     author='Anthon van der Neut',
     author_email='a.van.der.neut@ruamel.eu',
     description='ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order',  # NOQA
diff --git a/main.py b/main.py
index 1b5c2d0..e933210 100644
--- a/main.py
+++ b/main.py
@@ -399,7 +399,10 @@ class YAML(object):
             val = stream.getvalue()  # type: ignore
             if self.encoding:
                 val = val.decode(self.encoding)
-            fstream.write(transform(val))
+            if fstream is None:
+                transform(val)
+            else:
+                fstream.write(transform(val))
         return None
 
     def get_serializer_representer_emitter(self, stream, tlca):