fix issue #149: operated on ScalarFloat cannot be dumped.0.15.32

Thanks for reporting

I "fixed" this by making the operators return a normal (bare) float, as the preservation is
mostly there for round-trips without operations.

Contrary to ScalarInt you cannot as easily preserve the style, and that needs a lot more testing,
and probably much smarter code (i.e. 1.23e4 *= 10 should probably give 1.23e5 and not 12.3e4).

*If this change makes things work again without your explicit convert to bare float, please
**Close** this issue.*

7 files changed, 32 insertions, 4 deletions

diff --git a/CHANGES b/CHANGES
index cd32f51..ff8f432 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,8 @@
+[0, 15, 32]: 2017-08-21
+  - allow setting ``yaml.default_flow_style = None`` (default: ``False``) for
+    for ``typ='rt'``.
+  - fix for issue 149: multiplications on ``ScalarFloat`` now return ``float``
+
 [0, 15, 31]: 2017-08-15
   - fix Comment dumping
 
diff --git a/README.rst b/README.rst
index a4ed52f..7cd8333 100644
--- a/README.rst
+++ b/README.rst
@@ -35,6 +35,11 @@ ChangeLog
 
 .. should insert NEXT: at the beginning of line for next key
 
+0.15.32 (2017-08-21):
+  - allow setting ``yaml.default_flow_style = None`` (default: ``False``) for
+    for ``typ='rt'``.
+  - fix for issue 149: multiplications on ``ScalarFloat`` now return ``float``
+
 0.15.31 (2017-08-15):
   - fix Comment dumping
 
diff --git a/__init__.py b/__init__.py
index 7f40acf..a90d9d2 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, 31),
-    __version__='0.15.31',
+    version_info=(0, 15, 32),
+    __version__='0.15.32',
     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/_test/test_api_change.py b/_test/test_api_change.py
index 4066603..c0f492c 100644
--- a/_test/test_api_change.py
+++ b/_test/test_api_change.py
@@ -126,6 +126,7 @@ class TestDuplSet:
             ? a
             """))
 
+
 class TestDumpLoadUnicode:
     # test triggered by SamH on stackoverflow (https://stackoverflow.com/q/45281596/1307905)
     # and answer by randomir (https://stackoverflow.com/a/45281922/1307905)
@@ -152,7 +153,7 @@ class TestFlowStyle:
         yaml.default_flow_style = None
         data = yaml.map()
         data['b'] = 1
-        data['a'] = [[1, 2],[3, 4]]
+        data['a'] = [[1, 2], [3, 4]]
         yaml.dump(data, sys.stdout)
         out, err = capsys.readouterr()
         assert out == "b: 1\na:\n- [1, 2]\n- [3, 4]\n"
diff --git a/_test/test_float.py b/_test/test_float.py
index 498c271..f9d060d 100644
--- a/_test/test_float.py
+++ b/_test/test_float.py
@@ -141,3 +141,14 @@ class TestFloat:
             ---
             - 1e6
             """)
+
+
+class TestCalculations(object):
+    def test_mul_00(self):
+        # issue 149 reported by jan.brezina@tul.cz
+        d = round_trip_load("""\
+        - 0.1
+        """)
+        d[0] *= -1
+        x = round_trip_dump(d)
+        assert x == '- -0.1\n'
diff --git a/representer.py b/representer.py
index 2279897..70746bc 100644
--- a/representer.py
+++ b/representer.py
@@ -653,7 +653,7 @@ class RoundTripRepresenter(SafeRepresenter):
     def __init__(self, default_style=None, default_flow_style=None, dumper=None):
         # type: (Any, Any, Any) -> None
         if not hasattr(dumper, 'typ') and default_flow_style is None:
-             default_flow_style = False
+            default_flow_style = False
         SafeRepresenter.__init__(self, default_style=default_style,
                                  default_flow_style=default_flow_style,
                                  dumper=dumper)
diff --git a/scalarfloat.py b/scalarfloat.py
index 7f7d26d..fca8be2 100644
--- a/scalarfloat.py
+++ b/scalarfloat.py
@@ -35,6 +35,7 @@ class ScalarFloat(float):
 
     def __iadd__(self, a):  # type: ignore
         # type: (Any) -> Any
+        return float(self) + a
         x = type(self)(self + a)
         x._width = self._width  # type: ignore
         x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
@@ -42,6 +43,7 @@ class ScalarFloat(float):
 
     def __ifloordiv__(self, a):  # type: ignore
         # type: (Any) -> Any
+        return float(self) // a
         x = type(self)(self // a)
         x._width = self._width  # type: ignore
         x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
@@ -49,13 +51,16 @@ class ScalarFloat(float):
 
     def __imul__(self, a):  # type: ignore
         # type: (Any) -> Any
+        return float(self) * a
         x = type(self)(self * a)
         x._width = self._width  # type: ignore
         x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._prec = self._prec   # check for others
         return x
 
     def __ipow__(self, a):  # type: ignore
         # type: (Any) -> Any
+        return float(self) ** a
         x = type(self)(self ** a)
         x._width = self._width  # type: ignore
         x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
@@ -63,6 +68,7 @@ class ScalarFloat(float):
 
     def __isub__(self, a):  # type: ignore
         # type: (Any) -> Any
+        return float(self) - a
         x = type(self)(self - a)
         x._width = self._width  # type: ignore
         x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA