support the flush parameter of print_ (fixes #106)

4 files changed, 24 insertions, 2 deletions

diff --git a/CHANGES b/CHANGES
index e257d61..adef9ea 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,8 @@ This file lists the changes in each six version.
 Development version
 -------------------
 
+- Issue #106: Support the `flush` parameter to `six.print_`.
+
 - Pull request #48 and issue #15: Add the `python_2_unicode_compatible`
   decorator.
 
diff --git a/documentation/index.rst b/documentation/index.rst
index 627862a..1f27400 100644
--- a/documentation/index.rst
+++ b/documentation/index.rst
@@ -270,10 +270,11 @@ Python 2 and 3.
       :func:`exec` with them should be avoided.
 
 
-.. function:: print_(*args, *, file=sys.stdout, end="\\n", sep=" ")
+.. function:: print_(*args, *, file=sys.stdout, end="\\n", sep=" ", flush=False)
 
    Print *args* into *file*.  Each argument will be separated with *sep* and
-   *end* will be written to the file after the last argument is printed.
+   *end* will be written to the file after the last argument is printed.  If
+   *flush* is true, ``file.flush()`` will be called after all data is written.
 
    .. note::
 
diff --git a/six.py b/six.py
index b54590f..f121064 100644
--- a/six.py
+++ b/six.py
@@ -740,6 +740,14 @@ if print_ is None:
                 write(sep)
             write(arg)
         write(end)
+if sys.version_info[:2] < (3, 3):
+    _print = print_
+    def print_(*args, **kwargs):
+        fp = kwargs.get("file", sys.stdout)
+        flush = kwargs.pop("flush", False)
+        _print(*args, **kwargs)
+        if flush and fp is not None:
+            fp.flush()
 
 _add_doc(reraise, """Reraise an exception.""")
 
diff --git a/test_six.py b/test_six.py
index 3a3faff..76a8ccb 100644
--- a/test_six.py
+++ b/test_six.py
@@ -636,6 +636,17 @@ def test_print_():
     out = six.StringIO()
     six.print_(None, file=out)
     assert out.getvalue() == "None\n"
+    class FlushableStringIO(six.StringIO):
+        def __init__(self):
+            six.StringIO.__init__(self)
+            self.flushed = False
+        def flush(self):
+            self.flushed = True
+    out = FlushableStringIO()
+    six.print_("Hello", file=out)
+    assert not out.flushed
+    six.print_("Hello", file=out, flush=True)
+    assert out.flushed
 
 
 @py.test.mark.skipif("sys.version_info[:2] >= (2, 6)")