Refine FAQ entry for catching stdout
diff --git a/Doc/faq/extending.rst b/Doc/faq/extending.rst
index 676890e..7c684a0 100644
--- a/Doc/faq/extending.rst
+++ b/Doc/faq/extending.rst
@@ -142,21 +142,30 @@
just allow the standard traceback mechanism to work. Then, the output will go
wherever your ``write()`` method sends it.
-The easiest way to do this is to use the StringIO class in the standard library.
+The easiest way to do this is to use the :class:`io.StringIO` class::
-Sample code and use for catching stdout:
+ >>> import io, sys
+ >>> sys.stdout = io.StringIO()
+ >>> print('foo')
+ >>> print('hello world!')
+ >>> sys.stderr.write(sys.stdout.getvalue())
+ foo
+ hello world!
- >>> class StdoutCatcher:
+A custom object to do the same would look like this::
+
+ >>> import io, sys
+ >>> class StdoutCatcher(io.TextIOBase):
... def __init__(self):
- ... self.data = ''
+ ... self.data = []
... def write(self, stuff):
- ... self.data = self.data + stuff
+ ... self.data.append(stuff)
...
>>> import sys
>>> sys.stdout = StdoutCatcher()
>>> print('foo')
>>> print('hello world!')
- >>> sys.stderr.write(sys.stdout.data)
+ >>> sys.stderr.write(''.join(sys.stdout.data))
foo
hello world!