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Speedup builtin_trap enter/exit by reducing object creation....
Speedup builtin_trap enter/exit by reducing object creation. Most of the work that was being done on *every* enter/exit cycle could be done statically only once, at object creation time. This trap is used on every single code execution, so we need it to be fast. In the long run we probably want to rethink this system altogether, but for now at least we want it fast.

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output_trap.py
107 lines | 2.6 KiB | text/x-python | PythonLexer
# encoding: utf-8
""" Trap stdout/stderr."""
__docformat__ = "restructuredtext en"
#-------------------------------------------------------------------------------
# Copyright (C) 2008 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-------------------------------------------------------------------------------
#-------------------------------------------------------------------------------
# Imports
#-------------------------------------------------------------------------------
import sys
from cStringIO import StringIO
class OutputTrap(object):
""" Object which can trap text sent to stdout and stderr.
"""
def __init__(self, out=None, err=None):
# Filelike objects to store stdout/stderr text.
if out is None:
self.out = StringIO()
else:
self.out = out
if err is None:
self.err = StringIO()
else:
self.err = err
# Boolean to check if the stdout/stderr hook is set.
self.out_set = False
self.err_set = False
@property
def out_text(self):
""" Return the text currently in the stdout buffer.
"""
return self.out.getvalue()
@property
def err_text(self):
""" Return the text currently in the stderr buffer.
"""
return self.err.getvalue()
def set(self):
""" Set the hooks.
"""
if sys.stdout is not self.out:
self._out_save = sys.stdout
sys.stdout = self.out
self.out_set = True
if sys.stderr is not self.err:
self._err_save = sys.stderr
sys.stderr = self.err
self.err_set = True
def unset(self):
""" Remove the hooks.
"""
if self.out_set:
sys.stdout = self._out_save
self.out_set = False
if self.err_set:
sys.stderr = self._err_save
self.err_set = False
def clear(self):
""" Clear out the buffers.
"""
self.out.reset()
self.out.truncate()
self.err.reset()
self.err.truncate()
def add_to_message(self, message):
""" Add the text from stdout and stderr to the message from the
interpreter to its listeners.
Parameters
----------
message : dict
"""
out_text = self.out_text
if out_text:
message['stdout'] = out_text
err_text = self.err_text
if err_text:
message['stderr'] = err_text