c7a78642fd
- GUI interactive python prompt, useful in a variety of situations where
python -i or ipython don't work very well.
- Command history (requires a little help finding storage for this)
- Exception catching, allowing the user to inspect local variables
at any level within a stack trace (currently, this is done _without_
blocking the application)
91 lines
3.4 KiB
Python
91 lines
3.4 KiB
Python
# -*- coding: utf-8 -*-
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"""This module installs a wrapper around sys.excepthook which allows multiple
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new exception handlers to be registered.
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Optionally, the wrapper also stops exceptions from causing long-term storage
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of local stack frames. This has two major effects:
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- Unhandled exceptions will no longer cause memory leaks
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(If an exception occurs while a lot of data is present on the stack,
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such as when loading large files, the data would ordinarily be kept
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until the next exception occurs. We would rather release this memory
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as soon as possible.)
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- Some debuggers may have a hard time handling uncaught exceptions
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The module also provides a callback mechanism allowing others to respond
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to exceptions.
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"""
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import sys, time
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#from lib.Manager import logMsg
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import traceback
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#from log import *
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#logging = False
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callbacks = []
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clear_tracebacks = False
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def register(fn):
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"""
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Register a callable to be invoked when there is an unhandled exception.
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The callback will be passed the output of sys.exc_info(): (exception type, exception, traceback)
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Multiple callbacks will be invoked in the order they were registered.
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"""
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callbacks.append(fn)
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def unregister(fn):
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"""Unregister a previously registered callback."""
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callbacks.remove(fn)
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def setTracebackClearing(clear=True):
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"""
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Enable or disable traceback clearing.
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By default, clearing is disabled and Python will indefinitely store unhandled exception stack traces.
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This function is provided since Python's default behavior can cause unexpected retention of
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large memory-consuming objects.
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"""
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global clear_tracebacks
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clear_tracebacks = clear
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class ExceptionHandler:
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def __call__(self, *args):
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## call original exception handler first (prints exception)
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global original_excepthook, callbacks, clear_tracebacks
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print "=====", time.strftime("%Y.%m.%d %H:%m:%S", time.localtime(time.time())), "====="
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ret = original_excepthook(*args)
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for cb in callbacks:
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try:
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cb(*args)
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except:
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print " --------------------------------------------------------------"
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print " Error occurred during exception callback", cb
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print " --------------------------------------------------------------"
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traceback.print_exception(*sys.exc_info())
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## Clear long-term storage of last traceback to prevent memory-hogging.
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## (If an exception occurs while a lot of data is present on the stack,
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## such as when loading large files, the data would ordinarily be kept
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## until the next exception occurs. We would rather release this memory
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## as soon as possible.)
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if clear_tracebacks is True:
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sys.last_traceback = None
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def implements(self, interface=None):
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## this just makes it easy for us to detect whether an ExceptionHook is already installed.
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if interface is None:
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return ['ExceptionHandler']
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else:
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return interface == 'ExceptionHandler'
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## replace built-in excepthook only if this has not already been done
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if not (hasattr(sys.excepthook, 'implements') and sys.excepthook.implements('ExceptionHandler')):
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original_excepthook = sys.excepthook
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sys.excepthook = ExceptionHandler()
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