michael@0: from __future__ import with_statement
michael@0: 
michael@0: import sys
michael@0: 
michael@0: __all__ = ['nested', 'catch_warnings', 'examine_warnings']
michael@0: 
michael@0: 
michael@0: try:
michael@0:     from contextlib import nested
michael@0: except ImportError:
michael@0:     from contextlib import contextmanager
michael@0:     @contextmanager
michael@0:     def nested(*managers):
michael@0:         exits = []
michael@0:         vars = []
michael@0:         exc = (None, None, None)
michael@0:         try:
michael@0:             for mgr in managers:
michael@0:                 exit = mgr.__exit__
michael@0:                 enter = mgr.__enter__
michael@0:                 vars.append(enter())
michael@0:                 exits.append(exit)
michael@0:             yield vars
michael@0:         except:
michael@0:             exc = sys.exc_info()
michael@0:         finally:
michael@0:             while exits:
michael@0:                 exit = exits.pop()
michael@0:                 try:
michael@0:                     if exit(*exc):
michael@0:                         exc = (None, None, None)
michael@0:                 except:
michael@0:                     exc = sys.exc_info()
michael@0:             if exc != (None, None, None):
michael@0:                 raise exc[1]
michael@0: 
michael@0: # copied from Python 2.6
michael@0: try:
michael@0:     from warnings import catch_warnings
michael@0: except ImportError:
michael@0:     class catch_warnings(object):
michael@0:         def __init__(self, record=False, module=None):
michael@0:             self._record = record
michael@0:             self._module = sys.modules['warnings']
michael@0:             self._entered = False
michael@0: 
michael@0:         def __repr__(self):
michael@0:             args = []
michael@0:             if self._record:
michael@0:                 args.append("record=True")
michael@0:             name = type(self).__name__
michael@0:             return "%s(%s)" % (name, ", ".join(args))
michael@0: 
michael@0:         def __enter__(self):
michael@0:             if self._entered:
michael@0:                 raise RuntimeError("Cannot enter %r twice" % self)
michael@0:             self._entered = True
michael@0:             self._filters = self._module.filters
michael@0:             self._module.filters = self._filters[:]
michael@0:             self._showwarning = self._module.showwarning
michael@0:             if self._record:
michael@0:                 log = []
michael@0:                 def showwarning(*args, **kwargs):
michael@0:                     log.append(WarningMessage(*args, **kwargs))
michael@0:                 self._module.showwarning = showwarning
michael@0:                 return log
michael@0:             else:
michael@0:                 return None
michael@0: 
michael@0:         def __exit__(self, *exc_info):
michael@0:             if not self._entered:
michael@0:                 raise RuntimeError("Cannot exit %r without entering first" % self)
michael@0:             self._module.filters = self._filters
michael@0:             self._module.showwarning = self._showwarning
michael@0: 
michael@0:     class WarningMessage(object):
michael@0:         _WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
michael@0:                             "line")
michael@0:         def __init__(self, message, category, filename, lineno, file=None,
michael@0:                         line=None):
michael@0:             local_values = locals()
michael@0:             for attr in self._WARNING_DETAILS:
michael@0:                 setattr(self, attr, local_values[attr])
michael@0:             self._category_name = None
michael@0:             if category.__name__:
michael@0:                 self._category_name = category.__name__
michael@0: 
michael@0: 
michael@0: def examine_warnings(func):
michael@0:     def wrapper():
michael@0:         with catch_warnings(record=True) as ws:
michael@0:             func(ws)
michael@0:     return wrapper