osh.error

1 # osh 2 # Copyright (C) 2005 Jack Orenstein <jao@geophile.com> 3 # 4 # This program is free software; you can redistribute it and/or modify 5 # it under the terms of the GNU General Public License as published by 6 # the Free Software Foundation; either version 2 of the License, or 7 # (at your option) any later version. 8 # 9 # This program is distributed in the hope that it will be useful, 10 # but WITHOUT ANY WARRANTY; without even the implied warranty of 11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 # GNU General Public License for more details. 13 # 14 # You should have received a copy of the GNU General Public License 15 # along with this program; if not, write to the Free Software 16 # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 18 """Controls handling of exceptions and stderr through the setting of handlers. 19 20 An C{exception_handler} is a function with these arguments: 21 - C{exception}: The exception being handled. In case of a remote exception, this exception object is a client-side reconstruction of the server-side exception. 22 - C{op}: A command of type C{Op}, or, in case of a remote exception, a command description, obtained by applying C{str()}. 23 - C{input}: Input to the command that raised the exception. 24 - C{host}: The host on which the exception occurred, or C{None} if local. 25 26 An C{error_handler} is a function with these arguments: 27 - C{line}: A line written to stderr. 28 - C{op}: A command of type C{Op}, or, in case of remote stderr output, a command description, obtained by applying C{str()}. 29 - C{input}: Input to the command that generated the stderr output. 30 - C{host}: The host on which the stderr output occurred, or C{None} if local. 31 """ 32 33 import sys 34 import new 35

36 -class Error(object):

37 38 _command_description = None 39 _input = None 40 _exception_args = None 41 _exception_type_name = None 42 _exception_message = None 43

44 - def __init__(self, command_description, input, exception):

45 self._command_description = command_description 46 self._input = input 47 self._exception_args = exception.args 48 self._exception_type_name = str(exception.__class__) 49 self._exception_message = str(exception)

50

51 - def __str__(self):

52 return ('Encountered %s during execution of %s on input %s: %s' % 53 (self._exception_type_name, 54 self._command_description, 55 self._input, 56 self._exception_message))

57

58 - def recreate_exception(self):

59 last_dot = self._exception_type_name.rfind('.') 60 assert last_dot > 0, self._exception_type_name 61 module_name = self._exception_type_name[:last_dot] 62 exec 'import %s' % module_name 63 klass = eval(self._exception_type_name) 64 return new.instance(klass, {'args': str(self)})

65

66 - def command_description(self):

67 return self._command_description

68

69 - def input(self):

70 return self._input

71 72 #---------------------------------------------------------------------- 73 74 # Exception and error handling 75 76 # Exception thrown by exception handler needs to terminate osh. 77 # Use ExceptionHandlerException to tunnel through except blocks. 78

79 -class ExceptionHandlerException(Exception):

80

81 - def __init__(self, cause):

82 Exception.__init__(self) 83 self.cause = cause

84

85 - def __str__(self):

86 return str(self.cause)

87 88 89 # exception_handler is a function with these arguments: 90 # - exception: The exception being handled. In case of a remote exception, this exception 91 # object is a client-side reconstruction of the server-side exception. 92 # - op: A command of type Op, or, in case of a remote exception, a command description, 93 # obtained by applying str(). 94 # - host: The host on which the exception occurred, or None if it occurred locally. 95 96 exception_handler = None 97 stderr_handler = None 98

99 -def _format_input_for_reporting(input, buffer):

100 if isinstance(input, list): 101 buffer.append(str(tuple(input))) 102 elif isinstance(input, tuple): 103 buffer.append(str(input)) 104 else: 105 buffer.append('(') 106 buffer.append(str(input)) 107 buffer.append(')')

108

109 -def _default_exception_handler(exception, op, input, host = None):

110 buffer = [] 111 if host: 112 buffer.append('From ') 113 buffer.append(host) 114 buffer.append(': ') 115 buffer.append(str(op)) 116 _format_input_for_reporting(input, buffer) 117 buffer.append(' ') 118 buffer.append(str(exception.__class__)) 119 buffer.append(': ') 120 buffer.append(str(exception)) 121 print >>sys.stderr, ''.join(buffer)

122

123 -def set_exception_handler(handler):

124 """Use C{handler} as the exception handler. 125 """ 126 global exception_handler 127 def wrap_provided_exception_handler(exception, op, input, host = None): 128 try: 129 handler(exception, op, input, host) 130 except Exception, e: 131 raise ExceptionHandlerException(e)

132 exception_handler = wrap_provided_exception_handler 133 134 exception_handler = _default_exception_handler 135

136 -def _default_stderr_handler(line, op, input, host = None):

137 buffer = [] 138 if host: 139 buffer.append('From ') 140 buffer.append(host) 141 buffer.append(': ') 142 buffer.append(str(op)) 143 _format_input_for_reporting(input, buffer) 144 buffer.append(': ') 145 buffer.append(line.rstrip()) 146 print >>sys.stderr, ''.join(buffer)

147

148 -def set_stderr_handler(handler):

149 """Use C{handler} as the stderr handler. 150 """ 151 def wrap_provided_stderr_handler(line, op, input, host = None): 152 try: 153 handler(line, op, input, host) 154 except Exception, e: 155 raise ExceptionHandlerException(e)

156 global stderr_handler 157 stderr_handler = wrap_provided_stderr_handler 158 159 stderr_handler = _default_stderr_handler 160

Source Code for Module osh.error