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19365
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1 """Handle exceptions in CGI scripts by formatting tracebacks into nice HTML.
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2
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3 To enable this module, do:
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4
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5 import cgitb; cgitb.enable()
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6
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7 at the top of your CGI script. The optional arguments to enable() are:
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8
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9 display - if true, tracebacks are displayed in the web browser
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10 logdir - if set, tracebacks are written to files in this directory
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11 context - number of lines of source code to show for each stack frame
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12
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13 By default, tracebacks are displayed but not saved, and context is 5.
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14
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15 Alternatively, if you have caught an exception and want cgitb to display it
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16 for you, call cgitb.handle(). The optional argument to handle() is a 3-item
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17 tuple (etype, evalue, etb) just like the value of sys.exc_info()."""
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18
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19 __author__ = 'Ka-Ping Yee'
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20 __version__ = '$Revision$'
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21
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22 def reset():
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23 """Return a string that resets the CGI and browser to a known state."""
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24 return '''<!--: spam
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25 Content-Type: text/html
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26
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27 <body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> -->
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28 <body bgcolor="#f0f0f8"><font color="#f0f0f8" size="-5"> --> -->
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29 </font> </font> </font> </script> </object> </blockquote> </pre>
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30 </table> </table> </table> </table> </table> </font> </font> </font>'''
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31
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32 __UNDEF__ = [] # a special sentinel object
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33 def small(text): return '<small>' + text + '</small>'
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34 def strong(text): return '<strong>' + text + '</strong>'
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35 def grey(text): return '<font color="#909090">' + text + '</font>'
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36
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37 def lookup(name, frame, locals):
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38 """Find the value for a given name in the given environment."""
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39 if name in locals:
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40 return 'local', locals[name]
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41 if name in frame.f_globals:
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42 return 'global', frame.f_globals[name]
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43 return None, __UNDEF__
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44
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45 def scanvars(reader, frame, locals):
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46 """Scan one logical line of Python and look up values of variables used."""
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47 import tokenize, keyword
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48 vars, lasttoken, parent, prefix = [], None, None, ''
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49 for ttype, token, start, end, line in tokenize.generate_tokens(reader):
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50 if ttype == tokenize.NEWLINE: break
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51 if ttype == tokenize.NAME and token not in keyword.kwlist:
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52 if lasttoken == '.':
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53 if parent is not __UNDEF__:
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54 value = getattr(parent, token, __UNDEF__)
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55 vars.append((prefix + token, prefix, value))
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56 else:
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57 where, value = lookup(token, frame, locals)
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58 vars.append((token, where, value))
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59 elif token == '.':
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60 prefix += lasttoken + '.'
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61 parent = value
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62 else:
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63 parent, prefix = None, ''
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64 lasttoken = token
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65 return vars
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66
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67 def html((etype, evalue, etb), context=5):
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68 """Return a nice HTML document describing a given traceback."""
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69 import sys, os, types, time, traceback, linecache, inspect, pydoc
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70
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71 if type(etype) is types.ClassType:
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72 etype = etype.__name__
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73 pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
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74 date = time.ctime(time.time())
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75 head = '<body bgcolor="#f0f0f8">' + pydoc.html.heading(
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76 '<big><big><strong>%s</strong></big></big>' % str(etype),
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77 '#ffffff', '#6622aa', pyver + '<br>' + date) + '''
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78 <p>A problem occurred in a Python script. Here is the sequence of
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79 function calls leading up to the error, in the order they occurred.'''
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80
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81 indent = '<tt>' + small(' ' * 5) + ' </tt>'
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82 frames = []
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83 records = inspect.getinnerframes(etb, context)
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84 for frame, file, lnum, func, lines, index in records:
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85 file = file and os.path.abspath(file) or '?'
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86 link = '<a href="file://%s">%s</a>' % (file, pydoc.html.escape(file))
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87 args, varargs, varkw, locals = inspect.getargvalues(frame)
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88 call = ''
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89 if func != '?':
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90 call = 'in ' + strong(func) + \
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91 inspect.formatargvalues(args, varargs, varkw, locals,
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92 formatvalue=lambda value: '=' + pydoc.html.repr(value))
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93
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94 highlight = {}
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95 def reader(lnum=[lnum]):
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96 highlight[lnum[0]] = 1
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97 try: return linecache.getline(file, lnum[0])
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98 finally: lnum[0] += 1
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99 vars = scanvars(reader, frame, locals)
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100
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101 rows = ['<tr><td bgcolor="#d8bbff">%s%s %s</td></tr>' %
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102 ('<big> </big>', link, call)]
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103 if index is not None:
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104 i = lnum - index
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105 for line in lines:
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106 num = small(' ' * (5-len(str(i))) + str(i)) + ' '
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107 line = '<tt>%s%s</tt>' % (num, pydoc.html.preformat(line))
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108 if i in highlight:
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109 rows.append('<tr><td bgcolor="#ffccee">%s</td></tr>' % line)
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110 else:
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111 rows.append('<tr><td>%s</td></tr>' % grey(line))
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112 i += 1
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113
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114 done, dump = {}, []
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115 for name, where, value in vars:
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116 if name in done: continue
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117 done[name] = 1
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118 if value is not __UNDEF__:
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119 if where == 'global': name = '<em>global</em> ' + strong(name)
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120 elif where == 'local': name = strong(name)
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121 else: name = where + strong(name.split('.')[-1])
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122 dump.append('%s = %s' % (name, pydoc.html.repr(value)))
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123 else:
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124 dump.append(name + ' <em>undefined</em>')
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125
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126 rows.append('<tr><td>%s</td></tr>' % small(grey(', '.join(dump))))
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127 frames.append('''<p>
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128 <table width="100%%" cellspacing=0 cellpadding=0 border=0>
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129 %s</table>''' % '\n'.join(rows))
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130
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131 exception = ['<p>%s: %s' % (strong(str(etype)), str(evalue))]
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132 if type(evalue) is types.InstanceType:
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133 for name in dir(evalue):
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134 value = pydoc.html.repr(getattr(evalue, name))
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135 exception.append('\n<br>%s%s =\n%s' % (indent, name, value))
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136
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137 import traceback
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138 return head + ''.join(frames) + ''.join(exception) + '''
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139
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140
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141 <!-- The above is a description of an error in a Python program, formatted
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142 for a Web browser because the 'cgitb' module was enabled. In case you
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143 are not reading this in a Web browser, here is the original traceback:
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144
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145 %s
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146 -->
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147 ''' % ''.join(traceback.format_exception(etype, evalue, etb))
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148
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149 class Hook:
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150 """A hook to replace sys.excepthook that shows tracebacks in HTML."""
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151
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152 def __init__(self, display=1, logdir=None, context=5):
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153 self.display = display # send tracebacks to browser if true
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154 self.logdir = logdir # log tracebacks to files if not None
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155 self.context = context # number of source code lines per frame
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156
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157 def __call__(self, etype, evalue, etb):
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158 self.handle((etype, evalue, etb))
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159
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160 def handle(self, info=None):
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161 import sys
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162 info = info or sys.exc_info()
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163 print reset()
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164
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165 try:
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166 text, doc = 0, html(info, self.context)
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167 except: # just in case something goes wrong
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168 import traceback
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169 text, doc = 1, ''.join(traceback.format_exception(*info))
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170
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171 if self.display:
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172 if text:
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173 doc = doc.replace('&', '&').replace('<', '<')
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174 print '<pre>' + doc + '</pre>'
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175 else:
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176 print doc
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177 else:
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178 print '<p>A problem occurred in a Python script.'
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179
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180 if self.logdir is not None:
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181 import os, tempfile
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182 name = tempfile.mktemp(['.html', '.txt'][text])
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183 path = os.path.join(self.logdir, os.path.basename(name))
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184 try:
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185 file = open(path, 'w')
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186 file.write(doc)
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187 file.close()
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188 print '<p> %s contains the description of this error.' % path
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189 except:
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190 print '<p> Tried to save traceback to %s, but failed.' % path
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191
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192 handler = Hook().handle
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193 def enable(display=1, logdir=None, context=5):
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194 """Install an exception handler that formats tracebacks as HTML.
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195
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196 The optional argument 'display' can be set to 0 to suppress sending the
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197 traceback to the browser, and 'logdir' can be set to a directory to cause
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198 tracebacks to be written to files there."""
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199 import sys
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200 sys.excepthook = Hook(display, logdir, context)
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