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-rw-r--r--better_exchook.py211
1 files changed, 211 insertions, 0 deletions
diff --git a/better_exchook.py b/better_exchook.py
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+
+# by Albert Zeyer, www.az2000.de
+# code under GPLv3+
+# 2011-04-15
+
+# This is a simple replacement for the standard Python exception handler (sys.excepthook).
+# In addition to what the standard handler does, it also prints all referenced variables
+# (no matter if local, global or builtin) of the code line of each stack frame.
+# See below for some examples and some example output.
+
+import sys
+
+def parse_py_statement(line):
+ state = 0
+ curtoken = ""
+ spaces = " \t\n"
+ ops = ".,;:+-*/%&=(){}[]^<>"
+ i = 0
+ def _escape_char(c):
+ if c == "n": return "\n"
+ elif c == "t": return "\t"
+ else: return c
+ while i < len(line):
+ c = line[i]
+ i += 1
+ if state == 0:
+ if c in spaces: pass
+ elif c in ops: yield ("op", c)
+ elif c == "#": state = 6
+ elif c == "\"": state = 1
+ elif c == "'": state = 2
+ else:
+ curtoken = c
+ state = 3
+ elif state == 1: # string via "
+ if c == "\\": state = 4
+ elif c == "\"":
+ yield ("str", curtoken)
+ curtoken = ""
+ state = 0
+ else: curtoken += c
+ elif state == 2: # string via '
+ if c == "\\": state = 5
+ elif c == "'":
+ yield ("str", curtoken)
+ curtoken = ""
+ state = 0
+ else: curtoken += c
+ elif state == 3: # identifier
+ if c in spaces + ops + "#\"'":
+ yield ("id", curtoken)
+ curtoken = ""
+ state = 0
+ i -= 1
+ else: curtoken += c
+ elif state == 4: # escape in "
+ curtoken += _escape_char(c)
+ state = 1
+ elif state == 5: # escape in '
+ curtoken += _escape_char(c)
+ state = 2
+ elif state == 6: # comment
+ curtoken += c
+ if state == 3: yield ("id", curtoken)
+ elif state == 6: yield ("comment", curtoken)
+
+def grep_full_py_identifiers(tokens):
+ tokens = list(tokens)
+ i = 0
+ pykeywords = set(["for","in","while","print","continue","break","if","else","elif","yield","def","class","try","except","import","pass","lambda"])
+ while i < len(tokens):
+ tokentype, token = tokens[i]
+ i += 1
+ if tokentype != "id": continue
+ while i+1 < len(tokens) and tokens[i] == ("op", ".") and tokens[i+1][0] == "id":
+ token += "." + tokens[i+1][1]
+ i += 2
+ if token == "": continue
+ if token in pykeywords: continue
+ if token[0] in ".0123456789": continue
+ yield token
+
+
+def output_limit():
+ return 300
+
+def output(s):
+ limit = output_limit()
+ if len(s) > limit:
+ s = s[:limit - 3] + "..."
+ sys.stderr.write(s)
+ sys.stderr.write("\n")
+ sys.stderr.flush()
+
+def debug_shell(user_ns, user_global_ns):
+ from IPython.Shell import IPShellEmbed,IPShell
+ ipshell = IPShell(argv=[], user_ns=user_ns, user_global_ns=user_global_ns)
+ #ipshell()
+ ipshell.mainloop()
+
+
+def better_exchook(etype, value, tb):
+ output("EXCEPTION")
+ output('Traceback (most recent call last):')
+ topFrameLocals,topFrameGlobals = None,None
+ try:
+ import linecache
+ limit = None
+ if hasattr(sys, 'tracebacklimit'):
+ limit = sys.tracebacklimit
+ n = 0
+ _tb = tb
+ def _resolveIdentifier(namespace, id):
+ obj = namespace[id[0]]
+ for part in id[1:]:
+ obj = getattr(obj, part)
+ return obj
+ def _trySet(old, func):
+ if old is not None: return old
+ try: return func()
+ except: return old
+ while _tb is not None and (limit is None or n < limit):
+ f = _tb.tb_frame
+ topFrameLocals,topFrameGlobals = f.f_locals,f.f_globals
+ lineno = _tb.tb_lineno
+ co = f.f_code
+ filename = co.co_filename
+ name = co.co_name
+ output(' File "%s", line %d, in %s' % (filename,lineno,name))
+ linecache.checkcache(filename)
+ line = linecache.getline(filename, lineno, f.f_globals)
+ if line:
+ line = line.strip()
+ output(' line: ' + line)
+ output(' locals:')
+ alreadyPrintedLocals = set()
+ for tokenstr in grep_full_py_identifiers(parse_py_statement(line)):
+ splittedtoken = tuple(tokenstr.split("."))
+ for token in map(lambda i: splittedtoken[0:i], range(1, len(splittedtoken) + 1)):
+ if token in alreadyPrintedLocals: continue
+ tokenvalue = None
+ tokenvalue = _trySet(tokenvalue, lambda: "<local> " + repr(_resolveIdentifier(f.f_locals, token)))
+ tokenvalue = _trySet(tokenvalue, lambda: "<global> " + repr(_resolveIdentifier(f.f_globals, token)))
+ tokenvalue = _trySet(tokenvalue, lambda: "<builtin> " + repr(_resolveIdentifier(f.f_builtins, token)))
+ tokenvalue = tokenvalue or "<not found>"
+ output(' ' + ".".join(token) + " = " + tokenvalue)
+ alreadyPrintedLocals.add(token)
+ if len(alreadyPrintedLocals) == 0: output(" no locals")
+ _tb = _tb.tb_next
+ n += 1
+
+ except Exception, e:
+ output("ERROR: cannot get more detailed exception info because:")
+ import traceback
+ for l in traceback.format_exc().split("\n"): output(" " + l)
+ output("simple traceback:")
+ traceback.print_tb(tb)
+
+ import types
+ def _some_str(value):
+ try: return str(value)
+ except: return '<unprintable %s object>' % type(value).__name__
+ def _format_final_exc_line(etype, value):
+ valuestr = _some_str(value)
+ if value is None or not valuestr:
+ line = "%s" % etype
+ else:
+ line = "%s: %s" % (etype, valuestr)
+ return line
+ if (isinstance(etype, BaseException) or
+ isinstance(etype, types.InstanceType) or
+ etype is None or type(etype) is str):
+ output(_format_final_exc_line(etype, value))
+ else:
+ output(_format_final_exc_line(etype.__name__, value))
+
+ debug = False
+ try:
+ import os
+ debug = int(os.environ["DEBUG"]) != 0
+ except: pass
+ if debug:
+ output("---------- DEBUG SHELL -----------")
+ debug_shell(user_ns=topFrameLocals, user_global_ns=topFrameGlobals)
+
+def install():
+ sys.excepthook = better_exchook
+
+if __name__ == "__main__":
+ # some examples
+ # this code produces this output: https://gist.github.com/922622
+
+ try:
+ x = {1:2, "a":"b"}
+ def f():
+ y = "foo"
+ x, 42, sys.stdin.__class__, sys.exc_info, y, z
+ f()
+ except:
+ better_exchook(*sys.exc_info())
+
+ try:
+ f = lambda x: None
+ f(x, y)
+ except:
+ better_exchook(*sys.exc_info())
+
+ # use this to overwrite the global exception handler
+ sys.excepthook = better_exchook
+ # and fail
+ finalfail(sys)