"""Get useful information from live Python objects.
This module encapsulates the interface provided by the internal special
attributes (func_*, co_*, im_*, tb_*, etc.) in a friendlier fashion.
It also provides some help for examining source code and class layout.
Here are some of the useful functions provided by this module:
ismodule(), isclass(), ismethod(), isfunction(), istraceback(),
isframe(), iscode(), isbuiltin(), isroutine() - check object types
getmembers() - get members of an object that satisfy a given condition
getfile(), getsourcefile(), getsource() - find an object's source code
getdoc(), getcomments() - get documentation on an object
getmodule() - determine the module that an object came from
getclasstree() - arrange classes so as to represent their hierarchy
getargspec(), getargvalues() - get info about function arguments
formatargspec(), formatargvalues() - format an argument spec
getouterframes(), getinnerframes() - get info about frames
currentframe() - get the current stack frame
stack(), trace() - get info about frames on the stack or in a traceback
"""
# This module is in the public domain. No warranties.
__author__ = 'Ka-Ping Yee <ping@lfw.org>'
__date__ = '1 Jan 2001'
import sys, os, types, re, dis, imp, tokenize
# ----------------------------------------------------------- type-checking
def ismodule(object):
"""Return true if the object is a module.
Module objects provide these attributes:
__doc__ documentation string
__file__ filename (missing for built-in modules)"""
return type(object) is types.ModuleType
def isclass(object):
"""Return true if the object is a class.
Class objects provide these attributes:
__doc__ documentation string
__module__ name of module in which this class was defined"""
return type(object) is types.ClassType or hasattr(object, '__bases__')
def ismethod(object):
"""Return true if the object is an instance method.
Instance method objects provide these attributes:
__doc__ documentation string
__name__ name with which this method was defined
im_class class object in which this method belongs
im_func function object containing implementation of method
im_self instance to which this method is bound, or None"""
return type(object) is types.MethodType
def isfunction(object):
"""Return true if the object is a user-defined function.
Function objects provide these attributes:
__doc__ documentation string
__name__ name with which this function was defined
func_code code object containing compiled function bytecode
func_defaults tuple of any default values for arguments
func_doc (same as __doc__)
func_globals global namespace in which this function was defined
func_name (same as __name__)"""
return type(object) in (types.FunctionType, types.LambdaType)
def istraceback(object):
"""Return true if the object is a traceback.
Traceback objects provide these attributes:
tb_frame frame object at this level
tb_lasti index of last attempted instruction in bytecode
tb_lineno current line number in Python source code
tb_next next inner traceback object (called by this level)"""
return type(object) is types.TracebackType
def isframe(object):
"""Return true if the object is a frame object.
Frame objects provide these attributes:
f_back next outer frame object (this frame's caller)
f_builtins built-in namespace seen by this frame
f_code code object being executed in this frame
f_exc_traceback traceback if raised in this frame, or None
f_exc_type exception type if raised in this frame, or None
f_exc_value exception value if raised in this frame, or None
f_globals global namespace seen by this frame
f_lasti index of last attempted instruction in bytecode
f_lineno current line number in Python source code
f_locals local namespace seen by this frame
f_restricted 0 or 1 if frame is in restricted execution mode
f_trace tracing function for this frame, or None"""
return type(object) is types.FrameType
def iscode(object):
"""Return true if the object is a code object.
Code objects provide these attributes:
co_argcount number of arguments (not including * or ** args)
co_code string of raw compiled bytecode
co_consts tuple of constants used in the bytecode
co_filename name of file in which this code object was created
co_firstlineno number of first line in Python source code
co_flags bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg
co_lnotab encoded mapping of line numbers to bytecode indices
co_name name with which this code object was defined
co_names tuple of names of local variables
co_nlocals number of local variables
co_stacksize virtual machine stack space required
co_varnames tuple of names of arguments and local variables"""
return type(object) is types.CodeType
def isbuiltin(object):
"""Return true if the object is a built-in function or method.
Built-in functions and methods provide these attributes:
__doc__ documentation string
__name__ original name of this function or method
__self__ instance to which a method is bound, or None"""
return type(object) is types.BuiltinFunctionType
def isroutine(object):
"""Return true if the object is any kind of function or method."""
return isbuiltin(object) or isfunction(object) or ismethod(object)
def getmembers(object, predicate=None):
"""Return all members of an object as (name, value) pairs sorted by name.
Optionally, only return members that satisfy a given predicate."""
results = []
for key in dir(object):
value = getattr(object, key)
if not predicate or predicate(value):
results.append((key, value))
results.sort()
return results
# -------------------------------------------------- source code extraction
def indentsize(line):
"""Return the indent size, in spaces, at the start of a line of text."""
expline = line.expandtabs()
return len(expline) - len(expline.lstrip())
def getdoc(object):
"""Get the documentation string for an object.
All tabs are expanded to spaces. To clean up docstrings that are
indented to line up with blocks of code, any whitespace than can be
uniformly removed from the second line onwards is removed."""
if hasattr(object, '__doc__') and object.__doc__:
lines = object.__doc__.expandtabs().split('\n')
margin = None
for line in lines[1:]:
content = len(line.lstrip())
if not content:
continue
indent = len(line) - content
if margin is None:
margin = indent
else:
margin = min(margin, indent)
if margin is not None:
for i in range(1, len(lines)):
lines[i] = lines[i][margin:]
return '\n'.join(lines)
def getfile(object):
"""Work out which source or compiled file an object was defined in."""
if ismodule(object):
if hasattr(object, '__file__'):
return object.__file__
raise TypeError, 'arg is a built-in module'
if isclass(object):
object = sys.modules.get(object.__module__)
if hasattr(object, '__file__'):
return object.__file__
raise TypeError, 'arg is a built-in class'
if ismethod(object):
object = object.im_func
if isfunction(object):
object = object.func_code
if istraceback(object):
object = object.tb_frame
if isframe(object):
if object.f_globals.has_key('__file__'):
return object.f_globals['__file__']
object = object.f_code
if iscode(object):
return object.co_filename
raise TypeError, 'arg is not a module, class, method, ' \
'function, traceback, frame, or code object'
def getmoduleinfo(path):
"""Get the module name, suffix, mode, and module type for a given file."""
filename = os.path.basename(path)
suffixes = map(lambda (suffix, mode, mtype):
(-len(suffix), suffix, mode, mtype), imp.get_suffixes())
suffixes.sort() # try longest suffixes first, in case they overlap
for neglen, suffix, mode, mtype in suffixes:
if filename[neglen:] == suffix:
return filename[:neglen], suffix, mode, mtype
def getmodulename(path):
"""Return the module name for a given file, or None."""
info = getmoduleinfo(path)
if info:
return info[0]
def getsourcefile(object):
"""Return the Python source file an object was defined in, if it exists."""
filename = getfile(object)
if filename[-4:].lower() in ('.pyc', '.pyo'):
filename = filename[:-4] + '.py'
for suffix, mode, kind in imp.get_suffixes():
if 'b' in mode and filename[-len(suffix):].lower() == suffix:
# Looks like a binary file. We want to only return a text file.
return None
if os.path.exists(filename):
return os.path.abspath(filename)
def getabsfile(object):
"""Return an absolute path to the source or compiled file for an object.
The idea is for each object to have a unique origin, so this routine
normalizes the result as much as possible."""
return os.path.normcase(
os.path.abspath(getsourcefile(object) or getfile(object)))
modulesbyfile = {}
def getmodule(object):
"""Return the module an object was defined in, or None if not found."""
if ismodule(object):
return object
if isclass(object):
return sys.modules.get(object.__module__)
try:
file = getabsfile(object)
except TypeError:
return None
if modulesbyfile.has_key(file):
return sys.modules[modulesbyfile[file]]
for module in sys.modules.values():
if hasattr(module, '__file__'):
modulesbyfile[getabsfile(module)] = module.__name__
if modulesbyfile.has_key(file):
return sys.modules[modulesbyfile[file]]
main = sys.modules['__main__']
if hasattr(main, object.__name__):
mainobject = getattr(main, object.__name__)
if mainobject is object:
return main
builtin = sys.modules['__builtin__']
if hasattr(builtin, object.__name__):
builtinobject = getattr(builtin, object.__name__)
if builtinobject is object:
return builtin
def findsource(object):
"""Return the entire source file and starting line number for an object.
The argument may be a module, class, method, function, traceback, frame,
or code object. The source code is returned as a list of all the lines
in the file and the line number indexes a line in that list. An IOError
is raised if the source code cannot be retrieved."""
try:
file = open(getsourcefile(object))
except (TypeError, IOError):
raise IOError, 'could not get source code'
lines = file.readlines()
file.close()
if ismodule(object):
return lines, 0
if isclass(object):
name = object.__name__
pat = re.compile(r'^\s*class\s*' + name + r'\b')
for i in range(len(lines)):
if pat.match(lines[i]):
return lines, i
else:
raise IOError, 'could not find class definition'
if ismethod(object):
object = object.im_func
if isfunction(object):
object = object.func_code
if istraceback(object):
object = object.tb_frame
if isframe(object):
object = object.f_code
if iscode(object):
if not hasattr(object, 'co_firstlineno'):
raise IOError, 'could not find function definition'
lnum = object.co_firstlineno - 1
pat = re.compile(r'^\s*def\s')
while lnum > 0:
if pat.match(lines[lnum]):
break
lnum -= 1
return lines, lnum
def getcomments(object):
"""Get lines of comments immediately preceding an object's source code."""
try:
lines, lnum = findsource(object)
except IOError:
return None
if ismodule(object):
# Look for a comment block at the top of the file.
start = 0
if lines and lines[0][:2] == '#!':
start = 1
while start < len(lines) and lines[start].strip() in ('', '#'):
start += 1
if start < len(lines) and lines[start][:1] == '#':
comments = []
end = start
while end < len(lines) and lines[end][:1] == '#':
comments.append(lines[end].expandtabs())
end += 1
return ''.join(comments)
# Look for a preceding block of comments at the same indentation.
elif lnum > 0:
indent = indentsize(lines[lnum])
end = lnum - 1
if end >= 0 and lines[end].lstrip()[:1] == '#' \
and indentsize(lines[end]) == indent:
comments = [lines[end].expandtabs().lstrip()]
if end > 0:
end -= 1
comment = lines[end].expandtabs().lstrip()
while comment[:1] == '#' and indentsize(lines[end]) == indent:
comments[:0] = [comment]
end -= 1
if end < 0:
break
comment = lines[end].expandtabs().lstrip()
while comments and comments[0].strip() == '#':
comments[:1] = []
while comments and comments[-1].strip() == '#':
comments[-1:] = []
return ''.join(comments)
class ListReader:
"""Provide a readline() method to return lines from a list of strings."""
def __init__(self, lines):
self.lines = lines
self.index = 0
def readline(self):
i = self.index
if i < len(self.lines):
self.index = i + 1
return self.lines[i]
else:
return ''
class EndOfBlock(Exception):
pass
class BlockFinder:
"""Provide a tokeneater() method to detect the end of a code block."""
def __init__(self):
self.indent = 0
self.started = 0
self.last = 0
def tokeneater(self, type, token, (srow, scol), (erow, ecol), line):
if not self.started:
if type == tokenize.NAME:
self.started = 1
elif type == tokenize.NEWLINE:
self.last = srow
elif type == tokenize.INDENT:
self.indent += 1
elif type == tokenize.DEDENT:
self.indent -= 1
if self.indent == 0:
raise EndOfBlock, self.last
def getblock(lines):
"""Extract the block of code at the top of the given list of lines."""
try:
tokenize.tokenize(ListReader(lines).readline, BlockFinder().tokeneater)
except EndOfBlock, eob:
return lines[:eob.args[0]]
def getsourcelines(object):
"""Return a list of source lines and starting line number for an object.
The argument may be a module, class, method, function, traceback, frame,
or code object. The source code is returned as a list of the lines
corresponding to the object and the line number indicates where in the
original source file the first line of code was found. An IOError is
raised if the source code cannot be retrieved."""
lines, lnum = findsource(object)
if ismodule(object):
return lines, 0
else:
return getblock(lines[lnum:]), lnum + 1
def getsource(object):
"""Return the text of the source code for an object.
The argument may be a module, class, method, function, traceback, frame,
or code object. The source code is returned as a single string. An
IOError is raised if the source code cannot be retrieved."""
lines, lnum = getsourcelines(object)
return ''.join(lines)
# --------------------------------------------------- class tree extraction
def walktree(classes, children, parent):
"""Recursive helper function for getclasstree()."""
results = []
classes.sort(lambda a, b: cmp(a.__name__, b.__name__))
for c in classes:
results.append((c, c.__bases__))
if children.has_key(c):
results.append(walktree(children[c], children, c))
return results
def getclasstree(classes, unique=0):
"""Arrange the given list of classes into a hierarchy of nested lists.
Where a nested list appears, it contains classes derived from the class
whose entry immediately precedes the list. Each entry is a 2-tuple
containing a class and a tuple of its base classes. If the 'unique'
argument is true, exactly one entry appears in the returned structure
for each class in the given list. Otherwise, classes using multiple
inheritance and their descendants will appear multiple times."""
children = {}
roots = []
for c in classes:
if c.__bases__:
for parent in c.__bases__:
if not children.has_key(parent):
children[parent] = []
children[parent].append(c)
if unique and parent in classes:
break
elif c not in roots:
roots.append(c)
for parent in children.keys():
if parent not in classes:
roots.append(parent)
return walktree(roots, children, None)
# ------------------------------------------------ argument list extraction
# These constants are from Python's compile.h.
CO_OPTIMIZED, CO_NEWLOCALS, CO_VARARGS, CO_VARKEYWORDS = 1, 2, 4, 8
def getargs(co):
"""Get information about the arguments accepted by a code object.
Three things are returned: (args, varargs, varkw), where 'args' is
a list of argument names (possibly containing nested lists), and
'varargs' and 'varkw' are the names of the * and ** arguments or None."""
if not iscode(co):
raise TypeError, 'arg is not a code object'
code = co.co_code
nargs = co.co_argcount
names = co.co_varnames
args = list(names[:nargs])
step = 0
# The following acrobatics are for anonymous (tuple) arguments.
for i in range(nargs):
if args[i][:1] in ('', '.'):
stack, remain, count = [], [], []
while step < len(code):
op = ord(code[step])
step += 1
if op >= dis.HAVE_ARGUMENT:
opname = dis.opname[op]
value = ord(code[step]) + ord(code[step+1])*256
step += 2
if opname in ('UNPACK_TUPLE', 'UNPACK_SEQUENCE'):
remain.append(value)
count.append(value)
elif opname == 'STORE_FAST':
stack.append(names[value])
remain[-1] -= 1
while remain[-1] == 0:
remain.pop()
size = count.pop()
stack[-size:] = [stack[-size:]]
if not remain:
break
remain[-1] -= 1
if not remain:
break
args[i] = stack[0]
varargs = None
if co.co_flags & CO_VARARGS:
varargs = co.co_varnames[nargs]
nargs += 1
varkw = None
if co.co_flags & CO_VARKEYWORDS:
varkw = co.co_varnames[nargs]
return args, varargs, varkw
def getargspec(func):
"""Get the names and default values of a function's arguments.
A tuple of four things is returned: (args, varargs, varkw, defaults).
'args' is a list of the argument names (it may contain nested lists).
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'defaults' is an n-tuple of the default values of the last n arguments."""
if not isfunction(func):
raise TypeError, 'arg is not a Python function'
args, varargs, varkw = getargs(func.func_code)
return args, varargs, varkw, func.func_defaults
def getargvalues(frame):
"""Get information about arguments passed into a particular frame.
A tuple of four things is returned: (args, varargs, varkw, locals).
'args' is a list of the argument names (it may contain nested lists).
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'locals' is the locals dictionary of the given frame."""
args, varargs, varkw = getargs(frame.f_code)
return args, varargs, varkw, frame.f_locals
def joinseq(seq):
if len(seq) == 1:
return '(' + seq[0] + ',)'
else:
return '(' + ', '.join(seq) + ')'
def strseq(object, convert, join=joinseq):
"""Recursively walk a sequence, stringifying each element."""
if type(object) in (types.ListType, types.TupleType):
return join(map(lambda o, c=convert, j=join: strseq(o, c, j), object))
else:
return convert(object)
def formatargspec(args, varargs=None, varkw=None, defaults=None,
formatarg=str,
formatvarargs=lambda name: '*' + name,
formatvarkw=lambda name: '**' + name,
formatvalue=lambda value: '=' + repr(value),
join=joinseq):
"""Format an argument spec from the 4 values returned by getargspec.
The first four arguments are (args, varargs, varkw, defaults). The
other four arguments are the corresponding optional formatting functions
that are called to turn names and values into strings. The ninth
argument is an optional function to format the sequence of arguments."""
specs = []
if defaults:
firstdefault = len(args) - len(defaults)
for i in range(len(args)):
spec = strseq(args[i], formatarg, join)
if defaults and i >= firstdefault:
spec += formatvalue(defaults[i - firstdefault])
specs.append(spec)
if varargs:
specs.append(formatvarargs(varargs))
if varkw:
specs.append(formatvarkw(varkw))
return '(' + ', '.join(specs) + ')'
def formatargvalues(args, varargs, varkw, locals,
formatarg=str,
formatvarargs=lambda name: '*' + name,
formatvarkw=lambda name: '**' + name,
formatvalue=lambda value: '=' + repr(value),
join=joinseq):
"""Format an argument spec from the 4 values returned by getargvalues.
The first four arguments are (args, varargs, varkw, locals). The
next four arguments are the corresponding optional formatting functions
that are called to turn names and values into strings. The ninth
argument is an optional function to format the sequence of arguments."""
def convert(name, locals=locals,
formatarg=formatarg, formatvalue=formatvalue):
return formatarg(name) + formatvalue(locals[name])
specs = []
for i in range(len(args)):
specs.append(strseq(args[i], convert, join))
if varargs:
specs.append(formatvarargs(varargs) + formatvalue(locals[varargs]))
if varkw:
specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
return '(' + ', '.join(specs) + ')'
# -------------------------------------------------- stack frame extraction
def getframeinfo(frame, context=1):
"""Get information about a frame or traceback object.
A tuple of five things is returned: the filename, the line number of
the current line, the function name, a list of lines of context from
the source code, and the index of the current line within that list.
The optional second argument specifies the number of lines of context
to return, which are centered around the current line."""
if istraceback(frame):
frame = frame.tb_frame
if not isframe(frame):
raise TypeError, 'arg is not a frame or traceback object'
# prefer to give filename the actual source file but if
# it does not exist, return the filename.
filename = getsourcefile(frame) or getfile(frame)
lineno = getlineno(frame)
if context > 0:
start = lineno - 1 - context/2
try:
lines, lnum = findsource(frame)
except IOError:
lines = index = None
else:
start = max(start, 1)
start = min(start, len(lines) - context)
lines = lines[start:start+context]
index = lineno - 1 - start
else:
lines = index = None
return (filename, lineno, frame.f_code.co_name, lines, index)
def getlineno(frame):
"""Get the line number from a frame object, allowing for optimization."""
# Written by Marc-Andre Lemburg; revised by Jim Hugunin and Fredrik Lundh.
lineno = frame.f_lineno
code = frame.f_code
if hasattr(code, 'co_lnotab'):
table = code.co_lnotab
lineno = code.co_firstlineno
addr = 0
for i in range(0, len(table), 2):
addr += ord(table[i])
if addr > frame.f_lasti:
break
lineno += ord(table[i+1])
return lineno
def getouterframes(frame, context=1):
"""Get a list of records for a frame and all higher (calling) frames.
Each record contains a frame object, filename, line number, function
name, a list of lines of context, and index within the context."""
framelist = []
while frame:
framelist.append((frame,) + getframeinfo(frame, context))
frame = frame.f_back
return framelist
def getinnerframes(tb, context=1):
"""Get a list of records for a traceback's frame and all lower frames.
Each record contains a frame object, filename, line number, function
name, a list of lines of context, and index within the context."""
framelist = []
while tb:
framelist.append((tb.tb_frame,) + getframeinfo(tb, context))
tb = tb.tb_next
return framelist
def currentframe():
"""Return the frame object for the caller's stack frame."""
try:
raise Exception('catch me')
except Exception:
return sys.exc_info()[2].tb_frame.f_back
if hasattr(sys, '_getframe'):
currentframe = sys._getframe
def stack(context=1):
"""Return a list of records for the stack above the caller's frame."""
return getouterframes(currentframe().f_back, context)
def trace(context=1):
"""Return a list of records for the stack below the current exception."""
return getinnerframes(sys.exc_info()[2], context)
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