"""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 <[email protected]>'

__date__ = '1 Jan 2001'

import sys, os, types, string, 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 = string.expandtabs(line)

return len(expline) - len(string.lstrip(expline))

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 = string.split(string.expandtabs(object.__doc__), '\n')

margin = None

for line in lines[1:]:

content = len(string.lstrip(line))

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 string.join(lines, '\n')

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):

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 string.lower(filename[-4:]) in ['.pyc', '.pyo']:

filename = filename[:-4] + '.py'

for suffix, mode, kind in imp.get_suffixes():

if 'b' in mode and string.lower(filename[-len(suffix):]) == suffix:

# Looks like a binary file. We want to only return a text file.

return None

if os.path.exists(filename):

return 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 = 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 string.strip(lines[start]) in ['', '#']:

start = start + 1

if start < len(lines) and lines[start][:1] == '#':

comments = []

end = start

while end < len(lines) and lines[end][:1] == '#':

comments.append(string.expandtabs(lines[end]))

end = end + 1

return string.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 string.lstrip(lines[end])[:1] == '#' and \

indentsize(lines[end]) == indent:

comments = [string.lstrip(string.expandtabs(lines[end]))]

if end > 0:

end = end - 1

comment = string.lstrip(string.expandtabs(lines[end]))

while comment[:1] == '#' and indentsize(lines[end]) == indent:

comments[:0] = [comment]

end = end - 1

if end < 0: break

comment = string.lstrip(string.expandtabs(lines[end]))

while comments and string.strip(comments[0]) == '#':

comments[:1] = []

while comments and string.strip(comments[-1]) == '#':

comments[-1:] = []

return string.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 ''

def getblock(lines):

"""Extract the block of code at the top of the given list of lines."""

indent = 0

started = 0

last = 0

tokens = tokenize.generate_tokens(ListReader(lines).readline)

for (type, token, (srow, scol), (erow, ecol), line) in tokens:

if not started:

if type == tokenize.NAME:

started = 1

elif type == tokenize.NEWLINE:

last = srow

elif type == tokenize.INDENT:

indent = indent + 1

elif type == tokenize.DEDENT:

indent = indent - 1

if indent == 0:

return lines[:last]

else:

raise ValueError, "unable to find block"

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 string.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 = step + 1

if op >= dis.HAVE_ARGUMENT:

opname = dis.opname[op]

value = ord(code[step]) + ord(code[step+1])*256

step = 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] = remain[-1] - 1

while remain[-1] == 0:

remain.pop()

size = count.pop()

stack[-size:] = [stack[-size:]]

if not remain: break

remain[-1] = 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 = 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 '(' + string.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 = spec + formatvalue(defaults[i - firstdefault])

specs.append(spec)

if varargs:

specs.append(formatvarargs(varargs))

if varkw:

specs.append(formatvarkw(varkw))

return '(' + string.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 '(' + string.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'

filename = getsourcefile(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-André 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 = addr + ord(table[i])

if addr > frame.f_lasti: break

lineno = 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 'catch me'

except:

return sys.exc_traceback.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_traceback, context)