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inspect: a module for getting information out of live Python objects

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Ka-Ping Yee 2001-02-27 14:43:21 +00:00
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\section{\module{inspect} ---
Inspect live objects}
\declaremodule{standard}{inspect}
\modulesynopsis{Extract information and source code from live objects.}
\index{inspect}
\versionadded{2.1}
The \code{inspect} module provides several useful functions
to help get information about live objects such as modules,
classes, methods, functions, tracebacks, frame objects, and
code objects. For example, it can help you examine the
contents of a class, retrieve the source code of a method,
extract and format the argument list for a function, or
get all the information you need to display a detailed traceback.
There are four main kinds of services provided by this module:
type checking, getting source code, inspecting classes
and functions, and examining the interpreter stack.
\subsection{Types and members
\label{inspect-types}}
The \function{getmembers()} function retrieves the members
of an object such as a class or module.
The nine functions whose names begin with ``is'' are mainly
provided as convenient choices for the second argument to
\function{getmembers()}. They also help you determine when
you can expect to find the following special attributes:
\begin{tableiii}{c|l|l}{}{Type}{Attribute}{Description}
\lineiii{module}{__doc__}{documentation string}
\lineiii{}{__file__}{filename (missing for built-in modules)}
\lineiii{}{}{}
\lineiii{class}{__doc__}{documentation string}
\lineiii{}{__module__}{name of module in which this class was defined}
\lineiii{}{}{}
\lineiii{method}{__doc__}{documentation string}
\lineiii{}{__name__}{name with which this method was defined}
\lineiii{}{im_class}{class object in which this method belongs}
\lineiii{}{im_func}{function object containing implementation of method}
\lineiii{}{im_self}{instance to which this method is bound, or \code{None}}
\lineiii{}{}{}
\lineiii{function}{__doc__}{documentation string}
\lineiii{}{__name__}{name with which this function was defined}
\lineiii{}{func_code}{code object containing compiled function bytecode}
\lineiii{}{func_defaults}{tuple of any default values for arguments}
\lineiii{}{func_doc}{(same as __doc__)}
\lineiii{}{func_globals}{global namespace in which this function was defined}
\lineiii{}{func_name}{(same as __name__)}
\lineiii{}{}{}
\lineiii{traceback}{tb_frame}{frame object at this level}
\lineiii{}{tb_lasti}{index of last attempted instruction in bytecode}
\lineiii{}{tb_lineno}{current line number in Python source code}
\lineiii{}{tb_next}{next inner traceback object (called by this level)}
\lineiii{}{}{}
\lineiii{frame}{f_back}{next outer frame object (this frame's caller)}
\lineiii{}{f_builtins}{built-in namespace seen by this frame}
\lineiii{}{f_code}{code object being executed in this frame}
\lineiii{}{f_exc_traceback}{traceback if raised in this frame, or \code{None}}
\lineiii{}{f_exc_type}{exception type if raised in this frame, or \code{None}}
\lineiii{}{f_exc_value}{exception value if raised in this frame, or \code{None}}
\lineiii{}{f_globals}{global namespace seen by this frame}
\lineiii{}{f_lasti}{index of last attempted instruction in bytecode}
\lineiii{}{f_lineno}{current line number in Python source code}
\lineiii{}{f_locals}{local namespace seen by this frame}
\lineiii{}{f_restricted}{0 or 1 if frame is in restricted execution mode}
\lineiii{}{f_trace}{tracing function for this frame, or \code{None}}
\lineiii{}{}{}
\lineiii{code}{co_argcount}{number of arguments (not including * or ** args)}
\lineiii{}{co_code}{string of raw compiled bytecode}
\lineiii{}{co_consts}{tuple of constants used in the bytecode}
\lineiii{}{co_filename}{name of file in which this code object was created}
\lineiii{}{co_firstlineno}{number of first line in Python source code}
\lineiii{}{co_flags}{bitmap: 1=optimized \code{|} 2=newlocals \code{|} 4=*arg \code{|} 8=**arg}
\lineiii{}{co_lnotab}{encoded mapping of line numbers to bytecode indices}
\lineiii{}{co_name}{name with which this code object was defined}
\lineiii{}{co_names}{tuple of names of local variables}
\lineiii{}{co_nlocals}{number of local variables}
\lineiii{}{co_stacksize}{virtual machine stack space required}
\lineiii{}{co_varnames}{tuple of names of arguments and local variables}
\lineiii{}{}{}
\lineiii{builtin}{__doc__}{documentation string}
\lineiii{}{__name__}{original name of this function or method}
\lineiii{}{__self__}{instance to which a method is bound, or \code{None}}
\end{tableiii}
\begin{funcdesc}{getmembers}{object\optional{, predicate}}
Return all the members of an object in a list of (name, value) pairs
sorted by name. If the optional \var{predicate} argument is supplied,
only members for which the predicate returns a true value are included.
\end{funcdesc}
\begin{funcdesc}{ismodule}{object}
Return true if the object is a module.
\end{funcdesc}
\begin{funcdesc}{isclass}{object}
Return true if the object is a class.
\end{funcdesc}
\begin{funcdesc}{ismethod}{object}
Return true if the object is a method.
\end{funcdesc}
\begin{funcdesc}{isfunction}{object}
Return true if the object is a Python function or unnamed (lambda) function.
\end{funcdesc}
\begin{funcdesc}{istraceback}{object}
Return true if the object is a traceback.
\end{funcdesc}
\begin{funcdesc}{isframe}{object}
Return true if the object is a frame.
\end{funcdesc}
\begin{funcdesc}{iscode}{object}
Return true if the object is a code.
\end{funcdesc}
\begin{funcdesc}{isbuiltin}{object}
Return true if the object is a built-in function.
\end{funcdesc}
\begin{funcdesc}{isroutine}{object}
Return true if the object is a user-defined or built-in function or method.
\end{funcdesc}
\subsection{Retrieving source code
\label{inspect-source}}
\begin{funcdesc}{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.
\end{funcdesc}
\begin{funcdesc}{getcomments}{object}
Return in a single string any lines of comments immediately preceding
the object's source code (for a class, function, or method), or at the
top of the Python source file (if the object is a module).
\end{funcdesc}
\begin{funcdesc}{getfile}{object}
Return the name of the (text or binary) file in which an object was defined.
This will fail with a TypeError if the object is a built-in module,
class, or function.
\end{funcdesc}
\begin{funcdesc}{getmodule}{object}
Try to guess which module an object was defined in.
\end{funcdesc}
\begin{funcdesc}{getsourcefile}{object}
Return the name of the Python source file in which an object was defined.
This will fail with a TypeError if the object is a built-in module,
class, or function.
\end{funcdesc}
\begin{funcdesc}{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.
\end{funcdesc}
\begin{funcdesc}{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.
\end{funcdesc}
\subsection{Classes and functions
\label{inspect-classes-functions}}
\begin{funcdesc}{getclasstree}{classes\optional{, unique}}
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 \var{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.
\end{funcdesc}
\begin{funcdesc}{getargspec}{func}
Get the names and default values of a function's arguments.
A tuple of four things is returned: (args, varargs, varkw, defaults).
\var{args} is a list of the argument names (it may contain nested lists).
\var{varargs} and \var{varkw} are the names of the * and ** arguments or
\code{None}.
\var{defaults} is a tuple of default argument values; if this tuple
has \var{n} elements, they correspond to the last \var{n} elements
listed in \var{args}.
\end{funcdesc}
\begin{funcdesc}{getargvalues}{frame}
Get information about arguments passed into a particular frame.
A tuple of four things is returned: (args, varargs, varkw, locals).
\var{args} is a list of the argument names (it may contain nested lists).
\var{varargs} and \var{varkw} are the names of the * and ** arguments or
\code{None}.
\var{locals} is the locals dictionary of the given frame.
\end{funcdesc}
\begin{funcdesc}{formatargspec}{args\optional{, varargs, varkw, defaults,
argformat, varargsformat, varkwformat, defaultformat}}
Format a pretty argument spec from the four values returned by getargspec.
The other four arguments are the corresponding optional formatting functions
that are called to turn names and values into strings.
\end{funcdesc}
\begin{funcdesc}{formatargvalues}{args\optional{, varargs, varkw, locals,
argformat, varargsformat, varkwformat, valueformat}}
Format a pretty argument spec from the four values returned by getargvalues.
The other four arguments are the corresponding optional formatting functions
that are called to turn names and values into strings.
\end{funcdesc}
\subsection{The interpreter stack
\label{inspect-stack}}
When the following functions return ``frame records'', each record
is a tuple of six items: the frame object, 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 \var{context} argument specifies the number of lines of
context to return, which are centered around the current line.
\begin{funcdesc}{getouterframes}{frame\optional{, context}}
Get a list of frame records for a frame and all higher (calling) frames.
\end{funcdesc}
\begin{funcdesc}{getinnerframes}{traceback\optional{, context}}
Get a list of frame records for a traceback's frame and all lower frames.
\end{funcdesc}
\begin{funcdesc}{currentframe}{}
Return the frame object for the caller's stack frame.
\end{funcdesc}
\begin{funcdesc}{stack}{\optional{context}}
Return a list of frame records for the stack above the caller's frame.
\end{funcdesc}
\begin{funcdesc}{trace}{\optional{context}}
Return a list of frame records for the stack below the current exception.
\end{funcdesc}

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"""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.
__version__ = 'Ka-Ping Yee <ping@lfw.org>, 1 Jan 2001'
import sys, types, string, 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
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) in [types.BuiltinFunctionType,
types.BuiltinMethodType]
def isroutine(object):
"""Return true if the object is any kind of function or method."""
return type(object) in [types.FunctionType, types.LambdaType,
types.MethodType, types.BuiltinFunctionType,
types.BuiltinMethodType]
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):
"""Try to guess which (text or binary) 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[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'
modulesbyfile = {}
def getmodule(object):
"""Try to guess which module an object was defined in."""
if isclass(object):
return sys.modules[object.__module__]
try:
file = getsourcefile(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[getsourcefile(module)] = module.__name__
if modulesbyfile.has_key(file):
return sys.modules[modulesbyfile[file]]
main = sys.modules['__main__']
try:
mainobject = getattr(main, object.__name__)
if mainobject is object: return main
except AttributeError: pass
builtin = sys.modules['__builtin__']
try:
builtinobject = getattr(builtin, object.__name__)
if builtinobject is object: return builtin
except AttributeError: pass
def getsourcefile(object):
"""Try to guess which Python source file an object was defined in."""
filename = getfile(object)
if filename[-4:] == '.pyc':
filename = filename[:-4] + '.py'
return filename
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))
lines = file.readlines()
file.close()
except (TypeError, IOError):
raise IOError, 'could not get source code'
if ismodule(object):
return lines, 0
if isclass(object):
name = object.__name__
matches = (['class', name], ['class', name + ':'])
for i in range(len(lines)):
if string.split(lines[i])[:2] in matches:
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):
try:
lnum = object.co_firstlineno - 1
except AttributeError:
raise IOError, 'could not find function definition'
else:
while lnum > 0:
if string.split(lines[lnum])[:1] == ['def']: 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: return None
if ismodule(object):
# Look for a comment block at the top of the file.
start = 0
if lines[0][:2] == '#!': start = 1
while start < len(lines) and string.strip(lines[start]) in ['', '#']:
start = start + 1
if 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 ''
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 = self.indent + 1
elif type == tokenize.DEDENT:
self.indent = 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 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)
if context > 0:
start = frame.f_lineno - 1 - context/2
try:
lines, lnum = findsource(frame)
start = max(start, 1)
start = min(start, len(lines) - context)
lines = lines[start:start+context]
index = frame.f_lineno - 1 - start
except:
lines = index = None
else:
lines = index = None
return (filename, frame.f_lineno, frame.f_code.co_name, lines, index)
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."""
tb = tb.tb_next
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)

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test_inspect

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source = '''# line 1
'A module docstring.'
import sys, inspect
# line 5
# line 7
def spam(a, b, c, d=3, (e, (f,))=(4, (5,)), *g, **h):
eggs(b + d, c + f)
# line 11
def eggs(x, y):
"A docstring."
global fr, st
fr = inspect.currentframe()
st = inspect.stack()
p = x
q = y / 0
# line 20
class StupidGit:
"""A longer,
indented
docstring."""
# line 27
def abuse(self, a, b, c):
"""Another
\tdocstring
containing
\ttabs
\t
"""
self.argue(a, b, c)
# line 40
def argue(self, a, b, c):
try:
spam(a, b, c)
except:
self.ex = sys.exc_info()
self.tr = inspect.trace()
# line 48
class MalodorousPervert(StupidGit):
pass
class ParrotDroppings:
pass
class FesteringGob(MalodorousPervert, ParrotDroppings):
pass
'''
# Functions tested in this suite:
# ismodule, isclass, ismethod, isfunction, istraceback, isframe, iscode,
# isbuiltin, isroutine, getmembers, getdoc, getfile, getmodule,
# getsourcefile, getcomments, getsource, getclasstree, getargspec,
# getargvalues, formatargspec, formatargvalues, currentframe, stack, trace
from test_support import TestFailed, TESTFN
import sys, imp, os, string
def test(assertion, message, *args):
if not assertion:
raise TestFailed, message % args
import inspect
file = open(TESTFN, 'w')
file.write(source)
file.close()
mod = imp.load_source('testmod', TESTFN)
def istest(func, exp):
obj = eval(exp)
test(func(obj), '%s(%s)' % (func.__name__, exp))
for other in [inspect.isbuiltin, inspect.isclass, inspect.iscode,
inspect.isframe, inspect.isfunction, inspect.ismethod,
inspect.ismodule, inspect.istraceback]:
if other is not func:
test(not other(obj), 'not %s(%s)' % (other.__name__, exp))
git = mod.StupidGit()
try:
1/0
except:
tb = sys.exc_traceback
istest(inspect.isbuiltin, 'sys.exit')
istest(inspect.isbuiltin, '[].append')
istest(inspect.isclass, 'mod.StupidGit')
istest(inspect.iscode, 'mod.spam.func_code')
istest(inspect.isframe, 'tb.tb_frame')
istest(inspect.isfunction, 'mod.spam')
istest(inspect.ismethod, 'mod.StupidGit.abuse')
istest(inspect.ismethod, 'git.argue')
istest(inspect.ismodule, 'mod')
istest(inspect.istraceback, 'tb')
test(inspect.isroutine(mod.spam), 'isroutine(mod.spam)')
test(inspect.isroutine([].count), 'isroutine([].count)')
classes = inspect.getmembers(mod, inspect.isclass)
test(classes ==
[('FesteringGob', mod.FesteringGob),
('MalodorousPervert', mod.MalodorousPervert),
('ParrotDroppings', mod.ParrotDroppings),
('StupidGit', mod.StupidGit)], 'class list')
tree = inspect.getclasstree(map(lambda x: x[1], classes), 1)
test(tree ==
[(mod.ParrotDroppings, ()),
(mod.StupidGit, ()),
[(mod.MalodorousPervert, (mod.StupidGit,)),
[(mod.FesteringGob, (mod.MalodorousPervert, mod.ParrotDroppings))
]
]
], 'class tree')
functions = inspect.getmembers(mod, inspect.isfunction)
test(functions == [('eggs', mod.eggs), ('spam', mod.spam)], 'function list')
test(inspect.getdoc(mod) == 'A module docstring.', 'getdoc(mod)')
test(inspect.getcomments(mod) == '# line 1\n', 'getcomments(mod)')
test(inspect.getmodule(mod.StupidGit) == mod, 'getmodule(mod.StupidGit)')
test(inspect.getfile(mod.StupidGit) == TESTFN, 'getfile(mod.StupidGit)')
test(inspect.getsourcefile(mod.spam) == TESTFN, 'getsourcefile(mod.spam)')
test(inspect.getsourcefile(git.abuse) == TESTFN, 'getsourcefile(git.abuse)')
def sourcerange(top, bottom):
lines = string.split(source, '\n')
return string.join(lines[top-1:bottom], '\n') + '\n'
test(inspect.getsource(git.abuse) == sourcerange(29, 39),
'getsource(git.abuse)')
test(inspect.getsource(mod.StupidGit) == sourcerange(21, 46),
'getsource(mod.StupidGit)')
test(inspect.getdoc(mod.StupidGit) ==
'A longer,\n\nindented\n\ndocstring.', 'getdoc(mod.StupidGit)')
test(inspect.getdoc(git.abuse) ==
'Another\n\ndocstring\n\ncontaining\n\ntabs\n\n', 'getdoc(git.abuse)')
test(inspect.getcomments(mod.StupidGit) == '# line 20\n',
'getcomments(mod.StupidGit)')
args, varargs, varkw, defaults = inspect.getargspec(mod.eggs)
test(args == ['x', 'y'], 'mod.eggs args')
test(varargs == None, 'mod.eggs varargs')
test(varkw == None, 'mod.eggs varkw')
test(defaults == None, 'mod.eggs defaults')
test(inspect.formatargspec(args, varargs, varkw, defaults) ==
'(x, y)', 'mod.eggs formatted argspec')
args, varargs, varkw, defaults = inspect.getargspec(mod.spam)
test(args == ['a', 'b', 'c', 'd', ['e', ['f']]], 'mod.spam args')
test(varargs == 'g', 'mod.spam varargs')
test(varkw == 'h', 'mod.spam varkw')
test(defaults == (3, (4, (5,))), 'mod.spam defaults')
test(inspect.formatargspec(args, varargs, varkw, defaults) ==
'(a, b, c, d=3, (e, (f,))=(4, (5,)), *g, **h)',
'mod.spam formatted argspec')
git.abuse(7, 8, 9)
istest(inspect.istraceback, 'git.ex[2]')
istest(inspect.isframe, 'mod.fr')
test(len(git.tr) == 2, 'trace() length')
test(git.tr[0][1:] == ('@test', 9, 'spam', [' eggs(b + d, c + f)\n'], 0),
'trace() row 1')
test(git.tr[1][1:] == ('@test', 18, 'eggs', [' q = y / 0\n'], 0),
'trace() row 2')
test(len(mod.st) >= 5, 'stack() length')
test(mod.st[0][1:] ==
('@test', 16, 'eggs', [' st = inspect.stack()\n'], 0),
'stack() row 1')
test(mod.st[1][1:] ==
('@test', 9, 'spam', [' eggs(b + d, c + f)\n'], 0),
'stack() row 2')
test(mod.st[2][1:] ==
('@test', 43, 'argue', [' spam(a, b, c)\n'], 0),
'stack() row 3')
test(mod.st[3][1:] ==
('@test', 39, 'abuse', [' self.argue(a, b, c)\n'], 0),
'stack() row 4')
# row 4 is in test_inspect.py
args, varargs, varkw, locals = inspect.getargvalues(mod.fr)
test(args == ['x', 'y'], 'mod.fr args')
test(varargs == None, 'mod.fr varargs')
test(varkw == None, 'mod.fr varkw')
test(locals == {'x': 11, 'p': 11, 'y': 14}, 'mod.fr locals')
test(inspect.formatargvalues(args, varargs, varkw, locals) ==
'(x=11, y=14)', 'mod.fr formatted argvalues')
args, varargs, varkw, locals = inspect.getargvalues(mod.fr.f_back)
test(args == ['a', 'b', 'c', 'd', ['e', ['f']]], 'mod.fr.f_back args')
test(varargs == 'g', 'mod.fr.f_back varargs')
test(varkw == 'h', 'mod.fr.f_back varkw')
test(inspect.formatargvalues(args, varargs, varkw, locals) ==
'(a=7, b=8, c=9, d=3, (e=4, (f=5,)), *g=(), **h={})',
'mod.fr.f_back formatted argvalues')
os.unlink(TESTFN)