diff options
author | cinap_lenrek <cinap_lenrek@localhost> | 2011-05-03 11:25:13 +0000 |
---|---|---|
committer | cinap_lenrek <cinap_lenrek@localhost> | 2011-05-03 11:25:13 +0000 |
commit | 458120dd40db6b4df55a4e96b650e16798ef06a0 (patch) | |
tree | 8f82685be24fef97e715c6f5ca4c68d34d5074ee /sys/src/cmd/python/Doc/lib/libinspect.tex | |
parent | 3a742c699f6806c1145aea5149bf15de15a0afd7 (diff) |
add hg and python
Diffstat (limited to 'sys/src/cmd/python/Doc/lib/libinspect.tex')
-rw-r--r-- | sys/src/cmd/python/Doc/lib/libinspect.tex | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/sys/src/cmd/python/Doc/lib/libinspect.tex b/sys/src/cmd/python/Doc/lib/libinspect.tex new file mode 100644 index 000000000..85651f060 --- /dev/null +++ b/sys/src/cmd/python/Doc/lib/libinspect.tex @@ -0,0 +1,393 @@ +\section{\module{inspect} --- + Inspect live objects} + +\declaremodule{standard}{inspect} +\modulesynopsis{Extract information and source code from live objects.} +\moduleauthor{Ka-Ping Yee}{ping@lfw.org} +\sectionauthor{Ka-Ping Yee}{ping@lfw.org} + +\versionadded{2.1} + +The \module{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 eleven 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{tableiv}{c|l|l|c}{}{Type}{Attribute}{Description}{Notes} + \lineiv{module}{__doc__}{documentation string}{} + \lineiv{}{__file__}{filename (missing for built-in modules)}{} + \hline + \lineiv{class}{__doc__}{documentation string}{} + \lineiv{}{__module__}{name of module in which this class was defined}{} + \hline + \lineiv{method}{__doc__}{documentation string}{} + \lineiv{}{__name__}{name with which this method was defined}{} + \lineiv{}{im_class}{class object that asked for this method}{(1)} + \lineiv{}{im_func}{function object containing implementation of method}{} + \lineiv{}{im_self}{instance to which this method is bound, or \code{None}}{} + \hline + \lineiv{function}{__doc__}{documentation string}{} + \lineiv{}{__name__}{name with which this function was defined}{} + \lineiv{}{func_code}{code object containing compiled function bytecode}{} + \lineiv{}{func_defaults}{tuple of any default values for arguments}{} + \lineiv{}{func_doc}{(same as __doc__)}{} + \lineiv{}{func_globals}{global namespace in which this function was defined}{} + \lineiv{}{func_name}{(same as __name__)}{} + \hline + \lineiv{traceback}{tb_frame}{frame object at this level}{} + \lineiv{}{tb_lasti}{index of last attempted instruction in bytecode}{} + \lineiv{}{tb_lineno}{current line number in Python source code}{} + \lineiv{}{tb_next}{next inner traceback object (called by this level)}{} + \hline + \lineiv{frame}{f_back}{next outer frame object (this frame's caller)}{} + \lineiv{}{f_builtins}{built-in namespace seen by this frame}{} + \lineiv{}{f_code}{code object being executed in this frame}{} + \lineiv{}{f_exc_traceback}{traceback if raised in this frame, or \code{None}}{} + \lineiv{}{f_exc_type}{exception type if raised in this frame, or \code{None}}{} + \lineiv{}{f_exc_value}{exception value if raised in this frame, or \code{None}}{} + \lineiv{}{f_globals}{global namespace seen by this frame}{} + \lineiv{}{f_lasti}{index of last attempted instruction in bytecode}{} + \lineiv{}{f_lineno}{current line number in Python source code}{} + \lineiv{}{f_locals}{local namespace seen by this frame}{} + \lineiv{}{f_restricted}{0 or 1 if frame is in restricted execution mode}{} + \lineiv{}{f_trace}{tracing function for this frame, or \code{None}}{} + \hline + \lineiv{code}{co_argcount}{number of arguments (not including * or ** args)}{} + \lineiv{}{co_code}{string of raw compiled bytecode}{} + \lineiv{}{co_consts}{tuple of constants used in the bytecode}{} + \lineiv{}{co_filename}{name of file in which this code object was created}{} + \lineiv{}{co_firstlineno}{number of first line in Python source code}{} + \lineiv{}{co_flags}{bitmap: 1=optimized \code{|} 2=newlocals \code{|} 4=*arg \code{|} 8=**arg}{} + \lineiv{}{co_lnotab}{encoded mapping of line numbers to bytecode indices}{} + \lineiv{}{co_name}{name with which this code object was defined}{} + \lineiv{}{co_names}{tuple of names of local variables}{} + \lineiv{}{co_nlocals}{number of local variables}{} + \lineiv{}{co_stacksize}{virtual machine stack space required}{} + \lineiv{}{co_varnames}{tuple of names of arguments and local variables}{} + \hline + \lineiv{builtin}{__doc__}{documentation string}{} + \lineiv{}{__name__}{original name of this function or method}{} + \lineiv{}{__self__}{instance to which a method is bound, or \code{None}}{} +\end{tableiv} + +\noindent +Note: +\begin{description} +\item[(1)] +\versionchanged[\member{im_class} used to refer to the class that + defined the method]{2.2} +\end{description} + + +\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}{getmoduleinfo}{path} + Return a tuple of values that describe how Python will interpret the + file identified by \var{path} if it is a module, or \code{None} if + it would not be identified as a module. The return tuple is + \code{(\var{name}, \var{suffix}, \var{mode}, \var{mtype})}, where + \var{name} is the name of the module without the name of any + enclosing package, \var{suffix} is the trailing part of the file + name (which may not be a dot-delimited extension), \var{mode} is the + \function{open()} mode that would be used (\code{'r'} or + \code{'rb'}), and \var{mtype} is an integer giving the type of the + module. \var{mtype} will have a value which can be compared to the + constants defined in the \refmodule{imp} module; see the + documentation for that module for more information on module types. +\end{funcdesc} + +\begin{funcdesc}{getmodulename}{path} + Return the name of the module named by the file \var{path}, without + including the names of enclosing packages. This uses the same + algorithm as the interpreter uses when searching for modules. If + the name cannot be matched according to the interpreter's rules, + \code{None} is returned. +\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} + +\begin{funcdesc}{ismethoddescriptor}{object} + Return true if the object is a method descriptor, but not if ismethod() or + isclass() or isfunction() are true. + + This is new as of Python 2.2, and, for example, is true of int.__add__. + An object passing this test has a __get__ attribute but not a __set__ + attribute, but beyond that the set of attributes varies. __name__ is + usually sensible, and __doc__ often is. + + Methods implemented via descriptors that also pass one of the other + tests return false from the ismethoddescriptor() test, simply because + the other tests promise more -- you can, e.g., count on having the + im_func attribute (etc) when an object passes ismethod(). +\end{funcdesc} + +\begin{funcdesc}{isdatadescriptor}{object} + Return true if the object is a data descriptor. + + Data descriptors have both a __get__ and a __set__ attribute. Examples are + properties (defined in Python), getsets, and members. The latter two are + defined in C and there are more specific tests available for those types, + which is robust across Python implementations. Typically, data descriptors + will also have __name__ and __doc__ attributes (properties, getsets, and + members have both of these attributes), but this is not guaranteed. +\versionadded{2.3} +\end{funcdesc} + +\begin{funcdesc}{isgetsetdescriptor}{object} + Return true if the object is a getset descriptor. + + getsets are attributes defined in extension modules via \code{PyGetSetDef} + structures. For Python implementations without such types, this method will + always return \code{False}. +\versionadded{2.5} +\end{funcdesc} + +\begin{funcdesc}{ismemberdescriptor}{object} + Return true if the object is a member descriptor. + + Member descriptors are attributes defined in extension modules via + \code{PyMemberDef} structures. For Python implementations without such + types, this method will always return \code{False}. +\versionadded{2.5} +\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 \exception{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 \exception{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 + \exception{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 + \exception{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: \code{(\var{args}, + \var{varargs}, \var{varkw}, \var{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 \code{*} and + \code{**} arguments or \code{None}. + \var{defaults} is a tuple of default argument values or None if there are no + default arguments; 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: \code{(\var{args}, + \var{varargs}, \var{varkw}, \var{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 \code{*} and + \code{**} arguments or \code{None}. + \var{locals} is the locals dictionary of the given frame. +\end{funcdesc} + +\begin{funcdesc}{formatargspec}{args\optional{, varargs, varkw, defaults, + formatarg, formatvarargs, formatvarkw, formatvalue, join}} + + Format a pretty argument spec from the four values returned by + \function{getargspec()}. The format* 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, + formatarg, formatvarargs, formatvarkw, formatvalue, join}} + Format a pretty argument spec from the four values returned by + \function{getargvalues()}. The format* arguments are the + corresponding optional formatting functions that are called to turn + names and values into strings. +\end{funcdesc} + +\begin{funcdesc}{getmro}{cls} + Return a tuple of class cls's base classes, including cls, in + method resolution order. No class appears more than once in this tuple. + Note that the method resolution order depends on cls's type. Unless a + very peculiar user-defined metatype is in use, cls will be the first + element of the tuple. +\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. + +\begin{notice}[warning] +Keeping references to frame objects, as found in +the first element of the frame records these functions return, can +cause your program to create reference cycles. Once a reference cycle +has been created, the lifespan of all objects which can be accessed +from the objects which form the cycle can become much longer even if +Python's optional cycle detector is enabled. If such cycles must be +created, it is important to ensure they are explicitly broken to avoid +the delayed destruction of objects and increased memory consumption +which occurs. + +Though the cycle detector will catch these, destruction of the frames +(and local variables) can be made deterministic by removing the cycle +in a \keyword{finally} clause. This is also important if the cycle +detector was disabled when Python was compiled or using +\function{\refmodule{gc}.disable()}. For example: + +\begin{verbatim} +def handle_stackframe_without_leak(): + frame = inspect.currentframe() + try: + # do something with the frame + finally: + del frame +\end{verbatim} +\end{notice} + +The optional \var{context} argument supported by most of these +functions specifies the number of lines of context to return, which +are centered around the current line. + +\begin{funcdesc}{getframeinfo}{frame\optional{, context}} + Get information about a frame or traceback object. A 5-tuple + is returned, the last five elements of the frame's frame record. +\end{funcdesc} + +\begin{funcdesc}{getouterframes}{frame\optional{, context}} + Get a list of frame records for a frame and all outer frames. These + frames represent the calls that lead to the creation of \var{frame}. + The first entry in the returned list represents \var{frame}; the + last entry represents the outermost call on \var{frame}'s stack. +\end{funcdesc} + +\begin{funcdesc}{getinnerframes}{traceback\optional{, context}} + Get a list of frame records for a traceback's frame and all inner + frames. These frames represent calls made as a consequence of + \var{frame}. The first entry in the list represents + \var{traceback}; the last entry represents where the exception was + raised. +\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 caller's stack. The first + entry in the returned list represents the caller; the last entry + represents the outermost call on the stack. +\end{funcdesc} + +\begin{funcdesc}{trace}{\optional{context}} + Return a list of frame records for the stack between the current + frame and the frame in which an exception currently being handled + was raised in. The first entry in the list represents the caller; + the last entry represents where the exception was raised. +\end{funcdesc} |