Dir function of the module

Dir () function
You can use the built-in Dir function to list the identifier for a module definition. Identifiers have functions, classes, and variables.
When you provide a module name for Dir (), it returns a list of the name of the module definition. If no argument is supplied, it returns a list of names defined in the current module.
Using the Dir function
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Example 8.4 using the Dir function

[[email protected] python]# python
Python 2.6.6 (r266:84292, Sep 4 2013, 07:46:00)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "Help", "copyright", "credits" or "license" for more information.
>>> Import Sys
>>> dir (SYS)
[' __displayhook__ ',  ' __doc__ ',  ' __excepthook__ ',  ' __name__ ',  ' __package__ ',  ' __stderr __ ',  ' __stdin__ ',  ' __stdout__ ',  ' _clear_type_cache ',  ' _current_frames ',,  ' _getframe ',   ' api_version ',  ' argv ',  ' builtin_module_names ',  ' byteorder ',  ' call_tracing ',  ' Callstats ',  ' copyright ',  ' displayhook ',  ' dont_write_bytecode ',  ' exc_clear ',  ' exc_info ',  ' exc_type ',  ' excepthook ',  ' exec_prefix ' ',  ' executable ',  ' exit ',  ' flags ',  ' Float_info ',  ' getcheckinterval ',  ' getdefaultencoding ',  ' getdlopenflags ',  ' Getfilesystemencoding ',  ' getprofile ',  ' getrecursionlimit ',  ' getrefcount ',,  ' getsizeof ',   ' gettrace ',  ' hexversion ',  ' maxint ',  ' maxsize ',  ' maxunicode ',  ' Meta_path ',  ' Modules ',  ' path ',  ' path_hooks ',  ' path_importer_cache ',  ' platform ', ',  ' prefix ',  ' PS1 ',  ' ps2 ',  ' Py3kwarniNg ',  ' setcheckinterval ',  ' setdlopenflags ',  ' setprofile ',  ' setrecursionlimit ',  ' Settrace ',  ' stderr ',  ' stdin ',  ' ' stdout ',  ' Subversion ',  ' version ',  ' Version_info ',   ' Warnoptions ']
>>> a=5
>>> dir ()
[' __builtins__ ', ' __doc__ ', ' __name__ ', ' __package__ ', ' a ', ' sys ']
>>> del A
>>> dir ()
[' __builtins__ ', ' __doc__ ', ' __name__ ', ' __package__ ', ' sys ']
>>>

How it works
First, let's take a look at using dir on the input sys module. We see that it contains a large list of attributes.
Next, we don't use it to pass parameters to the Dir function--by default, it returns the list of properties for the current module. Note that the input module is also part of the list.
To observe the function of Dir, we define a new variable A and assign it a value, and then we examine dir, and we observe that the same value is added to the list. We use the DEL statement to delete the variable/attribute in the current module, which is once again reflected in the output of Dir.
A note about Del--this statement is used to delete a variable/name after it is run. In this example, Del A, you will no longer be able to use the variable a--it as if it had never existed.

Dir function of the module