$ python
>>> import sys
>>> dir(sys) # get list of attributes for sys module
['__displayhook__', '__doc__', '__excepthook__', '__name__', '__stderr__', '__stdin__', '__stdout__', '_getframe', 'api_version', 'argv', 'builtin_module_names', 'byteorder', 'call_tracing', 'callstats', 'copyright', 'displayhook', 'exc_clear', 'exc_info', 'exc_type', 'excepthook', 'exec_prefix', 'executable', 'exit', 'getcheckinterval', 'getdefaultencoding', 'getdlopenflags', 'getfilesystemencoding', 'getrecursionlimit', 'getrefcount', 'hexversion', 'maxint', 'maxunicode', 'meta_path','modules', 'path', 'path_hooks', 'path_importer_cache', 'platform', 'prefix', 'ps1', 'ps2', 'setcheckinterval', 'setdlopenflags', 'setprofile', 'setrecursionlimit', 'settrace', 'stderr', 'stdin', 'stdout', 'version', 'version_info', 'warnoptions']
>>> dir() # get list of attributes for current module
['__builtins__', '__doc__', '__name__', 'sys']
>>>
>>> a = 5 # create a new variable 'a'
>>> dir()
['__builtins__', '__doc__', '__name__', 'a', 'sys']
>>>
>>> del a # delete/remove a name
>>>
>>> dir()
['__builtins__', '__doc__', '__name__', 'sys']
>>>
First, we see the usage of dir on the importedsys module. We can see the huge list of attributes that it contains.
Next, we use thedir function without passing parameters to it - by default, it returns the list of attributes for the current module. Notice that the list of imported modules is also part of this list.In order to observe the dir in action, we define a new variablea and assign it a value and then check dir and we observe that there is an additional value in the list of the same name. We remove the variable/attribute of the current module using thedel statement and the change is reflected again in the output of thedir function.
A note ondel - this statement is used to delete a variable/name and after the statement has run, in this casedel a, you can no longer access the variablea - it is as if it never existed before at all.