Working with a module that you’re not familiar with? No internet? Somehow the docs are not accessible? Or simply feeling adventourous? Python has you covered. There are a few ways to get help Interactively. In this post, we will try a few of them.

The dir built-in

The dir built in is a very helpful one. If you call it without any arguments, that is just dir(), it will return the names available in the current scope. When passed with an argument, it would display the available attributes of the passed object (inherited or it’s own).

>>> import os
>>> dir(os)
['CLD_CONTINUED', 'CLD_DUMPED', 'CLD_EXITED', 'CLD_TRAPPED', 'EX_CANTCREAT', 'EX_CONFIG', 'EX_DATAERR', 'EX_IOERR', 'EX_NOHOST', 'EX_NOINPUT', 'EX_NOPERM', 'EX_NOUSER', 'EX_OK', 'EX_OSERR', 'EX_OSFILE', 'EX_PROTOCOL', 'EX_SOFTWARE', 'EX_TEMPFAIL', 'EX_UNAVAILABLE', 'EX_USAGE', 'F_LOCK', 'F_OK', 'F_TEST', 'F_TLOCK', 'F_ULOCK', 'MutableMapping', 'NGROUPS_MAX', 'O_ACCMODE', 'O_APPEND', 'O_ASYNC', 'O_CLOEXEC', 'O_CREAT', 'O_DIRECTORY', 'O_DSYNC', 'O_EXCL', 'O_EXLOCK', 'O_NDELAY', 'O_NOCTTY', 'O_NOFOLLOW', 'O_NONBLOCK', 'O_RDONLY', 'O_RDWR', 'O_SHLOCK', 'O_SYNC', 'O_TRUNC', 'O_WRONLY', 'PRIO_PGRP', 'PRIO_PROCESS', 'PRIO_USER', 'P_ALL', 'P_NOWAIT', 'P_NOWAITO', 'P_PGID', 'P_PID', 'P_WAIT', 'RTLD_GLOBAL', 'RTLD_LAZY', 'RTLD_LOCAL', 'RTLD_NODELETE', 'RTLD_NOLOAD', 'RTLD_NOW', 'R_OK', 'SCHED_FIFO', 'SCHED_OTHER', 'SCHED_RR', 'SEEK_CUR', 'SEEK_END', 'SEEK_SET', 'ST_NOSUID', 'ST_RDONLY', 'TMP_MAX', 'WCONTINUED', 'WCOREDUMP', 'WEXITED', 'WEXITSTATUS', 'WIFCONTINUED', 'WIFEXITED', 'WIFSIGNALED', 'WIFSTOPPED', 'WNOHANG', 'WNOWAIT', 'WSTOPPED', 'WSTOPSIG', 'WTERMSIG', 'WUNTRACED', 'W_OK', 'X_OK', '_Environ', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', '_execvpe', '_exists', '_exit', '_fwalk', '_get_exports_list', '_putenv', '_spawnvef', '_unsetenv', '_wrap_close', 'abort', 'access', 'altsep', 'chdir', 'chflags', 'chmod', 'chown', 'chroot', 'close', 'closerange', 'confstr', 'confstr_names', 'cpu_count', 'ctermid', 'curdir', 'defpath', 'device_encoding', 'devnull', 'dup', 'dup2', 'environ', 'environb', 'errno', 'error', 'execl', 'execle', 'execlp', 'execlpe', 'execv', 'execve', 'execvp', 'execvpe', 'extsep', 'fchdir', 'fchmod', 'fchown', 'fdopen', 'fork', 'forkpty', 'fpathconf', 'fsdecode', 'fsencode', 'fstat', 'fstatvfs', 'fsync', 'ftruncate', 'fwalk', 'get_blocking', 'get_exec_path', 'get_inheritable', 'get_terminal_size', 'getcwd', 'getcwdb', 'getegid', 'getenv', 'getenvb', 'geteuid', 'getgid', 'getgrouplist', 'getgroups', 'getloadavg', 'getlogin', 'getpgid', 'getpgrp', 'getpid', 'getppid', 'getpriority', 'getsid', 'getuid', 'initgroups', 'isatty', 'kill', 'killpg', 'lchflags', 'lchmod', 'lchown', 'linesep', 'link', 'listdir', 'lockf', 'lseek', 'lstat', 'major', 'makedev', 'makedirs', 'minor', 'mkdir', 'mkfifo', 'mknod', 'name', 'nice', 'open', 'openpty', 'pardir', 'path', 'pathconf', 'pathconf_names', 'pathsep', 'pipe', 'popen', 'pread', 'putenv', 'pwrite', 'read', 'readlink', 'readv', 'remove', 'removedirs', 'rename', 'renames', 'replace', 'rmdir', 'scandir', 'sched_get_priority_max', 'sched_get_priority_min', 'sched_yield', 'sendfile', 'sep', 'set_blocking', 'set_inheritable', 'setegid', 'seteuid', 'setgid', 'setgroups', 'setpgid', 'setpgrp', 'setpriority', 'setregid', 'setreuid', 'setsid', 'setuid', 'spawnl', 'spawnle', 'spawnlp', 'spawnlpe', 'spawnv', 'spawnve', 'spawnvp', 'spawnvpe', 'st', 'stat', 'stat_float_times', 'stat_result', 'statvfs', 'statvfs_result', 'strerror', 'supports_bytes_environ', 'supports_dir_fd', 'supports_effective_ids', 'supports_fd', 'supports_follow_symlinks', 'symlink', 'sync', 'sys', 'sysconf', 'sysconf_names', 'system', 'tcgetpgrp', 'tcsetpgrp', 'terminal_size', 'times', 'times_result', 'truncate', 'ttyname', 'umask', 'uname', 'uname_result', 'unlink', 'unsetenv', 'urandom', 'utime', 'wait', 'wait3', 'wait4', 'waitpid', 'walk', 'write', 'writev']
>>>

Coupled with getattr, you can actually write your own custom utilities to better inspect objects.

The help built-in

I guess I don’t have to tell you how help-ful this one can be?

Did you know the help built in is based on pydoc.help?

If you just call help without any arguments, it will launch an interactive help prompt where you can just type in names and it will display help for that. Here’s an example:

>>> help()

Welcome to Python 3.5's help utility!

If this is your first time using Python, you should definitely check out
the tutorial on the Internet at http://docs.python.org/3.5/tutorial/.

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules.  To quit this help utility and
return to the interpreter, just type "quit".

To get a list of available modules, keywords, symbols, or topics, type
"modules", "keywords", "symbols", or "topics".  Each module also comes
with a one-line summary of what it does; to list the modules whose name
or summary contain a given string such as "spam", type "modules spam".

help> list

help>

When you type in list and hit enter, it will show you the docs for the list built in. To quit, press q. As described in the text above, typing in “modules”, “keywords” etc will list what is available.

Interestingly the help functionality is built on top of pydoc so it will be able to help you with most of the installed modules (even the third party ones) as long as the modules have doctstrings available. Brilliant, no?

Now if you call the help callable with an argument, it will display help for that item. The above example for viewing the docs for list can be done this way too:

>>> help(list)

Neat, huh?

Using the pydoc Module

In the previous section, we mentioned pydoc. From the name, you can probably guess what it does. Just to be certain, let’s try this:

>>> import pydoc
>>> help(pydoc)

As you can read in there, the pydoc module generates documentation in html or text format for interactive usages (like in the previous section). It can read Python source files, parse the docstrings and generate helpful information for us. Pydoc module comes with your Python installation. So it is always available to you.

There are some interesting use cases of this module. You can run it from the command line. Just use pydoc <name> where the <name> is the name of a function, module, class etc. It will display the same interactive, generated docs we get from help(<name>).

And then pydoc -k <keyword> would search the keyword in the available modules’ synopsis.

If you would like to browse the docs on a web browser, you can run pydoc -b and it will run a server and open your browser, pointing to the address of the server. If you would like to set the port yourself, use pydoc -p <port> and then in the prompt, type “b” to open the browser. You can browse the docs and search as needed.

The inspect Module

The inspect module has some interesting use cases too. It can help us know more about different objects in runtime.

The following functions check for object types:

• ismodule()
• isclass()
• ismethod()
• isfunction()
• isgeneratorfunction()
• isgenerator()
• istraceback()
• isframe()
• iscode()
• isbuiltin()
• isroutine()

We can use the getmembers() function to get all the members of an object, class or module. We can filter the members by passing one of the above functions as the second argument.

>>> len(inspect.getmembers(os))
284
>>> len(inspect.getmembers(os, inspect.isclass))
9
>>>

The getdoc function can be used to retrieve available documentation from an object.

>>> inspect.getdoc(list)
"list() -> new empty list\nlist(iterable) -> new list initialized from iterable's items"

The inspect module has some other cool functions too. Do check them out. And of course, you know how! ;-)

>>> import inspect
>>> help(inspect)