How to find out what methods, properties, etc a python module possesses

Question

Lets say I import a module. In order for me to make the best use of it, I would like to know what properties, methods, etc. that I can use. Is there a way to find that out?

As an example: Determining running programs in Python

In this line:

os.system('WMIC /OUTPUT:C:\ProcessList.txt PROCESS get Caption,Commandline,Processid')

Let's say I wanted to also print out the memory consumed by the processes. How do I find out if that's possible? And what would be the correct 'label' for it? (just as the author uses 'Commandline', 'ProcessId')

Similarly, in this:

import win32com.client
def find_process(name):
    objWMIService = win32com.client.Dispatch("WbemScripting.SWbemLocator")
    objSWbemServices = objWMIService.ConnectServer(".", "root\cimv2")
    colItems = objSWbemServices.ExecQuery(
         "Select * from Win32_Process where Caption = '{0}'".format(name))
    return len(colItems)

print find_process("SciTE.exe")

How would I make the function also print out the memory consumed, the executable path, etc.?

Answer 1

As for Python modules, you can do

>>> import module
>>> help(module)

and you'll get a list of supported methods (more exactly, you get the docstring, which might not contain every single method). If you want that, you can use

>>> dir(module)

although now you'd just get a long list of all properties, methods, classes etc. in that module.

In your first example, you're calling an external program, though. Of course Python has no idea which features wmic.exe has. How should it?

Answer 2

dir(module) returns the names of the attributes of the module

module.__dict__ is the mapping between the keys and the attributes objects themselves

module.__dict__.keys() and dir(module) are lists having the same elements, though they are not equals because the elements aren't in same order in them

it seems that help(module) iswhat you really need

Answer 3

Python has a build in function called dir(). I'm not sure if this is what you are referring to, but fire up a interactive python console and type:

import datetime
dir(datetime)

This should give you a list of methods, properties and submodules

Answer 4

@ldmvcd

Ok, excuse me, I think you are a beginner and you don't see to what fundamental notions I am refering.

Objects are Python’s abstraction for data. All data in a Python program is represented by objects or by relations between objects. http://docs.python.org/reference/datamodel.html#the-standard-type-hierarchy

I don't understand why it is called "abstraction": for me an object is something real in the machine, a series of bits organized according certain rules to represent conceptual data or functionning.

Names refer to objects. Names are introduced by name binding operations. Each occurrence of a name in the program text refers to the binding of that name established in the innermost function block containing the use. http://docs.python.org/reference/executionmodel.html#naming-and-binding

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A namespace is a mapping from names to objects. Most namespaces are currently implemented as Python dictionaries, but that’s normally not noticeable in any way (except for performance), and it may change in the future. Examples of namespaces are: the set of built-in names (containing functions such as abs(), and built-in exception names); the global names in a module; and the local names in a function invocation. In a sense the set of attributes of an object also form a namespace. http://docs.python.org/tutorial/classes.html#a-word-about-names-and-objects

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By the way, I use the word attribute for any name following a dot — for example, in the expression z.real, real is an attribute of the object z. Strictly speaking, references to names in modules are attribute references: in the expression modname.funcname, modname is a module object and funcname is an attribute of it. In this case there happens to be a straightforward mapping between the module’s attributes and the global names defined in the module: they share the same namespace! http://docs.python.org/tutorial/classes.html#a-word-about-names-and-objects

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Namespaces are created at different moments and have different lifetimes. http://docs.python.org/tutorial/classes.html#a-word-about-names-and-objects

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The namespace for a module is automatically created the first time a module is imported. The main module for a script is always called main. http://docs.python.org/reference/executionmodel.html#naming-and-binding

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Well, a Python programm is a big machine that plays with objects, references to these objects , names of these objects, and namespaces in which are binded the names and the objects , namespaces being implemented as dictionaries.

So, you're right: when I refer to keys , I refer to names being the keys in the diverse namespaces. Names are arbitrary or not , according if the objects they have been created to name are user's objects or built-in objects.

I give advise you to read thoroughly the parts

3.1. Objects , values and types http://docs.python.org/reference/datamodel.html#the-standard-type-hierarchy

and

4.1. Naming and binding http://docs.python.org/reference/executionmodel.html#naming-and-binding