Python custom module and import

Question

I am following this example on how to package a python module. But installing my built package with pip, when I tried to use it, while the following works.

from towel_stuff import towel_utils

x = towel_utils.has_towel()
print(x)

And this also works,

import towel_stuff.towel_utils

x = towel_stuff.towel_utils.has_towel()
print(x)

I don't understand, why the following doesn't work.

import towel_stuff

x = towel_stuff.towel_utils.has_towel()
print(x)

Normally, for example if we want to use os.path, we don't need to write import os.path, but just import os is enough. So, with my built package, why do I have to give the full package path?

Of course I can use from towel_stuff import * to import everything, but was just curious why we don't need to give the full path for standard packages.

Sraw · Accepted Answer · 2020-01-04 23:31:51Z

2

Given the following structure:

towel_stuff
----__init__.py
----towel_utils

When you use import towel_stuff, the only file executed is __init__.py, so if you haven't imported towel_utils in __init__.py, it is not accessible at all.

So in short, when you use import a_module, you are and only are executing the __init__.py file in that module directory. If you want to access the a_module.file, you need to explicitly import it.

When you use import a_file, you are executing that file, as path is just a variable of os, so you can access it like os.path.

So the difference is, path is a variable in os while towel_utils is a submodule in towel_stuff. Or let's say path is an imported module in os which makes it become a variable.

edited Jan 4, 2020 at 23:31

answered Jan 4, 2020 at 23:25

Sraw

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larsks · Accepted Answer · 2020-01-04 20:27:28Z

1

Normally, for example if we want to use os.path, we don't need to write import os.path, but just import os is enough. So, with my built package, why do I have to give the full package path?

It all depends on how the module is constructed. For example, if in your towel_stuff module you included:

from towel_stuff import towel_utils

Then code that imported only towel_stuff would have access to towel_stuff.towel_utils without additional imports.

answered Jan 4, 2020 at 20:27

larsks

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