py_import/2

Availability::- use_module(library(janus)).(can be autoloaded)

[det]py_import(+Spec, +Options)

Import a Python module. Janus imports modules automatically when referred in py_call/2 and related predicates. Importing a module implies the module is loaded using Python's __import__() built-in and added to a table that maps Prolog atoms to imported modules. This predicate explicitly imports a module and allows it to be associated with a different name. This is useful for loading nested modules, i.e., a specific module from a Python package as well as for avoiding conflicts. For example, with the Python selenium package installed, we can do in Python:

>>> from selenium import webdriver
>>> browser = webdriver.Chrome()

Without this predicate, we can do

?- py_call('selenium.webdriver':'Chrome'(), Chrome).

For a single call this is fine, but for making multiple calls it gets cumbersome. With this predicate we can write this.

?- py_import('selenium.webdriver', []).
?- py_call(webdriver:'Chrome'(), Chrome).

By default, the imported module is associated to an atom created from the last segment of the dotted name. Below we use an explicit name.

?- py_import('selenium.webdriver', [as(browser)]).
?- py_call(browser:'Chrome'(), Chrome).

Errors: permission_error(import_as, py_module, As) if there is already a module associated with As.