CODEWITHSUNDEEP
python
Ryex
Ryex

Reputation: 337

In python, what is contained in the info property of a module object?

I'm looking into creating a Plugin structure for a program and making it so even the core library is treated as plugins. in my research I came across this code that is dynamically importing modules.

def __initialize_def(self, module):
    """Attempt to load the definition"""

    # Import works the same for py files and package modules so strip!
    if module.endswith(".py"):
        name = module [:-3]
    else:
        name = module

    # Do the actual import
    __import__(name)
    definition = sys.modules[name]

    # Add the definition only if the class is available
    if hasattr(definition, definition.info["class"]):
        self.definitions[definition.info["name"]] = definition
        logging.info("Loaded %s" % name)

I have tried to understand what this code is doing and I've succeeded to a point. However, I simply can't understand the latter part of the code, specifically these two lines:

if hasattr(definition, definition.info["class"]):
    self.definitions[definition.info["name"]] = definition

I can't figure out what definition.info["<key>"] is referring to.

What is this .info[] dictionary and what does it hold? Is it common to all Python objects or only module objects? What is it useful for?

Upvotes: 1

Views: 240

Answers (2)

Tobu
Tobu

Reputation: 25436

Reserved names in Python generally begin with two underscores. You just stumbled on some piece of a larger codebase, that gives info module-scope values a special meaning. I don't think its authors chose a particularly good name for these, anyway; $FRAMEWORK_MODULE_INFO would be more explicit.

Upvotes: 0

Martin v. L&#246;wis
Martin v. L&#246;wis

Reputation: 127527

py> import sys,os
py> sys.modules["os"].info["class"]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'info'

So this info attribute must be specific to modules that can be used as plugins in this program.

Upvotes: 2

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