If I want to access the list of instance variables of an object, I can call myObject.__dict__.keys(). I want to use this attribute to print out all instance variables of an object. I am hesitant to do this because __dict__ is a "secret" attribute, and I do not understand what this footnote means.
So is it wrong to use myObject.__dict__?
What the footnote means is that you shouldn't try to access __dict__ directly but instead check if the feature/behavior you want is available.
So instead of doing something like:
if "__some_attribute__" in obj.__dict__:
# do stuff
you should instead do:
try:
obj.some_action_i_want_to_do(...)
except AttributeError:
# doesn't provide the functionality I want
The reasons for this are because different objects might provide different internal references to a certain action but still provide the desired output.
If you want to list the "internals" for the sake of debugging and inspecting the current object, then dir() is the right way to do it.
dir() only gives the names; __dict__ also gives the objects themselves.That footnote is in reference to the __dict__ attribute of a module. The __dict__ attribute of an object carries no such warning (documentation).
You could use dir function to list all attributes of an object.
Using it for things like printing out members for debugging should be fine. But if that's all you're doing, check out pretty print.
http://docs.python.org/library/pprint.html
The main problem with __dict__, is it violates the implied visibility rules of objects that python has.
__dict__ issue seems like a bit of a rabbit hole but I'd like to understand it better. What do you mean by implied visibility rules?
__dict__ is that it leads to the idea that obj.__dict__['x'] is the same as obj.x, which is completely wrong. The difference is that obj.x invokes descriptors but __dict__ doesnt.
vars(myObject)stylistically, but that's orthogonal to your question. It gives the same dict.