instance code

isinstance and issubclass

>>> class P(object):  # parent class
	pass

>>> class K(P):       # subclass
	pass

>>> k = K()           # instace
>>> isinstance(k, K)
True
>>> isinstance(k, P)
True
>>> isinstance(K, P)  # K is a class
False

>>> issubclass(K, P)
True
>>> issubclass(k, P)  # k is not a class

TypeError: issubclass() arg 1 must be a class

>>> isinstance(K, type)  # a class is an instace of type
True
>>> isinstance(k, type)  # not a class
False

to python subclass type class instance isinstance issubclass by korakot on Mar 09, 2006

Fix for nil object error in Rails test fixtures

If you're seeing errors like this when you run Rails tests:

# NoMethodError: You have a nil object when you didn't expect it!

You might need to edit test/test_helper.rb to make sure use_instantiated_fixtures is true:

self.use_instantiated_fixtures = true

Prior to 1.0, Rails automatically created instance variables out of fixtures. So if you had a fixture record named "foo", you could access it in your test as "@foo". As of 1.0, the default is to disable that feature, which breaks a lot of existing code. Mike Clark explains the change.

to rails test object fixtures variables error instance nil by brainpipe on Jan 11, 2006

parameterized instance variables

// useful when you want to obtain more than one instance of the same type of variable on the
// same page. i.e. two different addresses. credit goes to argv[0] in #rubyonrails on freenode

instance_variable_get("@#{address_type}_address").country.name

to ruby variable parameterized instance by mkovacs on Jan 09, 2006

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isinstance and issubclass

Fix for nil object error in Rails test fixtures

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