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copied!<p><code>Person.name</code> is an instance of some type with a custom <code>__eq__</code> method. While <code>__eq__</code> normally returns a boolean(ish) value, it can actually return whatever you want, including a lambda. See <a href="http://docs.python.org/reference/datamodel.html#special-method-names" rel="nofollow noreferrer">Python special method names</a> for more on this and related methods.</p> <p>Probably the most confusing/misleading part of this (especially if you're used to other OO languages like Java) is that <code>Person.name</code> and <code>person.name</code> (where <code>person</code> is an instance of <code>Person</code>) don't have to have any relationship to each other. For example:</p> <pre><code>class Person(object): name = "name of class" def __init__(self): self.name = "name of instance" person = Person() print Person.name print person.name </code></pre> <p>This will print:</p> <blockquote> <pre><code>name of class name of instance </code></pre> </blockquote> <p>Note that the class property is just set in the class body, while the instance property is set in the <code>__init__</code> method.</p> <p>In your case, you'd set <code>Person.name</code> to the object with the custom <code>__eq__</code> method that returns a lambda, something like this:</p> <pre><code>class LambdaThingy(object): def __init__(self, attrname): self.__attrname = attrname def __eq__(self, other): return lambda x: getattr(x, self.__attrname) == other class Person(object): name = LambdaThingy('name') def __init__(self, name): self.name = name equals_fred = Person.name == "Fred" equals_barney = Person.name == "Barney" fred = Person("Fred") print equals_fred(fred) print equals_barney(fred) </code></pre> <p>This prints:</p> <pre><code>True False </code></pre> <p>This is certainly skirting the edge of being "too clever", so I'd be very cautious about using this in production code. An explicit lambda would probably be a lot clearer to future maintainers, even if it is a bit more verbose.</p>

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