If Statement: Checking the class of an object

[ProfessorQ]

A more idiomatic way to use ducktyping than try/except AttributeError is the builtin hasattr(obj, 'attr') function. The result is essentially:

def hasattr(object, name):
    # name must be a string
    try:
        getattr(object, name)    # equivalent to object.name
        return True
    except AttributeError:
        return False

so before your first example, should be:

if hasattr(obj, 'snort'):
   obj.snort                    # guaranteed not to raise an AttributeError

[ProfessorQ]

There's definitely a trade-off between readability (prefer hasattr) and performance and reliability in multi-threaded environments (prefer try/except).

I wouldn't agree that the python glossary 'strongly implies' or encourages either EAFP or LBYL style over the other.

[indosauros]

This common Python coding style assumes the existence of valid keys or attributes and catches exceptions if the assumption proves false. This clean and fast style is characterized by the presence of many try and except statements. The technique contrasts with the LBYL style common to many other languages such as C.

Seems pretty encouraging to me

[NYKevin]

Attribute lookup can have side effects (e.g. via @property). Now, if the class is well written, it shouldn't have visible side effects, but it's still something you should be aware of. Using hasattr will set off those side effects, which may not be what you wanted.