How to Determine Attribute Availability in Python: `hasattr()` vs. "Ask Forgiveness, Not Permission"?

Determine Attribute Availability

In Python, accessing an attribute of an object without checking its existence can result in AttributeError. To avoid this, it's crucial to determine if an attribute is present before attempting to access it.

hasattr() Function

One method to check for an attribute is the hasattr() function. It takes two arguments:

• The object to examine
• The name of the attribute

Returning True if the attribute exists, hasattr() is useful when you need to verify its presence without raising an exception.

a = SomeClass()
if hasattr(a, 'property'):
    a.property

Advantages and Drawbacks of hasattr()

Using hasattr() provides flexibility as it allows you to determine attribute availability without triggering an exception. However, it can introduce an additional level of complexity to your code.

Ask Forgiveness, Not Permission

An alternative approach, commonly used in Python, is the "ask forgiveness, not permission" philosophy. It involves accessing the attribute and catching the potential AttributeError exception gracefully.

try:
    a.property
except AttributeError:
    # Handle the absence of the attribute

This approach is generally faster than using hasattr(), especially if the attribute is likely to exist most of the time. However, it's crucial to appropriately handle the exception when it occurs.

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