isinstance() — Expert Examples

Returns True if an object is an instance of a given class or tuple of classes

EasyIntermediateAdvancedExpert

isinstance() performance and internals

Performance characteristics and CPython implementation details.

python
# isinstance() internals
import dis

def using_isinstance():
    pass

# Bytecode analysis
dis.dis(using_isinstance)

# Check if it's truly built-in
import builtins
print(f"\nisinstance is builtin: {hasattr(builtins, 'isinstance')}")
print(f"Type: {type(builtins.isinstance)}")

Understanding the internal implementation helps optimize hot paths in performance-critical code.

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