Type error
A type error is a violation of a program’s type rules in which a value or expression has a type incompatible with an operation or context.
The Quick Python Book, Fourth Edition
TypeError is a Python built-in exception class raised when an operation or function receives a value of an inappropriate type.
- How it is used
- Uses TypeError to reject inputs that violate a function’s or dictionary subclass’s type requirements.
- How deep it goes
- Works through explicit checks, raising, and catching TypeError; does not examine exception internals.
- Examples
- Demonstrates non-iterable input, unhashable dictionary keys, and non-string keys or values in a dictionary subclass.
- What you can do after
- Build it from scratch: validate a string-only dictionary on both assignment and initialization, raising TypeError for invalid entries.
Read how The Quick Python Book, Fourth Edition explains type error →
Python How-To
TypeError is the Python exception raised when an operation or function receives an object of an inappropriate type or an incompatible kind of argument.
- How it is used
- Uses TypeError to diagnose incompatible operations and reject arguments that violate an interface’s expected type.
- How deep it goes
- Explains occurrence, explicit raising, and handling practice, but does not detail exception internals or subclass design.
- Examples
- Uses dictionary sorting, invalid Task construction, tuple item assignment, and deliberate test failures.
- What you can do after
- Apply TypeError by recognizing incompatible operations, raising it for invalid arguments, and practicing its handling in tests.
Related concepts
- exceptionkind of · An exception is a runtime signal or object representing an abnormal condition that interrupts ordinary program flow and may be handled or propagated.
- raise statementused by · A raise statement is a language construct that explicitly signals an exception during program execution, optionally specifying the exception or its associated value.
- try-catch statementused by · A try-catch statement is a control-flow construct that executes code under exception handling and transfers control to a matching handler when an exception is raised.
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