Virtual method
A virtual method is an overridable method whose implementation is selected at runtime according to the receiver object's dynamic type.
Learn C++ by Example
A virtual function is a C++ member function whose implementation can be selected according to the object's dynamic type through polymorphic dispatch.
- How it is used
- Uses virtual methods to let different blob types compete through one common race interface.
- How deep it goes
- Explains pure virtual methods, overriding, v-table dispatch, destructor safety, and pointer-based use without detailing compiler-generated layouts.
- Examples
- Demonstrates StepperBlob, RandomBlob, a Blob race, assertions, random distributions, and a zero-valued test generator.
- What you can do after
- Build it from scratch by defining a polymorphic Blob interface and implementing interchangeable derived classes with tested behavior.
100 C++ Mistakes and How to Avoid Them
A virtual function is a C++ member function whose implementation can be dynamically selected through an object of a derived class.
- How it is used
- Uses virtual methods to customize inherited behavior and preserve polymorphic operations across base-class interfaces.
- How deep it goes
- Explains dispatch through pointers or references, override checking, and destructor consequences, but does not detail dispatch internals.
- Examples
- Demonstrates Shape, Square, and Circle examples containing a misspelled override and a missing virtual destructor.
- What you can do after
- Apply polymorphism with compiler-checked overrides and destruct safely through base-class pointers.
Read how 100 C++ Mistakes and How to Avoid Them explains virtual method →
The Quick Python Book, Fourth Edition
A virtual method is a method whose implementation can be dynamically selected according to the class of the object on which it is invoked.
- How it is used
- Uses superclass lookup to share methods across related Python classes while permitting subclass-specific replacements.
- How deep it goes
- Defines dynamic method lookup and inheritance, but stops short of implementation-level dispatch details.
- Examples
- Demonstrates inherited movement through Shape, Circle, coordinates, and a concrete c.move(3, 4) call.
- What you can do after
- Evaluate inherited method behavior by tracing subclass and superclass lookup in small Python class hierarchies.
Read how The Quick Python Book, Fourth Edition explains virtual method →
Related concepts
- polymorphismconfigures · Polymorphism is a programming-language capability that lets a common interface or operation work with values of different types while allowing behavior to vary by type or implementation.
- vtableuses · A vtable is a compiler- or runtime-generated table of function or method entries used to dynamically dispatch operations for polymorphic objects or types.
- overrideaddressed by · Overriding is defining a more specific implementation that replaces inherited behavior for a type or object while preserving the operation’s interface.
- methodkind of · A method is a callable operation associated with an object or type and invoked through that association.
- visitor design patternimplemented by · The Visitor pattern separates operations on an object structure into visitor objects, allowing operations to be added without changing the structure’s element classes.
- invariantcontrasts with · An invariant is a property or condition that remains true across the valid states, operations, or specified transformations of a system or computation.
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