Reflection (computing)

Reflection is a programming language’s ability to inspect or modify a program’s structure and behavior while it runs. It can expose information about types, methods, objects, and execution.

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Runtime type information: Metadata that identifies an entity’s type while a program is running. Reflection often uses runtime type information to discover an object’s structure.
Dependency injection: A design technique in which a component receives its dependencies from an external system. Containers may inspect constructors and types to select and supply dependencies.
Static analysis: The examination of program properties without executing the program. Static analysis examines source or compiled code before runtime; reflection acts during execution.
Late binding: The resolution of a name or operation at runtime rather than during compilation. Reflective lookups defer decisions that ordinary code often makes earlier.
Introspection: The ability of a program to examine its own types, objects, and other runtime properties. Introspection is reflection’s inspection capability, distinct from changing program state.
Object-relational mapping: A technique for mapping objects in a program to records in a relational database. ORMs use type and field metadata to map program objects to database structures.
Compile-time metaprogramming: The generation or transformation of programs during compilation rather than during execution. Compile-time techniques can provide similar flexibility before a program runs.
Encapsulation: A design principle that hides internal state and exposes controlled interfaces. Reflection can bypass access boundaries that encapsulation is meant to preserve.
Dynamic method dispatch: Choosing which method implementation to call at runtime based on an object’s type or other conditions. Reflective method calls can resolve and invoke methods dynamically.
Serialization: The conversion of structured data into a representation suitable for storage or transmission. Serializers can inspect object fields and types to encode values automatically.