Concrete type
A concrete type is a fully specified, directly implementable or instantiable type with a particular representation and behavior.
Julia as a Second Language
A concrete type is a type that can be directly instantiated or used as the representation of values rather than serving only as an abstract classification.
- How it is used
- Models instantiable game units beneath an abstract category so related units can participate in shared battle behavior.
- How deep it goes
- Defines instantiation, fields, hierarchy limits, and a dispatch implication; stops short of implementing primitive types.
- Examples
- Contrasts an Archer constructor with a failing Warrior() call and uses archers, pikemen, and knights in a battle simulator.
- What you can do after
- Build it from scratch: define instantiable warrior types under an abstract type and use them with shared battle methods.
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Go by Example
A concrete type is a non-interface Go type that specifies values with an underlying representation and may have methods.
- How it is used
- Uses concrete types as the initial implementation choice before shared behavior warrants an interface.
- How deep it goes
- Explains concrete types through sql.DB’s driver architecture and interface-discovery rationale, without detailing type representation.
- Examples
- Uses sql.DB with SQLite and PostgreSQL drivers, plus link.Shortener and sqlite.Shortener implementations.
- What you can do after
- Apply it by starting with concrete implementations and defining focused interfaces only after observing shared consumer needs.
Learn Rust in a Month of Lunches
A concrete type is a specific Rust type rather than an abstract type parameter or trait description.
- How it is used
- Distinguishes fixed Rust types from generic parameters and trait descriptions when reading function signatures.
- How deep it goes
- Defines concrete types, contrasts generic syntax, and works through closure type errors without covering boxing internals.
- Examples
- Uses fixed and generic return_item functions, undeclared MyType, and two identical-looking closures rejected as different types.
- What you can do after
- Evaluate whether a Rust signature names one fixed type, introduces a generic parameter, or accepts behavior through a trait bound.
Read how Learn Rust in a Month of Lunches explains concrete type →
Related concepts
- structincludes · A struct is a composite data type or structure that groups related fields or values into a single unit.
- primitive data typeincludes · A primitive data type is a fundamental, language-provided type for representing a basic value, rather than a composite of multiple values.
- sql.DBincludes · sql.DB is a Go database/sql handle that provides database operations while managing a pool of database connections.
- errors.Asused by · errors.As is a Go standard-library function that searches an error chain for a value assignable to a specified type and stores the result.
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