Assignment compatibility
Assignment compatibility is a type-system relation determining whether a value or expression of one type can be assigned to an object of another type.
Fabulous Adventures in Data Structures and Algorithms
Assignment compatibility is the C# type-system rule determining whether an expression of one type may be assigned to a variable of another type.
- How it is used
- Models C# assignments as type relationships and uses them to explain generic variance.
- How deep it goes
- Defines the relation, works through covariant and contravariant interfaces, and stops short of a broader programming-language analysis.
- Examples
- Uses Animal, Giraffe, Tiger, IE<T>, and IC<T> to demonstrate ordinary, covariant, and contravariant assignments.
- What you can do after
- Understand why subtype assignments and generic interface assignments can preserve or reverse type relationships.
Read how Fabulous Adventures in Data Structures and Algorithms explains assignment compatibility →
Building User-Friendly DSLs
A directional type relation in which every value of one type can be assigned as a value of another type.
- How it is used
- Uses compatibility checks to validate typed attributes and values and to drive type-dependent rendering.
- How deep it goes
- Defines directional assignability but implements only equality-based compatibility, deferring richer subtype and coercion rules.
- Examples
- Demonstrates built-in amount, date range, percentage, and untype objects plus attribute-value mismatch reporting.
- What you can do after
- Diagnose typed attribute mismatches and understand how type-object equality controls validation and number rendering.
Read how Building User-Friendly DSLs explains assignment compatibility →
Modern C
Assignment compatibility is the C property that a value can be assigned to an object of a specified type under the language's permitted conversions.
- How it is used
- Uses assignment compatibility to validate macro arguments while preserving compiler diagnostics.
- How deep it goes
- Explains the definition, contrasts casts with assignment, and demonstrates compound-literal checking.
- Examples
- Demonstrates arithmetic tracing with +0 and pointer tracing with void* casts or compound-literal assignment.
- What you can do after
- Apply it via C compound literals to make the compiler check whether an expression is assignable to a chosen type.
Related concepts
- auto_ptrcontrasts with · std::auto_ptr was a legacy C++ standard-library smart pointer with ownership-transferring copy semantics, deprecated in C++11 and removed in C++17.
- contravarianceproduced by · Contravariance is a type-system relationship in which subtyping between parameterized types reverses the subtyping relationship between their type arguments, typically for input positions.
- category of typesimplements · The category of types is a category whose objects are types and whose morphisms express assignment compatibility.
- type compatibilityused by · Type compatibility is the relationship in which values of one type can be used where another type is expected under applicable language rules.
- compound literalused by · A compound literal is a C expression consisting of a parenthesized type name followed by an initializer that creates an unnamed object.
- morphismimplements · A morphism is a category-theoretic arrow connecting one object to another and participating in the category's composition structure.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.