Mutable object
A mutable object is an object whose state can be changed after it is created.
F# in Action: A Revised Edition of Get Programming with F#
Mutability is the property of data whose state can be changed after creation.
- How it is used
- Contrasts stateful object updates with explicit state-passing to motivate immutable F# design.
- How deep it goes
- Explains mutation through object models, debugging risks, F# syntax, and a worked gas-tank comparison.
- Examples
- Uses unreproducible bugs, multithreaded race conditions, a mutable car gas tank, and scoped StringBuilder accumulation.
- What you can do after
- Evaluate/understand when in-place state changes obscure behavior and when explicit returned state improves testability.
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Refactoring to Rust
Mutability is the property of a value or data structure that permits its contents to be changed after creation.
- How it is used
- Uses explicit mutability to control reassignment, in-place updates, and growing string buffers.
- How deep it goes
- Explains annotations, mutable references, scope-based reference dropping, String capacity, and reallocation without covering concurrent Rust details.
- Examples
- Uses integer variables, an artwork view counter, repeated string appends, and preallocated string capacity.
- What you can do after
- Apply it by declaring mutable Rust variables, passing mutable references, and choosing string capacity for repeated appends.
Julia as a Second Language
A mutable type is a Julia type whose instances can have their fields modified after creation.
- How it is used
- Enables functions and collection-like operations to update fields of Julia composite objects after construction.
- How deep it goes
- Defines mutability, demonstrates field updates, and explains why changing a type definition requires restarting the REPL.
- Examples
- Uses an archer spending arrows and a staged rocket adding or removing stages.
- What you can do after
- Build it from scratch: define a mutable struct and write functions that update its fields.
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Fabulous Adventures in Data Structures and Algorithms
A mutable data structure is a data structure whose contents can be changed after it is created.
- How it is used
- Uses mutation for convenient construction and direct updates when preserving multiple historical states is unnecessary.
- How deep it goes
- Defines mutation, contrasts copying costs, and demonstrates encapsulated C# trie-node operations without developing a general mutation theory.
- Examples
- Uses integer arrays, mutable trie nodes, and command-based undo-redo state as concrete examples.
- What you can do after
- Evaluate when direct mutation is simpler than version sharing, and build encapsulated mutable trie nodes in C#.
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Related concepts
- immutable collectioncontrasts with · An immutable collection is a collection whose membership and contents cannot be changed after creation.
- HttpContextincludes · HttpContext is the ASP.NET Core object representing the information, state, and features associated with a single HTTP request and its response.
- imperative programmingused by · Imperative programming is a programming paradigm that expresses computation as an ordered sequence of instructions specifying operations, control flow, or changes to state.
- structconfigures · A struct is a composite data type or structure that groups related fields or values into a single unit.
- Mapincludes · A map is an associative data structure that stores key-value pairs and supports retrieving values by key.
- StringBuilderincludes · StringBuilder is a mutable character-sequence type designed for efficiently constructing and modifying text through repeated operations.
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