[Draft]iOS.Architecture.16.Truth-information-flow-and-clear-responsibilities-immutability
Concept: Truth, Information Flow, Clear Responsibilities and Immutability
1. Truth
1.1 Single Source of Truth
单一的事实/真想来源
Ref[2] Ref[3]
"One core principle that is good to keep in mind when modelling various states is to try to stick to
a “single source of truth” as much as possible. One easy wayto look at this is that you should never
need to check for multiple conditions to determine what state you are in." Ref[2]
1.2 Truth vs
Ref[1]
2. Information Flow (Data Flow)
3. Clear Responsibilities
4. Immutability
google "immutable object in objective-c"
4.0 Mutable vs Immutable Object
4.1 Why immutable object?
Value Object
“In computer science, a value object is a small object that represents a simple entity
whose equality is not based on identity: i.e. two value objects are equal when they
have the same value, not necessarily being the same object.
Value objects should be immutable: this is required for the implicit contract that
two value objects created equal, should remain equal. It is also useful for value objects
to be immutable, as client code cannot put the value object in an invalid state or
introduce buggy behaviour after instantiation.” Ref[9]
Value Object and Mantle
"For an Objective-C class to be used as a value object, it needs to be immutable,
support value equality, implement proper hashing, and support NSCopying.
Mantle provides the latter three just by subclassing MTLModel. "
4.2 Immutability and Builder Pattern
Ref[4] Ref[5] Ref[8]
Too many parameters in initializer method
4.3 Builder Pattern in Objective-C and Swift
Objective-C Version
http://www.cnblogs.com/cwgk/p/9013260.html
Swift Version
Todo
4.4 Code Generation (DSL, ruby)
Ref[10]
4.5 Code Generation (remodel)
Ref[11] Ref[12]
Remodel Plugin
https://github.com/facebook/remodel/blob/master/PLUGINS.md
4.6 Code Generation (plank)
Ref[13]
4.7 Consistency
Ref[14]
Reference
1. Advanced iOS Application Architecture and Patterns
http://asciiwwdc.com/2014/sessions/229
2. Modelling state in Swift
https://medium.com/@johnsundell/modelling-state-in-swift-3751a4acb8f3
Rules:
A single source of truth
Making states exclusive
Rendering reactively
Handling state changes
Extracting information
3. Single source of truth
https://en.wikipedia.org/wiki/Single_source_of_truth
4. Immutability and Builder Pattern
http://kean.github.io/post/immutability-and-builder-pattern
- objc.io: Value Objects
- Wikipedia: Builder Pattern
- Wikipedia: Immutable Objects
- Concepts in Objective-C Programming: Object Mutability
5. Value Objects (Read Again)
https://www.objc.io/issues/7-foundation/value-objects/
6. Mutability, aliasing, and the caches you didn't know you had
https://garbagecollective.quora.com/Mutability-aliasing-and-the-caches-you-didnt-know-you-had
7. Boundaries (To Read)
https://www.destroyallsoftware.com/talks/boundaries
8. Improving Immutable Object Initialization in Objective-C
http://holko.pl/2015/05/12/immutable-object-initialization/
9. Simplifying Objective-C Value Objects with Mantle and the Builder Pattern (AAAA+)
https://spin.atomicobject.com/2015/11/02/objective-c-value-objects-mantle/
10. Objective-C Value Objects: Code Generation
https://spin.atomicobject.com/2015/12/16/objective-c-value-objects-code-generation/
11. Building and managing iOS model objects with Remodel
https://code.facebook.com/posts/1154141864616569/building-and-managing-ios-model-objects-with-remodel/
12. remodel
https://github.com/facebook/remodel
Remodel is a tool that helps iOS and OS X developers avoid repetitive code by generating Objective-C
models that support coding, value comparison, and immutability.
13. plank
A tool for generating immutable model objects https://pinterest.github.io/plank/
https://github.com/pinterest/plank/
https://github.com/plivesey/ConsistencyManager-iOS
