Swift大型类的文件与命名空间组织方案咨询

Hey there! Sounds like you’ve already put in great work porting those persistent collections and adding full COW support—nice job getting that sorted out. When it comes to organizing Swift code for larger libraries like this, here’s a structured approach that aligns with Swift’s conventions and scales well:

文件组织策略 #

Swift favors one primary type per file (which you’re already doing for the main collections), but we can refine how supporting types are split out while keeping cohesion:

• Main collection files: Keep PersistentVector.swift, PersistentHashSet.swift, PersistentHashMap.swift as the top-level files for your public types. These should only contain the public-facing API and minimal references to internal types.
• Split internal support types: For non-public classes (like COW backing storage nodes, helper structs for hashing, or iterator types), move them into dedicated files grouped by their parent collection. For example:
  • PersistentVector+Internal.swift (holds vector-specific node types, COW storage helpers)
  • PersistentHashSet+Internal.swift (hash set’s bucket nodes, hashing utilities)
  • PersistentHashMap+Internal.swift (map entry nodes, key hashing helpers)
  • Alternatively, if you have shared utilities across collections (like common COW base logic), create a CollectionsShared directory with files like COWStorageBase.swift or PersistentCollectionUtilities.swift.

命名空间与类型分组 #

Swift doesn’t have explicit namespaces like some other languages, but we use modules and nested types to achieve the same effect:

• Leverage your module name: If this is a library, your module name (e.g., MutaborCollections) acts as the top-level namespace. Users will refer to your types as MutaborCollections.PersistentVector, or with an import MutaborCollections to use them directly.
• Nested internal types: For helper types that are only relevant to a single collection, nest them inside the public type. For example:

  public struct PersistentVector<Element> {
      // Public API here
      
      // Internal storage node, only accessible within the module
      internal class Node {
          // Node implementation
      }
      
      // COW storage wrapper, nested for clarity
      internal struct COWStorage {
          var storage: Node
          // COW logic here
      }
  }
  

  This keeps internal types tightly coupled to their parent collection and avoids polluting the global namespace.
• Use protocols for shared behavior: If all three collections share common persistent/COW behavior, define a PersistentCollection protocol in a separate PersistentCollection.swift file. This lets you share default implementations (via protocol extensions) while keeping each collection’s unique logic separate.

非公开辅助类型的处理 #

Since you have non-public classes tied to each collection, here’s how to keep them organized without cluttering the main files:

• Fileprivate vs Internal: Use fileprivate for types/functions that are only needed within a single file. For types that need to be accessed across multiple files in your module (e.g., a shared COW helper), use internal.
• Group related internal types: If you have a set of small helper types for a collection, you can either nest them (as above) or put them in a separate file with a clear suffix (like +Internal as mentioned earlier). This makes it easy to find which helpers belong to which collection.

COW相关代码的组织 #

Since you’ve added full COW support, you can optimize this for clarity and reusability:

• Extract shared COW logic: If all three collections use similar COW patterns, create a generic COWBackingStorage struct in a shared file. This can handle the reference counting and copy-on-write checks, so each collection doesn’t have to reimplement the same logic. For example:

  internal struct COWBackingStorage<Value> {
      private var _storage: Value
      private var isUnique: Bool
      
      mutating func ensureUnique() {
          // COW check and copy logic here
      }
      
      // Accessors for the storage
  }
  

• Keep collection-specific COW tweaks in the main file: Any COW logic that’s unique to a collection (like how a vector copies nodes vs how a hash map copies buckets) should stay in the collection’s main file or its internal companion file.

额外的最佳实践 #

• Add a README and module docs: Even if it’s for your own use, documenting the structure of your library will help you navigate it later. For example, note that +Internal files contain private implementation details.
• Use SwiftLint: It enforces Swift’s style guidelines, which will help keep your code consistent as it grows. Rules like file_types_order and nesting can help maintain clean organization.
• Test alongside implementation: Keep test files organized in a Tests directory mirroring your source structure (e.g., PersistentVectorTests.swift for the vector’s tests). This makes it easy to find tests for each component.

内容的提问来源于stack exchange，提问作者yeoman