[GitHub] thrift issue #1084: THRIFT-3773 Swift 3 Native Library

[apocolipse <gi...@git.apache.org>]

Github user apocolipse commented on the issue:

    https://github.com/apache/thrift/pull/1084
  
    Update:
    I've modified the generated Async clients to use a new `TAsyncResult<T>` parameter for callbacks rather than Optional Return/Error tuples.   Short version of why is that those parameters are always mutually exclusive, and there's no really good way to have a non-optional return or throw pattern for async.
    With the `TAsyncResult<T>`, non-optional return values are encapsulated within a throwing func in the enum, such that you can handle your do/catch block in a callback.  Consider the following example:
    
    ```swift
    /// normal: public func hello() throws -> String
    do {
      let world = try hello()
    } catch let e { handle(e) }
    
    /// async:   public func hello(completion: @escaping (TAsyncResult<String>) -> Void)
    hello() {
      do {
         let world = try $0.value()
      catch let e { handle(e) }
    }
    ```


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