macros (AST rewriters) #11536

situation:

• sometimes i wish i could generate a piece of code based on some existing one, for example a construction function for an given interface

  interface MyConfig {
     name: string;
     values: number[];
  }
  function myConfigFrom(name: string, values: number[]) : MyConfig {
     return { name, values };
  }

problem: currently my options are

• either write it by hands (tedious monotonous work)
• put together a homemade code generator and run it as a pre-build step (lot of maintenance, non-standard)

solution:

• allow AST rewrites via decorators

  @rewrite(addContructorFunction)
  interface MyConfig {
     name: string;
     values: number[];
  }
  function addContructorFunction(node: ts.Node): ts.Node[] {
     return [node, toConstructorFunction(node as ts.InterfaceDeclaration)];
  }
  function toConstructorFunction(node: ts.IntefaceDeclaration): ts.FunctionDeclaration {
     // fun stuff goes here
  }