DIP 1002 (TryElseExpression) added to the queue

[crimaniak via Digitalmars-d]

On Thursday, 29 September 2016 at 10:51:01 UTC, Nick Treleaven 
wrote:
> Assuming for a minute that we want some form of DIP1002, we 
> might be able to extend the `try` scope in an interesting way:
>
> try {
>     auto f = foo();
> }
> catch (Exception) {
>     ...
> }
> finally (bool ok) { // true if no exception
>     bar();
>     __guard (ok) f.baz();
>     f.baz(); // error: f not in scope
> }
>

My 5 cents, let's play:

  try {
   ...
  }
  catch() { }
  catch() { }
  then { // I don't like idea to use 'else' very much. Please, 
don't use 'else' with try!
   ...
  }
  finally {
  }

let's be more generic

  try {
   ...
  }
  catch() { }
  catch() { }
  then {
   ...
  }
  catch() { }
  catch() { }
  then {
   ...
  }
  catch() { }
  catch() { }
  ...
  finally {
  }

(Hello from Javascript! But we have common scope here.)

or use guard in a more obvious place

  try {

   // in this code exceptions are routed to attached catch() blocks

   catch(MyException); // yes, this guard looks as stand-alone 
catch() to avoid new keywords, for example. May be bad idea, I 
don't know.

   // oops, in this code MyException ignores attached catch() 
blocks because of guard

  }
  catch() { }
  catch() { }
  finally {
  }

or make it again more generic

  try {

   // in this code exceptions are routed to attached catch() 
blocks as usual

   // ... but now catch() block can also be places inside of try 
block
   catch(MyException){
     // process
     // goto finally
   }

   // oops, this code below of catch(MyException), so...

  }
  catch() { }
  catch() { }
  finally {
  }

As for me, last variant is the most straightforward.