Support multiple `@local` statements

[mkoculak]

Hey.
First of all, just upgraded to 0.5 and the improvements in code clarity thanks to the macro shorthands are awesome!

While translating my code, I tried inserting multiple local variables in a similar manner:

function localtest()
    @tasks for i in 1:100
        @local x = 0
        @local y = 0.
        x += i
        y += i
        println("x; $x, y: $y")
    end
end

which throws an error:

ERROR: LoadError: The @local macro may only be used inside of a @tasks block.

Wrapping both calls in a @local begin ... end block fixes it, but since documentation does not mention it and there are no examples, it might be good to either fix it or include it in the docs.
(though I see e.g. that Trapezoidal Integration example has multiple calls to local that work - is this equivalent to the macro?)

[carstenbauer]

(though I see e.g. that Trapezoidal Integration example has multiple calls to local that work - is this equivalent to the macro?)

No, this is not the same, as it has nothing to do with TaskLocalValue (although it also defines task local variables/values). In fact, it's just "good practice", the local keywords could just be dropped in this example.

[carstenbauer]

Actually, this is not a bug because we clearly document that multiple @local blocks are not allowed:

help?> @local
  @local name = value
  
  @local name::T = value


  Can be used inside a @tasks for ... end block to specify task-local values (TLV) via
  explicitly typed assignments. These values will be allocated once per task (rather
  than once per iteration) and can be re-used between different task-local iterations.

  There can only be a single @local block in a @tasks for ... end block. To specify
  multiple TLVs, use @local begin ... end. Compared to regular assignments, there are
  some limitations though, e.g. TLVs can't reference each other.

[...]

However, I don't remember if there was a good reason for it or whether we should try to support it (one thing that comes to mind is name clashes). I'll convert this issue into a feature request.

[carstenbauer]

(though I see e.g. that Trapezoidal Integration example has multiple calls to local that work - is this equivalent to the macro?)

No, this is not the same, as it has nothing to do with TaskLocalValue (although it also defines task local variables/values). In fact, it's just "good practice", the local keywords could just be dropped in this example.

f704536

[mkoculak]

Right, sorry - it did not occur to me I can also check the docstring of the macro. :)
So yeah - I don't think it is necessary, just maybe having it also stated in the documentation or inside of a code block example would make things clear for people that would miss the docstring like I did.