Re: clumsiness of pcall() syntax and how we deal with it

[Javier Guerra Giraldez <javier@...>]

On Tue, Apr 28, 2015 at 10:44 AM, Coda Highland <chighland@gmail.com> wrote:
> Speaking of meta-programming: There's always the option to introduce
> try/catch/end syntax in a preprocessor. :P

it's also very doable with anonymous functions (untested, and might be
better with xpcall):

local function onrets(catch, ok, res1, ...)
   if ok then
      return res1, ...
   else
      return catch(res1)
   end
end

function try(f,catch)
   return onrets(catch, pcall(f()))
end


----- use as:

try(function()

    -- this is the 'try' part

end,function(err)

    -- and on any error, this will be called

end)


if the 'try' part returns successfully, this will return all its
values.  if it signals an error, the 'catch' part is called.  any
returns from the catch part would be passed to the original caller, if
it signals a new error, it would be propagated out of the whole
expression.

-- 
Javier