Re: block-scope finalization

[Philipp Janda <siffiejoe@...>]

Am 23.11.2015 um 21:09 schröbte Javier Guerra Giraldez:
> On Mon, Nov 23, 2015 at 2:38 PM, Coda Highland <chighland@gmail.com> wrote:
> > Deterministic finalization is a means to a particular end, but what is
> > that desired end? Ultimately: We want a specific function to be called
> > when control exits a block, no matter how it exits. In C++, we do this
> > using block scoping on a local variable. In Python, we have "finally:"
> > blocks and we have context managers and the "with" keyword; Java has
> > finally and try-with-parameters for the same.
>
> totally concur with you on this.

It's good enough for most cases and very easy to implement. (Btw., I 
have fixed that for you:)

    local function _finally( after, ok, ... )
      after()
      if ok then
        return ...
      else
        error( (...), 0 )
      end
    end

    function finally( main, after )
      return _finally( after, pcall( main ) )
    end


> far too many people say (not only about Lua) something on the lines
> of "professional programmers do RAII, therefore static languages are
> the only professional tools".

That's nonsense. Many static languages don't have RAII.
Joking aside, so far I have not found a better tool for generic resource 
management than RAII. Advantages of RAII over finally/using/with: You 
need only one language feature (destructors) instead of two (finalizers 
and finally), so the language is less complex/bloated (see C++!). And 
more importantly you only write your resource management code once and 
not multiple times scattered around in your source code.


Philipp