Initialization and Finalization hooks

[Kevin Tew]

I'm trying to implement ruby BEGIN and END blocks.

I can generate the blocks just fine. I just need to generate pir so they
get called at the right time.
BEGIN{} and END {} semantic are described below.

I think that these are general use cases that should be provided by parrot.

Maybe the solution is two stacks of subs in the interpreter structure.
One for initialization and one for finalization which are traversable
and modifiable using opcodes or a specialized pmc.

My take is that he initialization stack gets executed just before :main
and the finalization stack gets executed just before interpreter
termination.
Initialization should occur in the order that compilation units are
loaded and secondarily in the order that BEGIN or initialization blocks
occur within a compilation unit.

Kevin

From
http://www.ruby-doc.org/docs/ruby-doc-bundle/Manual/man-1.4/syntax.html#BEGIN_proc

BEGIN

Examples:

BEGIN {
...
}

Syntax:

BEGIN '{'
expr..
'}'

Registers the initialize routine. The block followed after |BEGIN| is
evaluated before any other statement in that file (or string). If
multiple |BEGIN| blocks are given, they are evaluated in the appearing
order.

The |BEGIN| block introduce new local-variable scope. They don't share
local variables with outer statements.

The |BEGIN| statement can only appear at the toplevel.

END

Examples:

END {
...
}

Syntax:

END '{' expr.. '}'

Registers finalize routine. The block followed after |END| is evaluated
just before the interpreter termination. Unlike |BEGIN|, |END| blocks
shares their local variables, just like blocks.

The |END| statement registers its block only once at the first
execution. If you want to register finalize routines many times, use
at_exit
<http://www.ruby-doc.org/docs/ruby-doc-bundle/Manual/man-1.4/function.html#at_exit>.

The |END| statement can only appear at the toplevel. Also you cannot
cancel finalize routine registered by |END|.

[Leopold Toetsch]

Am Dienstag, 1. August 2006 23:21 schrieb Kevin Tew:
> Syntax:
>
>         END '{' expr.. '}'
>
> Registers finalize routine. The block followed after |END| is evaluated
> just before the interpreter termination. Unlike |BEGIN|, |END| blocks
> shares their local variables, just like blocks.

I've put together the current possiblities to achieve the effect of END.
I don't know if it's sufficient, though.

See the last 5 or so t/pmc/exception.t or r13768 - r13770.

leo