Given:
"fail" with configurable behavior
"no fatal" to make "fail" just warn
"use fatal" to make "fail" throw exceptions
A question came up on #perl6 for the following code:
no fatal;
class Foo {
use fatal;
method bar() { fail; }
}
Foo.bar;
That is, bar() picks up a lexically scoped "use fatal", but the caller
of bar desires non-fatal behavior.
Possible results and reasons for them:
* Warning -- For this to work, I think you would need an implicit
CATCH block wrapper around each statement in a "no fatal"
section. This could be simulated by wrapping the entire no fatal
section in a continuation closure which is then called inside a
CATCH block which warns and re-invokes the continuation... if
continuations can be re-invoked after exceptions. That's an
interesting question on it's own actually.
* Fatal exception -- This implies that the callee's lexically
scoped fatal preference wins, which might be a reasonable thing
in concept, but seems to present no control to the user of a
module when the module author has specified a preference.
Perhaps that's a good thing. Perhaps it's bad. I do see a
problem with a program that uses several modules, all of which
have different opinions about fatality...
* Warning -- Another reason that you might get a warning would be
that there is some sort of dynamically scoped imposition of a
non-fatal context from "no fatal". That seems the least likely
to me, but I thought that I'd bring it up.
This came up when someone was considering writing a module, and was
saying that he really wanted "use fatal" as the default for his modules.
That seems like a reasonable thing to want, but I'm not sure how it
could be controlled correctly.
--
Aaron Sherman <[EMAIL PROTECTED]>
Senior Systems Engineer and Toolsmith
"It's the sound of a satellite saying, 'get me down!'" -Shriekback
