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Exception thingies!

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Nami-Doc 2014-09-23 23:28:24 +02:00
parent 40620d6816
commit b6ba516743
1 changed files with 29 additions and 4 deletions
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@ -700,15 +700,37 @@ try {
open 'foo';
CATCH {
when X::AdHoc { say "unable to open file !" }
# any other exception will be re-raised, since we don't have a `default`
# Any other exception will be re-raised, since we don't have a `default`
# Basically, if a `when` matches (or there's a `default`) marks the exception as
# "handled" so that it doesn't get re-thrown from the `CATCH`.
# You still can re-throw the exception (see below) by hand.
}
}
# You can throw an exception using `die`:
die X::AdHoc.new(payload => 'Error !');
# TODO warn
# TODO fail
# TODO CONTROL
# You can access the last exception with `$!` (usually used in a `CATCH` block)
# There are also some subtelties to exceptions. Some Perl 6 subs return a `Failure`,
# which is a kind of "unthrown exception". They're not thrown until you tried to look
# at their content, unless you call `.Bool`/`.defined` on them - then they're handled.
# (the `.handled` method is `rw`, so you can mark it as `False` back yourself)
#
# You can throw a `Failure` using `fail`. Note that if the pragma `use fatal` is on,
# `fail` will throw an exception (like `die`).
fail "foo"; # We're not trying to access the value, so no problem.
try {
fail "foo";
CATCH {
default { say "It threw because we try to get the fail's value!" }
}
}
# There is also another kind of exception: Control exceptions.
# Those are "good" exceptions, which happen when you change your program's flow,
# using operators like `return`, `next` or `last`.
# You can "catch" those with `CONTROL` (not 100% working in Rakudo yet).
### Packages
# Packages are a way to reuse code. Packages are like "namespaces", and any
@ -1351,6 +1373,9 @@ so 'ayc' ~~ / a [ b | y ] c /; # `True`. Obviously enough ...
# Note: the first-matching `or` still exists, but is now spelled `||`
'foo' ~~ / fo || foo /; # `fo` now.
### Extra: the MAIN subroutime
# The `MAIN` subroutine is called when you run a Perl 6 file directly.
# It's very powerful, because Perl 6 actually parses the argument