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value.

=head1 ALTERNATE SYNTAX

Using Perl 5.10 you can use L<perlsyn/"Switch statements"> (but please don't,
because that syntax has since been deprecated because there was too much
unexpected magical behaviour).

=for stopwords topicalizer

The C<catch> block is invoked in a topicalizer context (like a C<given> block),
but note that you can't return a useful value from C<catch> using the C<when>
blocks without an explicit C<return>.

This is somewhat similar to Perl 6's C<CATCH> blocks. You can use it to
concisely match errors:

  try {
    require Foo;
  } catch {
    when (/^Can't locate .*?\.pm in \@INC/) { } # ignore
    default { die $_ }
  };

=head1 CAVEATS

=over 4

=item *

C<@_> is not available within the C<try> block, so you need to copy your
argument list. In case you want to work with argument values directly via C<@_>
aliasing (i.e. allow C<$_[1] = "foo">), you need to pass C<@_> by reference:

  sub foo {
    my ( $self, @args ) = @_;
    try { $self->bar(@args) }
  }

or

  sub bar_in_place {
    my $self = shift;
    my $args = \@_;
    try { $_ = $self->bar($_) for @$args }
  }

=item *

C<return> returns from the C<try> block, not from the parent sub (note that
this is also how C<eval> works, but not how L<TryCatch> works):

  sub parent_sub {
    try {
      die;
    }
    catch {
      return;
    };

    say "this text WILL be displayed, even though an exception is thrown";
  }

Instead, you should capture the return value:

  sub parent_sub {
    my $success = try {
      die;
      1;
    };
    return unless $success;

    say "This text WILL NEVER appear!";
  }
  # OR
  sub parent_sub_with_catch {
    my $success = try {
      die;
      1;
    }
    catch {
      # do something with $_
      return undef; #see note
    };
    return unless $success;

    say "This text WILL NEVER appear!";
  }

Note that if you have a C<catch> block, it must return C<undef> for this to work,
since if a C<catch> block exists, its return value is returned in place of C<undef>
when an exception is thrown.

=item *

C<try> introduces another caller stack frame. L<Sub::Uplevel> is not used. L<Carp>
will not report this when using full stack traces, though, because
C<%Carp::Internal> is used. This lack of magic is considered a feature.

=for stopwords unhygienically

=item *

The value of C<$_> in the C<catch> block is not guaranteed to be the value of
the exception thrown (C<$@>) in the C<try> block.  There is no safe way to
ensure this, since C<eval> may be used unhygienically in destructors.  The only
guarantee is that the C<catch> will be called if an exception is thrown.

=item *

The return value of the C<catch> block is not ignored, so if testing the result
of the expression for truth on success, be sure to return a false value from
the C<catch> block:

  my $obj = try {
    MightFail->new;
  } catch {
    ...

    return; # avoid returning a true value;
  };

  return unless $obj;

=item *

C<$SIG{__DIE__}> is still in effect.

Though it can be argued that C<$SIG{__DIE__}> should be disabled inside of
C<eval> blocks, since it isn't people have grown to rely on it. Therefore in
the interests of compatibility, C<try> does not disable C<$SIG{__DIE__}> for
the scope of the error throwing code.

=item *

Lexical C<$_> may override the one set by C<catch>.

For example Perl 5.10's C<given> form uses a lexical C<$_>, creating some
confusing behavior:

  given ($foo) {
    when (...) {
      try {
        ...
      } catch {
        warn $_; # will print $foo, not the error
        warn $_[0]; # instead, get the error like this