Typed exceptions to use with NativeCall

X-NativeCall.pm6

# Add them if you've got them.

our class X::NativeCall::DeadObject is Exception {
    has $.status = "no longer valid for use";
    has $.type = "UNSPECIFIED";
    has $.lib = "any library";
    method message {
	"This object of type $.type is $.status with $.lib."
    }
}

our class X::NativeCall::CannotClone is Exception {
    has $.type = "UNSPECIFIED";
    method message {
	"Native object of type $.type cannot be cloned."
    }
}

our class X::NativeCall::OverflowProhibited is Exception {
    has $.dtype;
    has $.value;
    
    method message {
        my $dtype = " of " ~ $!dtype if $!dtype.chars;
        my $value = " by value" ~ $!value if $!value.chars;
        "Prohibited overflow$dtype$value because that is dangerous here.";
    }
}

our class X::NativeCall::NativeError is Exception {
    has $.errno = "";
    has $.error = "";
    has $.func = "";
    has $.lib = "";

    method message {
        my $m = "Unexpected error from native API call";
        $m ~= " ($.errno)" if $.errno.chars;
        $m ~= ": $.error" if $.error.chars;
        if $.func.chars or $.lib.chars {
            $m ~= " (in ";
            $m ~= " function $.func" if $.func.chars;
            $m ~= " library $.lib" if $.lib.chars;
            $m ~= ")";
        }
    }
}