raku - Raku(即 Perl6)中是否有范围/Num 等的 'clamp' 方法/子？

Question

Perl6 中是否有“clamp”或等效方法或子方法？
例如

my $range= (1.0 .. 9.9)
my $val=15.3;

my $clamped=$range.clamp($val);
# $clamped would be 9.9

$val= -1.3;
$clamped=$range.clamp($val);
# $clamped would be 1.0

Answer 1

您可能想探索的另一种技巧是使用 Proxy ，它允许您在从容器中获取或存储值时定义“钩子(Hook)”

sub limited-num(Range $range) is rw {
    my ($min, $max) = $range.minmax;
    my Numeric $store = $min;
    Proxy.new(
        FETCH => method () { $store },
        STORE => method ($new) {
            $store = max($min, min($max, $new));
        }
    )
}

# Note the use of binding operator `:=`
my $ln := limited-num(1.0 .. 9.9);
say $ln;     # OUTPUT: 1

$ln += 4.2;  
say $ln;     # OUTPUT: 5.2

$ln += 100;  
say $ln;     # OUTPUT: 9.9

$ln -= 50;   
say $ln;     # OUTPUT: 1

$ln = 0;     
say $ln;     # OUTPUT: 1

这个特殊的 limited-num将使用它的最小值进行初始化，但您也可以在声明时设置它

my $ln1 := limited-num(1.0 .. 9.9) = 5.5;
say $ln1;    # OUTPUT 5.5;

my $ln2 := limited-num(1.0 .. 9.9) = 1000;
say $ln2;    # OUTPUT 9.9