模式匹配
my $name = "twostraws";
given $name {
when "bilbo" { say "Hello, Bilbo Baggins!"}
when "twostraws" { say "Hello, Paul Hudson!" }
default { say "身份驗證失敗" }
}
同時檢查名字和密碼
my $name = "twostraws";
my $password = "fr0st1es";
given ($name, $password) {
when ("bilbo", "bagg1n5") { say "Hello, Bilbo Baggins!" }
when ("twostraws", "fr0st1es") { say "Hello, Paul Hudson!" }
default { say "你是誰?" }
}
使用單個元組
my $authentication = ("twostraws", "fr0st1es");
given $authentication {
when ("bilbo", "bagg1n5") { say "Hello, Bilbo Baggins!" }
when ("twostraws", "fr0st1es") { say "Hello, Paul Hudson!" }
default { say "你是誰?" }
}
部分匹配
# 你只關心某些感興趣的值，不關心其它值装哆，使用 `*` 號或 `$` 來代表 "any value is fine"
my $authentication = ("twostraws", "fr0st1es", "127.0.0.1");
given $authentication {
when ("bilbo", "bagg1n5", *) { say "Hello, Bilbo Baggins!"}
when ("twostraws", "fr0st1es", $) { say "Hello, Paul Hudson!" }
default { say "Who are you?" }
}
只匹配元組的一部分
# 但仍然想知道其它部分是什么
my $authentication = ("twostraws", "fr0st1es");
given $authentication {
when ("bilbo", *) { say "Hello, Bilbo Baggins!" }
when ("twostraws", *) { say "Hello, Paul Hudson: your password was $_!" }
default { say "Who are you?" }
}
匹配計算型元組
sub fizzbuzz(Int $number) returns Str {
given ($number % 3 == 0, $number % 5 == 0) {
when (True, False) { return "Fizz" }
when (False, True) { return "Buzz" }
when (True, True) { return "FizzBuzz" }
when (False, False) { return $number.Str}
}
}
say fizzbuzz(15);
遍歷元組
my $twostraws = ("twostraws", "fr0st1es");
my $bilbo = ("bilbo", "bagg1n5");
my $taylor = ("taylor", "fr0st1es");
my @users = $twostraws, $bilbo, $taylor;
for @users -> $user {
say $user[0];
}
使用 when 匹配元組中的指定值
my $twostraws = ("twostraws", "fr0st1es");
my $bilbo = ("bilbo", "bagg1n5");
my $taylor = ("taylor", "fr0st1es");
my @users = $twostraws, $bilbo, $taylor;
say "User twostraws has the password fr0st1es" when ("twostraws", "fr0st1es") for @users;
# 打印密碼為指定值的用戶
say "User $_[0] has password \"fr0st1es\"" when (*, "fr0st1es") for @users;
匹配范圍
my $age = 36;
given $age {
when 0 ..^ 18 { say "你有活力有時間萍桌，但是沒錢" }
when 18 ..^ 70 { say "你有活力有錢凌简，但是沒時間" }
default { say "你有時間和金錢，但是沒活力"}
}
when 可以配合智能匹配操作符 ~~ 單獨使用
my $age = 36;
when $age ~~ 0 ..^ 18 { say "你有活力有時間藕施，但是沒錢" }
when $age ~~ 18 ..^ 70 { say "你有活力有錢凸郑，但是沒時間" }
default { say "你有時間和金錢，但是沒活力"}
使用 contains 方法
my $age = 36;
when (0 ..^ 18).contains($age) { say "你有活力有時間胞谈，但是沒錢" }
when (18 ..^ 70).contains($age) { say "你有活力有錢，但是沒時間" }
default { say "你有時間和金錢，但是沒活力"}
匹配元組中的范圍
my $user = ("twostraws", "fr0st1es", 36);
given $user {
my $name = $user[0];
when ($name, *, 0 ..^ 18) { say "$name 有活力有時間配紫，但是沒錢" }
when ($name, *, 18 ..^ 70) { say "$name 有活力有錢躺孝，但是沒時間" }
when ($name, *, *) { say "$name 有時間和金錢,但是沒活力" }
}
枚舉
enum WeatherType <Cloudy Sunny Windy>;
my $today = WeatherType::Cloudy;
given $today {
when WeatherType::Cloudy { say "多云" }
when WeatherType::Sunny { say "晴天" }
when WeatherType::Windy { say "有風" }
}
# 使用 if 語句
if $today ~~ WeatherType::Cloudy { say "多云" }
關聯(lián)值
enum WeatherType (
Cloudy => 100,
Sunny => 50,
Windy => 30
);
my $today = WeatherType::Windy;
given $today {
when WeatherType::Cloudy { say 20*Cloudy }
when WeatherType::Sunny { say 10*Sunny }
when WeatherType::Windy { say 12*Windy }
}
when 從句
my @numbers = 1..10;
.say when $_ % 2 == 1 for @numbers;
my @celebrities = "Michael Jackson", "Taylor Swift", "MichaelCaine", "Adele Adkins", "Michael Jordan";
.say when /^Michael/ for @celebrities; # 使用正則表達式
.say when $_.chars > 12 for @celebrities; # 調(diào)用方法
.say when /^Michael/ and $_.chars >12 for @celebrities; # 復合條件
