PHP 7+ 中的命名参数解决方案

Question

如何在 PHP 7+ 中实现命名参数功能？

理想的语法是：

find($wildcard, relative = true, listIfEmpty = false) {
    ...
}

但是没有这样的解决方案。在答案中，我实现了最短的解决方案，支持：

• 重构
• 参数和函数结果的类型提示
• 可重用参数集
• 类型安全参数
• 参数的默认值
• 每个参数的 Getter（无硬编码字符串）
• 非常简单的 setter/getter，您只需为每个参数更改一个名称

有关更多信息和实施，请参阅答案

Answer 1

首先，在您的框架中或全局执行一次：

// the superclass that every params class will extend this
class params {
  protected function setter($key, $value) {
    if ($value === null) {
      return $this->{$key};
    }

    $this->{$key} = $value;
    return $this;
  }
}

然后，对每个需要具有正确名称的命名参数的函数执行此操作：

// define a helper method for simple instantiation
function params_find() { return new params_find(); }

// a params class that will use from find() method
class params_find extends params {

  // list of params with default values
  // below list is just a sample
  protected $listIfEmpty   = false;
  protected $structured    = true;
  protected $relative      = false;
  protected $prefix        = "";
  protected $justFileNames = false;

  // for each param duplicate line and just change function name exactly matching param name. setter/getter will done automatically
  function listIfEmpty($val = null)   { return $this->setter(__FUNCTION__, $val); }
  function structured($val = null)    { return $this->setter(__FUNCTION__, $val); }
  function relative($val = null)      { return $this->setter(__FUNCTION__, $val); }
  function prefix($val = null)        { return $this->setter(__FUNCTION__, $val); }
  function justFileNames($val = null) { return $this->setter(__FUNCTION__, $val); }
}

之后，使用此功能编写您的函数：

// your function that uses named arguments
// in this example $wildcard argument is required
function find($wildcard = [], params_find $opt = null) {
  if ($opt === null) {
    $opt = params_find();
  }

  // do something with your params like this
  if ($opt->structured()) {
    // ...
  }

  return $something_if_you_want;
}

最后用最简单的接口来使用：

// finally use your function with some params ( other params will have default values )
$files = find("*.css", params_find()
  ->structured(false)
  ->listIfEmpty(true)
  ->prefix("something")
);


// if you need all default values
$files = find("*.css");


// reusable options
$opt = params_find()
  ->listIfEmpty(false)
  ->prefix("something")
)
$files1 = find("*.css", $opt);
$files2 = find("*.html", $opt);
$files3 = find("*.scss", $opt
  ->structured(true)
);