Named Parameters solution in PHP 7+

问题

How can I implement the named argument feature in PHP 7+?

The ideal syntax is:

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

But there is no solution to do like that. In the answer, I implemented the shortest possible solution that supports:

Refactoring
Type Hints for the params and function result
Reusable param set
Typesafe params
Default values for params
Getter for each param ( no hard-coded string )
Very simple setter/getter that you need to change just one name for every param

See the answer for more information and implementation

回答1:

Do it one in your Framework or globally:

// 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;
  }
}

Do it for each function that required named arguments with proper names:

// 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); }
}

Write your function using this feature:

// 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;
}

Finally, use it with the simplest interface:

// 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)
);

来源：https://stackoverflow.com/questions/56415163/named-parameters-solution-in-php-7

标签

php

parameter-passing

php-7

named-parameters