Brainstorming for sequence handling split based on element criteria

Test.class.php

<?php
use util\data\Sequence;

class Types extends \lang\Enum {
  public static $OPEN, $CLOSED;
}

class Wall extends \lang\Object {
  private $name, $type;

  public function __construct($name, Types $type) {
    $this->name= $name;
    $this->type= $type;
  }

  public function name() { return $this->name; }
  public function type() { return $this->type; }
}

class Test extends \lang\Object {

  static function __static() { Types::__static(); }

  public static function main($args) {
    Sequence::of([new Wall('My Team', Types::$CLOSED), new Wall('Developers', Types::$OPEN)])
      ->map(function($wall) {
        if (Types::$OPEN === $wall->type()) {
          return 'Open walls like '.$wall->name().' are great';
        } else {
          return 'Closed walls make sense sometimes, e.g. for '.$wall->name();
        }
      })
      ->each('util.cmd.Console::writeLine')
    ;
  }
}

The Problem

I don't like the if statement.

Side note: The line static function __static() { Types::__static(); } is necessary as we're using inline-declared classes Types and Wall that the classloader doesn't really know about.

Idea #1

Introduce a match / when mini-DSL:

Sequence::of([new Wall('My Team', Types::$CLOSED), new Wall('Developers', Types::$OPEN)])
  ->map((new Match('Wall::type'))
    ->when(Types::$OPEN, function($wall) { return 'Open walls like '.$wall->name().' are great'; })
    ->when(Types::$CLOSED, function($wall) { return 'Closed walls make sense sometimes, e.g. for '.$wall->name(); })
  )
  ->each('util.cmd.Console::writeLine')
;

• ✅ Reads well
• ✅ Default handling of unhandled values = fail early
• ✅ Would be extensible with other criteria, e.g. using something like isEqualTo and isInstanceOf methods instead of when.
• ◻️ Performance worse than if - could be mitigated by using map backing for enum usecase

See https://github.com/xp-forge/match for the API itself and the performance figures