PHP Sort函数用于对对象数组进行排序 [英] PHP Sort function for sorting an array of objects

问题描述

我有一个数组，里面装满了来自同一类的对象.我想按可选对象字段(例如$case->ID或$case->Sender

I have an array full of objects from the same class. I'd like to sort this array by optional object field, for instance $case->ID or $case->Sender

是否已经内置了array_sort()函数，或者我必须自己编写此sort函数?

Is there a built in flavor of the array_sort() function that does this already, or will I have to write this sort function myself?

答案不必详细解释-这更像是是/否问题

Answer doesn't have to explain in detail - this is more like a yes/no question

谢谢

我对usort的尝试失败:

My failed attempt at usort:

function sortBy($sort)
  {
   usort($this->abuseCases, function($a, $b) {
     if($a->{$sort} > $b->{$sort}) return 1;
     if($a->{$sort} < $b->{$sort}) return -1;
     else return 0;
    });
  }

---

另一次失败的尝试:

---

Another failed attempt:

    function sortBy($sort)
    {
        $this->sortBy = $sort;

        usort($this->abuseCases, array("this", "srt"));
    }

    private function srt($a, $b)
    {
        if($a->{$this->sortBy} > $b->{$this->sortBy}) return 1;
        if($a->{$this->sortBy} < $b->{$this->sortBy}) return -1;
        else return 0;
    }

---

编辑凹凸

---

Edit for bump

推荐答案

您不仅可以使用匿名函数，还可以使用闭包，例如

You can use not only an anonymous function but a closure, like e.g.

function ($a,$b) use ($sort) { ... }

和$ sort将在功能主体中可用. 独立的示例:

and $sort will be available in the function body. Self-contained example:

<?php
function getFn($sort) {
  return function($a, $b) use($sort) {
    if($a->$sort > $b->$sort) return 1;
    if($a->$sort < $b->$sort) return -1;
    return 0;
  };
}

$abuseCases = array(
  (object)array('ID'=>1, 'Sender'=>'Sender A'),
  (object)array('ID'=>3, 'Sender'=>'Sender D'),
  (object)array('ID'=>2, 'Sender'=>'Sender C'),
  (object)array('ID'=>4, 'Sender'=>'Sender B')
);

echo "\n----- Sort By Sender ----\n";
usort($abuseCases, getFn('Sender'));
foo($abuseCases);

echo "\n----- Sort By ID ----\n";
usort($abuseCases, getFn('ID'));
foo($abuseCases);

function foo($a) {
  foreach($a as $o) {
    echo $o->ID, ' ', $o->Sender, "\n";
  }
}

打印

----- Sort By Sender ----
1 Sender A
4 Sender B
2 Sender C
3 Sender D

----- Sort By ID ----
1 Sender A
2 Sender C
3 Sender D
4 Sender B

---

更新:通过php< 5.3，您可以使用对象而不是匿名函数. usort()期望第二个参数为callable.自php 5.3起，这可能是一个异常的函数，但也可能是函数的名称....或作为数组(如array($obj, 'methodName'))传递的对象和方法名称.

---

Update: With php<5.3 you can use an object instead of an anonymous function. usort() expects the second parameter to be a callable. That can be an anoymous function as of php 5.3, but it can also be the name of a function ....or an object and a method name passed as an array like array($obj, 'methodName').

$abuseCases = getData();
echo "\n----- Sort By Sender ----\n";
usort($abuseCases, array(new Foo('Sender'), 'compare'));
foo($abuseCases);

echo "\n----- Sort By ID ----\n";
usort($abuseCases, array(new Foo('ID'), 'compare'));
foo($abuseCases);

class Foo {
  public $propName; // protected?
  public function __construct($propertyName) {
    $this->propName = $propertyName;
  }
  public function compare($a, $b) {
    $prop = $this->propName;
    if($a->$prop > $b->$prop) return 1;
    if($a->$prop < $b->$prop) return -1;
    return 0;
  }
}

function foo($a) {
  foreach($a as $o) {
    echo $o->ID, ' ', $o->Sender, "\n";
  }
}
function getData() {
  return array(
    (object)array('ID'=>1, 'Sender'=>'Sender A'),
    (object)array('ID'=>3, 'Sender'=>'Sender D'),
    (object)array('ID'=>2, 'Sender'=>'Sender C'),
    (object)array('ID'=>4, 'Sender'=>'Sender B')
  );
}

(如果您大量使用这个-或不想写这样的借口-_--您可能想定义一个像interface Comparator { ... }这样的接口，让Foo实现该接口并具有一些函数/类使用Comparator，即usort()周围对象的包装器.)

(If you make heavy use of this - or don't want to write excuses like this one -_- - you might want to define an interface like interface Comparator { ... }, let Foo implement that interface and have some function/class that uses Comparator, i.e. a wrapper for objects around usort().)

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