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<refentry xml:id="ds-map.put" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>Ds\Map::put</refname>
  <refpurpose>Associates a key with a value</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <modifier>public</modifier> <type>void</type><methodname>Ds\Map::put</methodname>
   <methodparam><type>mixed</type><parameter>key</parameter></methodparam>
   <methodparam><type>mixed</type><parameter>value</parameter></methodparam>
  </methodsynopsis>
  <para>
    Associates a <parameter>key</parameter> with a <parameter>value</parameter>,
    overwriting a previous association if one exists.
  </para>

  <note>
    <para>
        Keys of type <type>object</type> are supported.

        If an object implements <classname>Ds\Hashable</classname>,
        equality will be determined by the object's <code>equals</code> function.

        If an object does not implement <classname>Ds\Hashable</classname>,
        objects must be references to the same instance to be considered equal.
    </para>
  </note>

  <note>
    <para>
        You can also use array syntax to associate values by key, eg. <code>$map["key"] = $value</code>.
    </para>
  </note>

  <caution>
    <para>
        Be careful when using array syntax. Scalar keys will be coerced to
        integers by the engine. For example, <code>$map["1"]</code> will attempt
        to access <code>int(1)</code>, while <code>$map-&gt;get("1")</code> will
        correctly look up the string key.
    </para>
    <para>
        See <link linkend="language.types.array">Arrays</link>.
    </para>
  </caution>

 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>key</parameter></term>
    <listitem>
     <para>
        The key to associate the value with.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>value</parameter></term>
    <listitem>
     <para>
        The value to be associated with the key.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
    &return.void;
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>Ds\Map::put</function> example</title>
   <programlisting role="php">
<![CDATA[
<?php
$map = new \Ds\Map();

$map->put("a", 1);
$map->put("b", 2);
$map->put("c", 3);

print_r($map);
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 1
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 2
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 3
        )

)
]]>
   </screen>
  </example>
  <example>
   <title><function>Ds\Map::put</function> example using objects as keys</title>
   <programlisting role="php">
<![CDATA[
<?php
class HashableObject implements \Ds\Hashable
{
    /**
     * An arbitrary value to use as the hash value. Does not define equality.
     */
    private $value;

    public function __construct($value)
    {
        $this->value = $value;
    }

    public function hash()
    {
        return $this->value;
    }

    public function equals($obj): bool
    {
        return $this->value === $obj->value;
    }
}

$map = new \Ds\Map();

$obj = new \ArrayIterator([]);

// Using the same instance multiple times will overwrite the previous value.
$map->put($obj, 1);
$map->put($obj, 2);

// Using multiple instances of the same object will create new associations.
$map->put(new \stdClass(), 3);
$map->put(new \stdClass(), 4);

// Using multiple instances of equal hashable objects will overwrite previous values.
$map->put(new \HashableObject(1), 5);
$map->put(new \HashableObject(1), 6);
$map->put(new \HashableObject(2), 7);
$map->put(new \HashableObject(2), 8);

var_dump($map);
?>
]]>
   </programlisting>
   &example.outputs.similar;
   <screen>
<![CDATA[
object(Ds\Map)#1 (5) {
  [0]=>
  object(Ds\Pair)#7 (2) {
    ["key"]=>
    object(ArrayIterator)#2 (1) {
      ["storage":"ArrayIterator":private]=>
      array(0) {
      }
    }
    ["value"]=>
    int(2)
  }
  [1]=>
  object(Ds\Pair)#8 (2) {
    ["key"]=>
    object(stdClass)#3 (0) {
    }
    ["value"]=>
    int(3)
  }
  [2]=>
  object(Ds\Pair)#9 (2) {
    ["key"]=>
    object(stdClass)#4 (0) {
    }
    ["value"]=>
    int(4)
  }
  [3]=>
  object(Ds\Pair)#10 (2) {
    ["key"]=>
    object(HashableObject)#5 (1) {
      ["value":"HashableObject":private]=>
      int(1)
    }
    ["value"]=>
    int(6)
  }
  [4]=>
  object(Ds\Pair)#11 (2) {
    ["key"]=>
    object(HashableObject)#6 (1) {
      ["value":"HashableObject":private]=>
      int(2)
    }
    ["value"]=>
    int(8)
  }
}
]]>
   </screen>
  </example>
 </refsect1>


</refentry>

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