php-doc-en/reference/com/functions/class.variant.xml

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<refentry xml:id="class.variant" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>VARIANT</refname>
  <refpurpose>VARIANT class</refpurpose>
 </refnamediv>
 <refsynopsisdiv>
 <synopsis>$vVar = new <classname>VARIANT</classname>($var)</synopsis>
 </refsynopsisdiv>
 <refsect1 xml:id="class.variant.class">
  <title>Description</title>
  <simpara>
   The VARIANT is COM's equivalent of the PHP zval; it is a structure that
   can contain a value with a range of different possible types.  The VARIANT
   class provided by the COM extension allows you to have more control over
   the way that PHP passes values to and from COM.
  </simpara>
 </refsect1>
 <refsect1 xml:id="class.variant.constructor">
  <title>Methods</title>
  <methodsynopsis>
   <type>object</type><methodname>VARIANT::VARIANT</methodname>
   <methodparam choice="opt"><type>mixed</type><parameter>value</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>type</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>codepage</parameter></methodparam>
  </methodsynopsis>
  <para>
   VARIANT class constructor. Parameters:
   <variablelist>
   <varlistentry><term>value</term>
   <listitem>
    <simpara>
     initial value. if omitted, or set to &null; an VT_EMPTY object is created.
    </simpara>
   </listitem>
   </varlistentry>
   <varlistentry><term>type</term>
   <listitem>
    <simpara>
     specifies the content type of the VARIANT object. Possible values are
     one of the <constant>VT_XXX</constant> <xref
     linkend="com.constants"/>.
    </simpara>
    <simpara>
     In PHP versions prior to PHP 5, you could force PHP to pass a variant
     object by reference by OR'ing <constant>VT_BYREF</constant>
     with the <parameter>type</parameter>.  In PHP 5, this hack is not
     supported; instead, PHP 5 can detect parameters passed by reference
     automatically; they do not even need to be passed as VARIANT objects.
    </simpara>
    <simpara>
     Consult the <acronym>MSDN</acronym> library for additional information
     on the VARIANT type.
    </simpara>
   </listitem>
   </varlistentry>
   <varlistentry><term>codepage</term>
   <listitem>
    <simpara>
     specifies the codepage that is used to convert strings to
     unicode.  See the parameter of the same name in the
     <xref linkend="class.com"/> class for more information.
    </simpara>
   </listitem>
   </varlistentry>
   </variablelist>
  </para>
  <para>
   PHP versions prior to PHP 5 define a number of (undocumented) virtual properties
   for instances of the VARIANT class; these properties have all been removed in
   PHP 5 in favour of its more natural syntax; these differences are best
   highlighted by example:
  </para>
  <para>
   <example xml:id="com.variant.example.php4">
    <title>Variant example, PHP 4.x style</title>
    <programlisting role="php">
<![CDATA[
<?php
$v = new VARIANT(42);
print "The type is " . $v->type . "<br/>";
print "The value is " . $v->value . "<br/>";
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example xml:id="com.variant.example.php5">
    <title>Variant example, PHP 5 style</title>
    <programlisting role="php">
<![CDATA[
<?php
$v = new VARIANT(42);
print "The type is " . variant_get_type($v) . "<br/>";
print "The value is " . $v . "<br/>";
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   The reason for the change is that, internally, the COM extension sees
   VARIANT, COM and DOTNET classes as the same thing, and the design
   philosophy for these classes is that all property and member accesses are
   passed through to COM with no interference.  The new syntax is more
   natural and less effort, and most of the removed virtual properties didn't
   make any sense in a PHP context in any case.
  </para>
  <note>
   <para>
    PHP 5 takes a much simpler approach to handling VARIANTs; when returning
    a value or fetching a variant property, the variant is converted to a PHP
    value only when there is a direct mapping between the types that would
    not result in a loss of information.  In all other cases, the result is
    returned as an instance of the VARIANT class.  You can force PHP to
    convert or evaluate the variant as a PHP native type by using a casting
    operator explicitly, or implicitly casting to a string by
    <function>print</function>ing it.  You may use the wide range of variant
    functions to perform arithmetic operations on variants without forcing a
    conversion or risking a loss of data.
   </para>
  </note>
  <para>
   See also <function>variant_get_type</function>.
  </para>
 </refsect1>
</refentry>

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