VARIANT class

(PHP 4 >= 4.1.0, PHP 5)

Description

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.

$vVar = new VARIANT($var)

Methods

VARIANT::VARIANT ([ mixed $value [, int $type [, int $codepage ]]] )

VARIANT class constructor. Parameters:

value: initial value. if omitted, or set to NULL an VT_EMPTY object is created.
type: specifies the content type of the VARIANT object. Possible values are one of the VT_XXX 预定义常量. In PHP versions prior to PHP 5, you could force PHP to pass a variant object by reference by OR'ing VT_BYREF with the type. 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. Consult the MSDN library for additional information on the VARIANT type.
codepage: specifies the codepage that is used to convert strings to unicode. See the parameter of the same name in the COM class for more information.

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:

Example #1 Variant example, PHP 4.x style


<?php
$v = new VARIANT(42);
print "The type is " . $v->type . "<br/>";
print "The value is " . $v->value . "<br/>";
?>

Example #2 Variant example, PHP 5 style


<?php
$v = new VARIANT(42);
print "The type is " . variant_get_type($v) . "<br/>";
print "The value is " . $v . "<br/>";
?>

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.

Note:
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 printing 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.