Parsing and normalization of input, combined with output to localized notations makes data
accessible to users in different locales. Many additional methods exist in
Zend_Measure_* components to manipulate and work with this data,
after it has been normalized.
Probably the most important feature is the conversion into different units of
measurement. The conversion of a unit can be done any number of times using the method
convertTo(). Units of measurement can only be converted to
other units of the same type (class). Therefore, it is not possible to convert (e.g.) a
length into a weight, which would might encourage poor programming practices and allow
errors to propagate without exceptions.
The convertTo() method accepts an optional parameter. With
this parameter you can define an precision for the returned output. The standard
precision is '2'.
Example #1 Convert
$locale = new Zend_Locale('de');
$mystring = "1.234.567,89";
$unit = new Zend_Measure_Weight($mystring,'POND', $locale);
Measurements can be added together using add() and subtracted
using sub(). The result will use the same type as the
originating object. Dynamic objects support a fluid style of programming, where complex
sequences of operations can be nested without risk of side-effects altering the input
objects.
Example #2 Adding units
// Define objects
$unit = new Zend_Measure_Length(200, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
Note: Automatic conversion
Adding one object to another will automatically convert it to the correct unit. It
is not necessary to call convertTo()
before adding different units.
Example #3 Subtract
Subtraction of measurements works just like addition.
// Define objects
$unit = new Zend_Measure_Length(200, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
Measurements can also be compared, but without automatic unit conversion. Thus,
equals() returns TRUE, only if both the
value and the unit of measure are identical.
Example #4 Different measurements
// Define measurements
$unit = new Zend_Measure_Length(100, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
To determine if a measurement is less than or greater than another, use
compare(), which returns 0, -1 or 1 depending on the difference
between the two objects. Identical measurements will return 0. Lesser ones will return a
negative, greater ones a positive value.
Example #6 Difference
$unit = new Zend_Measure_Length(100, Zend_Measure_Length::CENTIMETER);
$unit2 = new Zend_Measure_Length(1, Zend_Measure_Length::METER);
$unit3 = new Zend_Measure_Length(1.2, Zend_Measure_Length::METER);