A property defined by a getter without a setter is *read only*. Trying to assign a value to such property will cause
A property defined by a getter without a setter is *read only*. Trying to assign a value to such a property will cause
an [[yii\base\InvalidCallException|InvalidCallException]]. Similarly, a property defined by a setter without a getter
an [[yii\base\InvalidCallException|InvalidCallException]]. Similarly, a property defined by a setter without a getter
is *write only*, and trying to read such property will also cause an exception. It is not common to have write-only
is *write only*, and trying to read such a property will also cause an exception. It is not common to have write-only
properties.
properties.
There are several special rules for, and limitations on, the properties defined via getters and setters:
There are several special rules for, and limitations on, the properties defined via getters and setters:
* The names of such properties are *case-insensitive*. For example, `$object->label` and `$object->Label` are the same.
* The names of such properties are *case-insensitive*. For example, `$object->label` and `$object->Label` are the same.
This is because method names in PHP are case-insensitive.
This is because method names in PHP are case-insensitive.
* If the name of such property is the same as a class member variable, the latter will take precedence.
* If the name of such a property is the same as a class member variable, the latter will take precedence.
For example, if the above `Foo` class has a member variable `label`, then the assignment `$object->label = 'abc'`
For example, if the above `Foo` class has a member variable `label`, then the assignment `$object->label = 'abc'`
will affect the *member variable* 'label'; that line would not call the `setLabel()` setter method.
will affect the *member variable* 'label'; that line would not call the `setLabel()` setter method.
* These properties do not support visibility. It makes no difference for the visibility of a property
* These properties do not support visibility. It makes no difference to the defining getter or setter method if the property is public, protected or private.
if the defining getter or setter method is public, protected or private.
* The properties can only be defined by *non-static* getters and/or setters. Static methods will not be treated in the same manner.
* The properties can only be defined by *non-static* getters and/or setters. Static methods will not be treated in the same manner.
Returning back to the problem described at the beginning of this guide, instead of calling `trim()` everywhere a `label` value is assigned, `trim()` now only needs to be invoked within the setter `setLabel()`. And if a new requirement comes that requires the label to be initially capitalized, the `setLabel()` method can quickly be modified without touching any other code. The one change will universally affect every assignment to `label`.
Returning back to the problem described at the beginning of this guide, instead of calling `trim()` everywhere a `label` value is assigned, `trim()` now only needs to be invoked within the setter `setLabel()`. And if a new requirement makes it necesary that the label be initially capitalized, the `setLabel()` method can quickly be modified without touching any other code. The one change will universally affect every assignment to `label`.
