PHP 5.4 introduced a technique called traits. This technique aims to provide code re-usability functionality similar to mixins in other programming languages. The most common use case is to reuse methods among different classes.
Here is an example of the syntax;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
trait someMath
{
function add($a, $b)
{
return $a + $b;
}
function multiply($a, $b)
{
return $a * $b;
}
}
class Calculator
{
use someMath;
}
$cal = new Calculator();
echo $cal->add(4, 6); // echoes 10
As you can see traits syntax is very similar to the syntax to create a class. We just need to change the keyword class for trait. Then we can apply the trait inside a class using the use keyword.
Precedence
Method collisions are resolved in this order of precedence:
- Defined on the class
- Defined on trait
- Defined on parent class
The topmost in the list is the method that will be used when called from an instance. Lets see an example:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
trait someMath
{
function add($a, $b)
{
return $a + $b;
}
function multiply($a, $b)
{
return $a * $b;
}
}
class Calculator
{
function subtract($a, $b)
{
return $a - $b;
}
function multiply($a, $b)
{
return $a * $b * 100;
}
}
class BrokenCalculator extends Calculator
{
use someMath;
function add($a, $b)
{
return 9;
}
}
$cal = new BrokenCalculator();
echo $cal->add(4, 6); // echoes 9
echo $cal->multiply(2, 2); // echoes 4
echo $cal->subtract(5, 3); // echoes 2
You can do a lot more cool things with traits, but there is no use on duplicating what is already well documented. You can see more use cases here: PHP Manual: Traits
design_patterns php programming