在PHP中有条件地使用特征

I want to use a trait in a class, only if a condition is satisfied. For example:

trait T
{
}
class A
{
    if ($condition) {
        use T;
    }
}

I know I can't use if directly in class. So, I'm looking for a way to use traits conditionally similar to the above. Is it possible?

You can create a class with use T which extends the class without use T. And then in your code where you use the class do an if and instanciate the one or the other class.

<?php

trait T {
}

class A {
}

class B extends A {
    use T;
}

// In an other part of code
$obj = null;

if($condition) {
    $obj = new B();
} else {
    $obj = new A();
}

/* EOF */

trait T {
function getType() { 
     if($condition){ /*somthing*/ 
          }else{ 
           throw new Exception('some thing.') 
        } }
function getDescription() { /*2*/ }
}
class A {
use T;
/* ... */
}

You can outsource your conditional code (like debug-functions) in a trait and do something like that.

//your Trait

if($isModeDbg){
    trait Dbg{
        function dbg(mssg){
            debugbarOrSomethingSimilar(mssg);
        }
    }
}else{
    trait Dbg{
        function dbg(mssg){
        }
    }
}

//your class
class Something{
  use Dbg;
}