如果多个Trait中包含同名方法或者属性时,会怎样呢?答案是当组合的多个Trait包含同名属性或者方法时,需要明确声明解决冲突,否则会产生一个致命错误。
<?php trait Trait1 { public function hello() { echo "Trait1::hello\n"; } public function hi() { echo "Trait1::hi\n"; } } trait Trait2 { public function hello() { echo "Trait2::hello\n"; } public function hi() { echo "Trait2::hi\n"; } } class Class1 { use Trait1, Trait2; } //输出:Fatal error: Trait method hello has not been applied, because there are collisions with other trait methods on Class1 in
使用insteadof和as操作符来解决冲突,insteadof是使用某个方法替代另一个,而as是给方法取一个别名,具体用法请看代码:
<?php trait Trait1 { public function hello() { echo "Trait1::hello \n"; } public function hi() { echo "Trait1::hi \n"; } } trait Trait2 { public function hello() { echo "Trait2::hello\n"; } public function hi() { echo "Trait2::hi\n"; } } class Class1 { use Trait1, Trait2 { Trait2::hello insteadof Trait1; Trait1::hi insteadof Trait2; } } class Class2 { use Trait1, Trait2 { Trait2::hello insteadof Trait1; Trait1::hi insteadof Trait2; Trait2::hi as hei; Trait1::hello as hehe; } } $Obj1 = new Class1(); $Obj1->hello(); $Obj1->hi(); echo "\n"; $Obj2 = new Class2(); $Obj2->hello(); $Obj2->hi(); $Obj2->hei(); $Obj2->hehe();
输出结果:
Trait2::hello Trait1::hi Trait2::hello Trait1::hi Trait2::hi Trait1::hello