[英]Implicit void return in PHP 7.1?
I found in here the new spec: https://wiki.php.net/rfc/void_return_type 我在这里找到了新的规范: https : //wiki.php.net/rfc/void_return_type
function lacks_return(): void {
// valid
}
function returns_nothing(): void {
return; // valid
}
function returns_void(): void {
return void; // valid
}
Ask: Do you know what happens behind the scene. 问:你知道幕后发生了什么。 Will the lacks_return
function return actually void
? lacks_return
函数返回实际上是否void
?
Behind the scenes, PHP checks for return
statements in void
functions and, if they specify a return value, throws a compile-time error: 在幕后,PHP 检查void
函数中的return
语句 ,如果它们指定了返回值,则抛出编译时错误:
/* `return ...;` is illegal in a void function (but `return;` isn't) */
if (return_info->type_hint == IS_VOID) {
if (expr) {
if (expr->op_type == IS_CONST && Z_TYPE(expr->u.constant) == IS_NULL) {
zend_error_noreturn(E_COMPILE_ERROR,
"A void function must not return a value "
"(did you mean \"return;\" instead of \"return null;\"?)");
} else {
zend_error_noreturn(E_COMPILE_ERROR, "A void function must not return a value");
}
}
/* we don't need run-time check */
return;
}
Otherwise, compilation of void
functions works like normal. 否则, void
函数的编译就像普通函数一样。 return
without a value implicitly returns NULL
: 没有值的return
隐式返回NULL
:
if (!expr_ast) {
expr_node.op_type = IS_CONST;
ZVAL_NULL(&expr_node.u.constant);
And every function is compiled with an implicit return
at the end : 并且每个函数都在最后使用隐式return
进行编译 :
zend_emit_final_return(0);
Whose return value is NULL
: 其返回值为NULL
:
zn.op_type = IS_CONST;
if (return_one) {
ZVAL_LONG(&zn.u.constant, 1);
} else {
ZVAL_NULL(&zn.u.constant);
}
You could have tested this yourself pretty easily: 你可以很容易地自己测试一下:
function lacks_return(): void {
}
function returns_nothing(): void {
return;
}
echo gettype(lacks_return()); // NULL
echo gettype(returns_nothing()); // NULL
So the answer is yes - there is an implicit empty (null) return so you could either use an empty return or skip it completely. 所以答案是肯定的 - 有一个隐式的空(null)返回,所以你可以使用空返回或完全跳过它。 Which kind of makes sense - returning nothing is the same as not returning anything? 哪种有意义 - 什么都不返回就像没有返回什么一样?
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