php 中函数获取可变参数的方法， 这个语法有点像 golang 语言中的

<?php

function a(bool $value){

    var_dump($value);

}

a(true);

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1. php函数调用中获取变长参数的方法， ...token ,类似于golang语言中的。

2. php 中也有类似与javascript 中的 "use strict ";严格模式。

Strict typing¶

By default, PHP will coerce values of the wrong type into the expected scalar type if possible. For example, a function that is given an integer for a parameter that expects a string will get a variable of type string.

It is possible to enable strict mode on a per-file basis. In strict mode, only a variable of exact type of the type declaration will be accepted, or a TypeError will be thrown. The only exception to this rule is that an integer may be given to a function expecting a float. Function calls from within internal functions will not be affected by the strict_types declaration.

To enable strict mode, the declare statement is used with the strict_types declaration:

<?php

declare(strict_types=1);

function sum(int $a, int $b) {

    return $a + $b;

}

var_dump(sum(1, 2));

var_dump(sum(1.5, 2.5));

?>

　　3.Type declarations¶

Note:

Type declarations were also known as type hints in PHP 5.

Type declarations allow functions to require that parameters are of a certain type at call time. If the given value is of the incorrect type, then an error is generated: in PHP 5, this will be a recoverable fatal error, while PHP 7 will throw a TypeError exception.

NULLNULL

Warning

Aliases for the above scalar types are not supported(意思是： 只能用int, 而不能用integer, 只能用bool,不能用boolean.). Instead, they are treated as class or interface names. For example, using boolean as a parameter or return type will require an argument or return value that is an instanceof the class or interface boolean, rather than of type bool:

 Fatal error: Uncaught TypeError: Argument 1 passed to test() must be an instance of boolean, boolean given, called in - on line 1 and defined in -:1
 

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... in PHP 5.6+¶

In PHP 5.6 and later, argument lists may include the ... token to denote that the function accepts a variable number of arguments. The arguments will be passed into the given variable as an array; for example:

10

You can also use ... when calling functions to unpack an array or Traversable variable or literal into the argument list:

3

3

You may specify normal positional arguments before the ... token. In this case, only the trailing arguments that don't match a positional argument will be added to the array generated by ....

It is also possible to add a type hint before the ... token. If this is present, then all arguments captured by ... must be objects of the hinted class.

3 days

Catchable fatal error: Argument 2 passed to total_intervals() must be an instance of DateInterval, null given, called in - on line 14 and defined in - on line 2

Finally, you may also pass variable arguments by reference by prefixing the ... with an ampersand (&).