dqwh1208 2017-05-04 19:13
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Php - 函数和变量是否必须公开?

Do functions and variables have to be declared public or are they public by default?

Class Bread {
    $bread = "";    
    function toast()
    {
        $bread = "Toasticles!"
    }
}

In this example, is both $bread and the function toast() public without actually declaring them as such?

This is a question about instance variables and function visibility

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  • douzhi3586 2017-05-04 19:24
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    If you declare $bread without visibility, you will get a parse error:

    Parse error: syntax error, unexpected '$bread' (T_VARIABLE), expecting function (T_FUNCTION) or const (T_CONST) in [...][...] on line x

    This is because, as @darkcrystale also mentioned and as PHP documentation states, class properties must be defined as public, private, or protected. If declared using var, the property will be defined as public.

    Function toast() will be public by default if you do not specify the visibility explicitly.

    But please keep in mind, that doing things explicitly is better, than doing things implicitly. Thus, declaring visibility as public in every case might help those, who read your code after you. If you don't care about those, who might work with your code (btw shame on you in that case), think of another example: you write a lot of code not declaring visibility explicitly and it's public at that time. But if the PHP devs go crazy and change default visibility to private, then most of your code becomes useless (and will not work) for obvious reasons.

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