不能在类中调用PHP的date（）？ [重复]

Question

This question already has an answer here:

• declare property as object? 4 answers

I get an error when I use date() when initializing an instance variable

class User extends Connectable {
    private $date = date('Y-m-d');
}

The error is

 Parse error: syntax error, unexpected '(', expecting ',' or ';' 

This is weird, because it works fine when I call date() from inside a function, or outside the class...

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Answer 1

The properties declaration may include an initialization, but this initialization must be a constant value, that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

You could initialize it in the constructor method.