What instructions must I include in my program to be able to use clases that derive from superclases contained in separate files. In other words, if class B is a subclass of class A, but the former is in the file b.php and the latter in a.php, which steps must I take so that class B inside "b.php" can be a subclass of class A in "a.php"?
Additionally I would like to know whether PHP has built-in mechanisms to prevent including a file more than once in a multiple file app, in which more than one file might require a given common file. Thanks in advance.
Additionally I would like to know whether PHP has built-in mechanisms to prevent including a file more than once in a multiple file app, in which more than one file might require a given common file. Thanks in advance.
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