Prototypes do nothing on method calls. There is plenty of talk about this in various forums. So they do not affect good users.

If someone tries to call UNIVERSAL::isa(...) with arguments (what use would it be otherwise) they will get the compile time error.

For example, this: 

> perl -e 'sub method() { }; main->method(1, 2, 3);'

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works, but this: 
> perl -e 'sub method() { }; main::method("main", 1, 2, 3);'
Too many arguments for main::method at -e line 1, near "3)"
Execution of -e aborted due to compilation errors.

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does not.

In reply to Re^2: Good use for prototypes. On methods no less! by polymorpheus
in thread Good use for prototypes. On methods no less! by polymorpheus

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