Calling a function using the -> syntax calls it as an object method.
Nope. -> has a double purpose:
  1. Object method call: $obj->meth(@params)
  2. Class method call: Class->meth(@params)
What the OP did, is applying the latter: invoking a function intended to be used as a function, as a class method. The result is that an extra parameter is unshifted, by perl, in the argument list, @_, before control is passed to it: the Class, which is a string.

He should try, with a higher chance of success, to call 

Date::Calc::Add_Delta_Days($year,$month,$day, -3);

[download]

In reply to Re: Re: Perl module symbol import versus direct invocation by bart
in thread Perl module symbol import versus direct invocation by JayBonci

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