Manual:

Reference:

-- Perl 5.8.7 documentation --

if - use a Perl module if a condition holds

  use if CONDITION, MODULE => ARGUMENTS;

The construct

  use if CONDITION, MODULE => ARGUMENTS;

has no effect unless CONDITION is true. In this case the effect is the same as of

  use MODULE ARGUMENTS;

The current implementation does not allow specification of the required version of the module.