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Section 10.9.  Packages and Lexicals

 
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10.9. Packages and Lexicals

A lexical variable (a variable introduced with my) isn't prefixed by the current package because package variables are always global: we can always reference a package variable if we know its full name. A lexical variable is usually temporary and accessible for only a portion of the program. If we declare a lexical variable, then using that name without a package prefix gets the lexical variable. A package prefix ensures that we are accessing a package variable and never a lexical variable.

For example, suppose a subroutine within navigation.pm declares a lexical @homeport variable. Any mention of @homeport will then be the newly introduced lexical variable, but a fully qualified mention of @Navigation::homeport accesses the package variable instead.

package Navigation;
@homeport = (21.283, -157.842);

sub get_me_home {
  my @homeport;

  .. @homeport .. # refers to the lexical variable
  .. @Navigation::homeport .. # refers to the package variable

}

.. @homeport .. # refers to the package variable

Obviously, this can lead to confusing code, so we shouldn't introduce such duplication needlessly. The results are completely predictable, though.


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