2.9. Packages and LexicalsA lexical variable (a variable introduced with my) isn't prefixed by the current package because package variables are always global: you can always reference a package variable if you know its full name. A lexical variable is usually temporary and accessible for only a portion of the program. If a lexical variable is declared, then using that name without a package prefix results in accessing the lexical variable. However, a package prefix ensures that you are accessing a package variable and never a lexical variable. For example, suppose a subroutine within navigation.pl 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 = (21.1, -157.525); 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 you shouldn't introduce such a duplication needlessly. The results are completely predictable, though. Copyright © 2003 O'Reilly & Associates. All rights reserved. |
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