[sf-perl] oddity with an exported and localized variable
eruby at knowledgematters.net
Mon Nov 30 12:41:12 PST 2009
2009/11/26 yary <not.com at gmail.com>:
> Based on the perlsub section "Temporary Values via local()":
> A "local" modifies its listed variables to be "local" to the
> block, "eval", or "do FILE"--and to any subroutine called from within
> that block. A "local" just gives temporary values to global (meaning
> package) variables. It does not create a local variable. This is
> known as dynamic scoping. ...
> Emphasis is in the original perldoc. So it looks like a bug to me too. Bring
> it to the monks.
Maybe I'm missing something here, but for the localized variable,
doesn't "the enclosing block and any subroutine called from within
that block" include all of the print statements after the local
declaration and the check_value_local_def sub?
For the "our" variables in the module
"our associates a simple name with a package variable in the current
package for use within the current scope. When use strict 'vars' is
in effect, our lets you use declared global variables without
qualifying them with package names, within the lexical scope of the
our declaration. In this way our differs from use vars , which is
"Unlike my, which both allocates storage for a variable and associates
a simple name with that storage for use within the current scope, our
associates a simple name with a package variable in the current
package, for use within the current scope. In other words, our has the
same scoping rules as my, but does not necessarily create a variable."
FWIW, output is the same under Perl 5.8.8 as 5.10.0:
initial value: initial
the new value: new value
exported_variable: new value
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are, by
definition, not smart enough to debug it. " -- Brian Kernighan
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