FAQ 7.19 What's the difference between deep and shallow binding?


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7.19: What's the difference between deep and shallow binding?

In deep binding, lexical variables mentioned in anonymous subroutines
are the same ones that were in scope when the subroutine was created. In
shallow binding, they are whichever variables with the same names happen
to be in scope when the subroutine is called. Perl always uses deep
binding of lexical variables (i.e., those created with my()). However,
dynamic variables (aka global, local, or package variables) are
effectively shallowly bound. Consider this just one more reason not to
use them. See the answer to "What's a closure?".


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