Some languages, like Perl and Common Lisp, allow the programmer to choose static or dynamic scoping when defining or redefining a variable.
Examples of languages that use dynamic scoping include Logo, Emacs lisp, and the shell languages bash, dash, and the MirBSD Korn shell (mksh)'s "local" declaration.
In contrast, call by reference and call by name semantics allow the parameters to act as aliases of the values passed as arguments, allowing the subroutine to modify variables outside its own scope.
In this case, recursive calls to the function also have access to the (single, statically allocated) variable.
[2] Instead, the local keyword gives a temporary, dynamically-scoped value to a global (package) variable, which lasts until the end of the enclosing block.
Randal L. Schwartz and Tom Phoenix argue that the operator local should have had a different name like save.
[5] Ruby as a language was inspired also by Perl, but in this case, the notation was made simpler: a global variable name must be preceded by a $ sign, like $variable_name, while a local variable has simply no $ sign in front of its name, like variable_name (while in perl all scalar values have a $ in front).