What are the advantages of dynamic scoping?

Question

I\'ve learned that static scoping is the only sane way to do things, and that dynamic scoping is the tool of the devil, and results only from poor implementations of interpr

Answer 1

Dynamic scoping is useful in some domain-specific languages. In particular, it can be handly in stylesheet languages. My experience is from the GNU TeXmacs stylesheet language.

In this language display parameters are stored in dynamically scoped variables. Those variables affect the rendering of every atom in their scope, including atoms that are produced by functions called in the scope.

Dynamic scoping in TeXmacs is also used, among other things, for labeling cross-references. Anchors used for cross references get their label from their environment. For example, an anchor included in a formula block will use the formula number as label, instead of the section number for an anchor located after the formula.

Come to think of it, unix environment variables are also dynamically scoped variables. Albeit inner scopes cannot alter the value of variables in outer scopes.

As Barry Kelly noted, dynamic scoping can also be useful to implement language features that care about the call scope, such as exception handling, or context-dependent permission handling. In the presence of continuations, scopes can be entered and exit without walking through the call stack.