For a package, I want to write code that creates tables, where the exact type of table is configurable (tabular, longtable, tabularx, ... [Update: David rightly remarked that formats like tabularx ...
As I currently understand them, fully-expandable macros are analogous to pure/effect-free functions in functional programming. Correspondingly, things that are not expandable, such as \def, are ...
Possible Duplicate: What does \begingroup\expandafter…\endgroup do? In many of Heiko Oberdiek's packages one sees this type of construction: ...