http://tcllib.sf.net/doc/no-op.html no-op is available via the [tcllib] [control] structure module. ---- [AMG]: I'm not sure if this is how [tcllib]'s no-op is implemented, but it can be done very simply: proc no-op {args} {} I believe the [bytecode] compiler specially recognizes and optimizes this. ---- GraemeP: That is how tcllib does it. There is a discussion on [interp alias] about creating a no-op, and a command that just returns its args. ---- !!!!!! %| [Category Package] | [Category Tcllib] | [Category Control Structure] |% !!!!!!