TIP 214: Add New Object Introspection Command

FlightAware bounty program for improvements to Tcl and certain Tcl packages.
Author:         Ulrich Schöbel <usus@aladyn.de>
Author:         Larry W. Virden <lvirden@yahoo.com>
State:          Withdrawn
Type:           Project
Vote:           Pending
Created:        24-Aug-2004
Keywords:       Tcl,info,representation
Tcl-Version:    8.7
Obsoletes:	117


This TIP proposes the new representation subcommand to info which returns the internal representation of a variable's contents.


Inspired by a posting on news:comp.lang.tcl by Victor Wagner, I considered a facility to obtain the internal representation of the value of a variable to be useful.

  • It further extends the Tcl introspection commands.

  • It offers a method to check the type of a variable without conversion.

  • During the development process it is useful to detect/avoid shimmering and its negative performance effects.

Proposed Change

Add the new subcommand info representation with the following syntax:

info representation varName

It returns the type of the variable varName or an error, if

  • varName doesn't exist,

  • varName is an array and no index is provided,

  • varName is a scalar variable but an index is provided.


A patch against Tcl8.4.6 is available http://sf.net/support/tracker.php?aid=1015338 .


This document has been placed in the public domain.