Version 7 of rename

Updated 2007-02-06 15:01:11 by GDE

The documentation for the [rename] command is available at http://purl.org/tcl/home/man/tcl8.5/TclCmd/rename.htm .

The [rename] command is most often used for wrapping commands. In other words, the programmer uses [rename] to hide another command -- so that a wrapper can be placed around the hidden command to change its behavior. Examples of this important concept abound on the Wiki; among the clearest are: DGP: Be aware that if you rename a command into another

[Discuss examples. Explain errorInfo subtleties (refer to live examples). Explain "return [eval ::_$original_command \$first_argument $args]" idiom.]

RS Another frequent application for rename is to remove commands, by renaming them to the empty string:

 rename foo {}

DGP Be aware that if you [rename] a command into another namespace, its evaluation context will change to that namespace. HaO 2010-04-10: (discussion on CLT ): rename or delete from inside targeted proc is allowed:

  % namespace eval one {
    variable message "I'm in one"
    proc test {} {variable message; return $message}
  }
  % namespace eval two {variable message "I'm in two"}
  % rename one::test two::test
  % two::test
  I'm in two

GDE What's the recommended way to test for the pre-existence of the "destination" argument proc to avoid an error at runtime? The best I could come up with is:

  if {![llength [info commands new_proc_name]]} {
    rename old_proc_name new_proc_name
  }

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