TIP:		358
Title:		Suppress Empty List Element Generation from the Split Command
Version:	$Revision: 1.2 $
Author:		George Petasis <petasis@iit.demokritos.gr>
State:		Draft
Type:		Project
Tcl-Version:	8.7
Vote:		Pending
Created:	04-Oct-2009
Post-History:	
Keywords:	Tcl, list extraction, parsing

~ Abstract

The '''split''' command will create empty list elements when adjacent split
characters are found in the input. In some cases these empty list elements are
not desired, so this TIP proposes a new switch to disable their generation.

~ Rationale

The idea for this TIP came from a discussion in comp.lang.tcl:
[http://groups.google.gr/group/comp.lang.tcl/browse_thread/thread/8d46b0f10e7a5750/d7844cc739aa4310]
and the (non obvious) suggestions on how tokens can be extracted from a string
can be performed efficiently.

It should be noted that this will allow the '''split''' command to be used in
a fashion that is very similar to how splitting works in many other languages
(e.g., Perl, awk, Unix shells).

~ Specification

This TIP proposes a new optional switch ('''-noemptyelements''') to the
'''split''' command:

 > '''split -noemptyelements''' ''string'' ?''splitChars''?

If this option is present, then '''split''' will not produce an empty list
element when the ''string'' contains adjacent characters that are present in
''splitChars''.

~ Reference Implementation

Currently there is no patch, but it should be quite easy to implement this.

~ Copyright

This document has been placed in the public domain.