TIP 151: Remove -e: Command Line Option from tclsh and wish

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by Aug 21.
Author:         Don Porter <dgp@users.sourceforge.net>
Author:         Don Porter <dgp@users.sf.net>
Author:         Donal K. Fellows <donal.k.fellows@man.ac.uk>
State:          Final
Type:           Project
Vote:           Done
Created:        22-Aug-2003
Post-History:   
Tcl-Version:    8.5

Abstract

This TIP proposes removal of the -e: command line option to tclsh and wish that was Accepted as part of [137].

Background

[137] was Accepted today. However, there were a few NO votes objecting to the new -e: form of the -encoding command line option for specifying the encoding of a startup script to tclsh and wish. Those voting NO only objected to that part of [137] while supporting the rest as a solid proposal that will improve Tcl. Among those voting YES, no one explicitly embraced the -e: command line option as something they required. Some voting YES opined that the -e: option was a wart that could be fixed later.

Based on those comments, [137] would have been better had the -e: form of the command line option not been part of the proposal. This TIP proposes nothing more than removing Acceptance of the -e: form of the -encoding command line option.

Without the controversial -e: proposal, I believe [137] would have had unanimous approval.

Rationale

The use of -e: as a command line option to tclsh or wish suffers when compared with the perl program. The perl -e option for evaluation of a Perl script provided on the command line is very well known, and it's a mistake to add something to tclsh that looks similar, but is in fact very different.

[137] proposed both -encoding and the -e: form. There's really no need to add multiple ways to do the same thing.

The Rationale in [137] for the -e: form is solely to support the 32-character limit in some Unices for their #! lines. However, the -e: form does not really solve that problem. For example:

 #!/usr/local/bin/tclsh8.5 -e:iso8859-15 
 12345678901234567890123456789012

Here we see that we still run afoul of the 32-character limit when tclsh is installed in the default location. Even longer encoding names exist which magnify the problem, and altering the installation location will not necessarily help:

 #!/usr/bin/tclsh8.5 -e:iso8859-15 
 12345678901234567890123456789012

(This is actually an insidious failure mode in that it leads to the script being sourced with a valid but incorrect encoding.)

Conversely, we already have an effective general workaround for the 32-character limit problem:

 #!/bin/sh
 # \
 exec tclsh -encoding iso8859-15 "$0" ${1+"$@"}

So, -e: doesn't solve a problem we don't really have, and it's controverisal. We should remove it.

Proposal

Remove (Acceptance of) the -e: set of command line options to the programs tclsh and wish.

Compatibility

Since no version of Tcl or Tk has been released supporting the -e: command line option, there are no compatibility issues to resolve.

Copyright

This document is placed in the public domain.

History