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

Abstract

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

Background

TIP #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 TIP #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, TIP #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 TIP #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.

TIP #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 TIP #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.

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