Perl Tcl::pTk read Tcl version

Question

I want to use Perl to read in the version of Tcl version that the module Tcl::pTk is linked to. I found the following which is working fine

use strict;
use warnings;

use Tcl::pTk;

my $int = new Tcl::pTk;

$int->Eval(<<'EOS');
# pure-tcl code to create widgets (e.g. generated by some GUI builder)
text .e
## http://wiki.tcl.tk/1626#tk_version
.e insert end "tcl_version      $tcl_version\n"
.e insert end "tcl_patchLevel   $tcl_patchLevel\n"
.e insert end "tk_version       $tk_version\n"
.e insert end "tk_patchLevel    $tk_patchLevel\n"
.e insert end "tk_library       $tk_library\n"
pack .e
EOS

my $e = $int->widget('.e');     # get .e entry into play
$int->MainLoop;

This displays the value in the GUI but I want to use $tcl_version in other parts of my script. In this I fail, as $tcl_version seems not to exist. I do not need the GUI part, just the values of the scalars.

Answer 1

The simplest thing that could possibly work should be tried:

my tcl_version = $int->Eval('info tclversion');

Alternatively and equivalently on the Tcl side:

my tcl_version = $int->Eval('set tcl_version');

All Tcl commands produce a result, so that ought to be reflected across here. Also, most of the time you are better off getting the patch-level for version reporting; the language version is just really for gross features, not anything detailed like system state reporting (e.g., you need the patch number for bug reports).

Answer 2

I've since found undocumented methods in Tcl::pTk, $int->tclVersion and $int->tclPatchlevel, which are equivalent to $int->Eval('info tclversion') and $int->Eval('info patchlevel') respectively.

They were already used internally in Tcl::pTk. I do not plan on removing these, but also do not know if it is a good idea to keep them in the long term or make them "public"/documented, so it may be better to stick with the existing answer's approach. (Tcl::Tk, which Tcl::pTk is based on, does not have these methods.)