[Modules] Using variables inside a tcl command

[InfnPi <rob...@pi...>]

Here we go with another question, due to my lack of tcl knowledge.

What i would like to achieve is to be able to use variables in text printed to stderr inside a tcl command like module-whatis.

Very often in modulefiles you have to refer to the same information in more than one place and therefore it is convenient to use a variable.

as an example in a module installing tool XXX version YYY you write something like:

module-whatis (This module sets up software XXX version YYY}

and

proc ModulesHelp {} {
puts stderr {This module sets up software XXX version YYY}
}

Instead of writing "Version YYY" any times in different places it would be nice to be able to use:
set ver "Version YYY"
and then
module-whatis (This module sets up software XXX $ver}

this would reduce errors and add maintainability to the modulefile, in the sense that if a new version ZZZ of software XXX comes out i would (probably) use the same modulefile just replacing a few general variables.

Unfortunately in using
module-watis {This module sets up software XXX $ver} will not expand the variable $ver.

A workaround i found is to write it in the following way:
module-whatis "This module sets up software XXX $ver"
which expands variables (but you have to escape special characters).

Is this correct or does it have some unwanted consequences?


Along with this question there is a second one i would like to ask:

Is there a way to print text to stderr using colors?

I found a way to do it defining a procedure and some variables:

proc color {color text} {
   return [exec tput setaf $color]$text[exec tput sgr0]
}
set red 1
set green 2
set yellow 3
set blue 4

and then in the module file i will use:
module-whatis "This module sets up software [color $green XXX] $ver"

which will print XXX in green.

Is there a native way to do the same?
Is it fine to use it in the way i described?

Again, many thx in advance for all the answers.

Roberto