[Robert Abitbol] There are a lot of basic TCL formulas which are needed and useful in a lot of programs. This is some of them. Since I am a beginner, please don't be shy and don't hesitate to contradict me if what I am saying is wrong! Thanks! 

[AM] (16 february 2005) Just a matter of idiom: the common word for this seems to be ''idiom'' - formula makes me think of magic incantations or pseudo-scientific inventions in old movies :)

[MG] See also [Bag of Algorithms], [Example Scripts Everybody Should Have], and all the other pages mentioned on those two.

-----
'''1) Calling a box with some text'''

- Calling a box with a text: easy! 
Ex:
 tk_messageBox -message "Sorry, this function isn't ready yet."

The full function would be: 

 proc preferences {} {
    tk_messageBox -message "Sorry, this function isn't ready yet. Come back later :-)"
 }

[phk] How about this:
 
 proc preferences {text} {
    tk_messageBox -message $text
 }

then you can call it from different places, using appropriate texts.

The proc name could be possibly changed to messageBox (makes it more universal).

Have a look at the tutorials.

[MAK] Or, hey, to make it really universal, how about tk_messageBox and make it take optional switches and... oh wait.  (I too am puzzled by the purpose of a proc called "preferences" that displays a dialog box saying the function isn't ready yet, as a "full" function.)  Why not "notImplemented"?  But, really, why would "messageBox $text" be better than "tk_messageBox -message $text"?  A "proc puts_error { text } { puts stderr $text }" would be about as useful.

[RS] As this is just a case of currying, one could also use
 interp alias {} messageBox {} tk_messageBox -message
 interp alias {} puts_error {} puts stderr

-----
- More to come