[LES]: The [Endekalogue] already provides some rules for the names of variables, but I thought this topic could be useful to clarify a few more details, especially to newcomers because Tcl allows a lot of liberty with the names of variables that other languages never have allowed and probably never will.

Since I am Brazilian and my language has more than the usual and meager 26 characters, I will begin with a few observations I have made in relation to special characters:

    * Tcl allows spaces in variable names. You just need to wrap the name with the brackets:

 % set {some variable name} 2
 % set {some variable name}
 2
 % puts ${some variable name}
 2

    * Tcl also allows special characters, so long as these are also wrapped in brackets:

 % set !@weird¬* "yikes!"
 % set !@weird¬*
 yikes!
 % puts ${!@weird¬*}
 yikes!

 % set acentuação "sim!"
 % set acentuação
 sim!
 % puts ${acentuação}
 sim!

Unfortunately, the cedilla and/or accented vowels are not considered "normal" characters. I could really swear it was not like that until not too long ago. But I am probably mistaken. Anyway, it's still better than most languages.

    * Even though the brackets are required whenever you refer to the '''content''' of the variable (when you use the '''$''' sign), they are not required when you refer to the variable's name, which gives us a lot of liberty:

 set !#@{blah}%¨& oi {1 2 3 4}
 foreach  i  [ set !#@{blah}%¨& ] {puts $i}
 1
 2
 3
 4

It also allows many interesting visual tricks:

 set foo "one little, two little, three little indians"
 regexp -all {(one).*(two).*(three).*}  $foo  =>  !g1 !g2 !g3

The last example creates four variables:

    * '''=>''' : one little, two little, three little indians
    * '''!g1''' : one
    * '''!g2''' : two
    * '''!g3''' : three


(LES will come back later with a more important aspect he wanted to bring up and forgot)  :-(