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Tcl - nice and nasty

Archive - Originally posted on "The Horse's Mouth" - 2009-06-29 21:54:41 - Graham Ellis

Tcl is a lovely engineers language ... but goodness you can do some nasty things with it, and write some unmaintainable code.

set count 1
foreach type {if while} {
  $type {$count < 5} {
    puts "yay $type $count"
    incr count
  }
}

Which runs as follows:

earth-wind-and-fire:~ grahamellis$ tclsh tty
yay if 1
yay while 2
yay while 3
yay while 4
earth-wind-and-fire:~

A sign of a pure interpretative language ... the code changing from an if to a while as it runs. Is this:
a) An example of how you should NOT write code
b) An example of polymorphism when you least expect it
c) A feature looking for a benefit
d) All three of the above
And the answer is, of course, (d)