[Arjen Markus] (12 november 2003) In response to a recent discussion on the c.l.t. about a problem that arose in the context of regular expressions, I have started this page.
Its sole purpose: ''document dangerous constructs in Tcl''

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'''Using the subst command on arbitrary data:'''

   set a "Hello,"
   set b "world!"
   set string "$a $b"
   puts [substr $string]

gives:

 Hello, world!

but:

   set string "\[exit\]"
   puts [subst $string]

stops you program!

The subst command allows you to suppress the execution of commands:

   puts [subst -nocommands $string]

gives:

  [exit]

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Please: the next!
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[[
[Arts and crafts of Tcl-Tk programming]
]]