[George Peter Staplin] Dec 28, 2005 - I've been working on a project that needed to avoid infesting the global namespace with unprefixed names, so an obvious solution was to use [namespace].  However I can't do that as easily with [ProcMeUp], so I came up with an alternative solution that is also in my opinion superior, and simpler than using [namespace] (for some uses).  '''Why do I consider this superior?'''  It allows creating a namespace that is named whatever the user desires.

The concept is simple.  You prefix each proc with NS_ and each global with NS_.  NS_ is unlikely to occur in any other normal sequence, however of course it could be called something else.

 proc NS_foo {a b c} {
  global NS_var
  
  set NS_var [list $a $b $c]
 }

'''How does this allow the user to dynamically decide the namespace?'''

Let us imagine that the code above is in foo.tcl then we could do this:
 set fd [open [file join [file dirname [info script]] foo.tcl] r]
 eval [string map {"NS_" "super_"} [read $fd]]
 close $fd


That could all be factored into a proc such as source.namespace.  For example:
 proc source.namespace {f ns} {
 set fd [open $f r]
 #
 # We use uplevel #0 to eval in the global scope.
 #
 uplevel #0 [string map [list "NS_" $ns] [read $fd]]
 close $fd
 }

 source.namespace [file join [file dirname [info script]] foo.tcl] super_

So by now thanks to the [string map] we have:
  proc super_foo {a b c} {
   global super_var

   set super_var [list $a $b $c]
  }

This is also an easier way to update old packages, or code not designed for namespaces into an environment where their global variables or proc names would be problematic.

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