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.