CODEWITHSUNDEEP
tcl
my_question
my_question

Reputation: 3235

Can namespace be variable

namespace must be plain text, it cannot be meta elements such as variable or nesting script. E.g. there is no way you can do the following:

set ns ::my_ns
set ::my_ns::var1 100
puts ${$ns}var1     <== wrong
puts $$nsvar1     <== wrong

Could you confirm?

Upvotes: 0

Views: 64

Answers (2)

Donal Fellows
Donal Fellows

Reputation: 137557

You can't use the $ syntax to do this; this is a syntactic limitation. You have to use something like the single-argument form of set:

puts [set ${ns}::var1]

BUT you have a much better option available to you if you are inside a procedure. The namespace upvar command handles this sort of thing nicely:

proc printVariable {ns} {
    namespace upvar $ns var1 v
    puts $v
}

Also, if you're doing this to simulate an object system, please stop. Use a real object system instead (e.g., TclOO, which ships as a built-in part of Tcl 8.6).

Upvotes: 1

Colin Macleod
Colin Macleod

Reputation: 4372

This works:

% namespace eval my_ns { set var1 100 }
100
% incr ::my_ns::var1
101
% set ns ::my_ns
::my_ns
% puts [set ${ns}::var1]
101

Upvotes: 2

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