classvariable — create link from local variable to variable in class
package require tcl::oo
classvariable variableName ?...?
The classvariable command is available within methods. It takes a series
of one or more variable names and makes them available in the method's scope;
those variable names must not be qualified and must not refer to array
elements. The originating scope for the variables is the namespace of the
class that the method was defined by. In other words, the referenced variables
are shared between all instances of that class.
Note: This command is equivalent to the command typevariable provided by
the snit package in tcllib for approximately the same purpose. If used in a
method defined directly on a class instance (e.g., through the
oo::objdefine method definition) this is very much like just
using:
namespace upvar [namespace current] $var $var
for each variable listed to classvariable.
This class counts how many instances of it have been made.
oo::class create Counted {
initialise {
variable count 0
}
variable number
constructor {} {
classvariable count
set number [incr count]
}
method report {} {
classvariable count
puts "This is instance $number of $count"
}
}
set a [Counted new]
set b [Counted new]
$a report
→ This is instance 1 of 2
set c [Counted new]
$b report
→ This is instance 2 of 3
$c report
→ This is instance 3 of 3
global, namespace, oo::class, oo::define, upvar, variable
class, class variable, variable
Copyright © 2011-2015 Andreas Kupries
Copyright © 2018 Donal K. Fellows