variable(n) Tcl Built-In Commands variable(n) ______________________________________________________________________________
NAME
variable - create and initialize a namespace variable
SYNOPSIS
variable name
variable ?name value...?
______________________________________________________________________________
DESCRIPTION
This command is normally used within a namespace eval command to create
one or more variables within a namespace. Each variable name is ini-
tialized with value. The value for the last variable is optional.
If a variable name does not exist, it is created. In this case, if
value is specified, it is assigned to the newly created variable. If
no value is specified, the new variable is left undefined. If the
variable already exists, it is set to value if value is specified or
left unchanged if no value is given. Normally, name is unqualified
(does not include the names of any containing namespaces), and the
variable is created in the current namespace. If name includes any
namespace qualifiers, the variable is created in the specified names-
pace. If the variable is not defined, it will be visible to the names-
pace which command, but not to the info exists command.
If the variable command is executed inside a Tcl procedure, it creates
local variables linked to the corresponding namespace variables (and
therefore these variables are listed by info vars.) In this way the
variable command resembles the global command, although the global com-
mand resolves variable names with respect to the global namespace
instead of the current namespace of the procedure. If any values are
given, they are used to modify the values of the associated namespace
variables. If a namespace variable does not exist, it is created and
optionally initialized.
A name argument cannot reference an element within an array. Instead,
name should reference the entire array, and the initialization value
should be left off. After the variable has been declared, elements
within the array can be set using ordinary set or array commands.
EXAMPLES
Create a variable in a namespace:
namespace eval foo {
variable bar 12345
}
Create an array in a namespace:
namespace eval someNS {
variable someAry
array set someAry {
someName someValue
otherName otherValue
}
}
Access variables in namespaces from a procedure:
namespace eval foo {
proc spong {} {
# Variable in this namespace
variable bar
puts "bar is $bar"
# Variable in another namespace
variable ::someNS::someAry
parray someAry
}
}
SEE ALSO
global(n), namespace(n), upvar(n)
KEYWORDS
global, namespace, procedure, variable
Tcl 8.0 variable(n)
tcl 8.6.7 - Generated Thu Aug 10 15:35:33 CDT 2017