12.5.40    upvar

Description:   Create link to variable in a different stack frame

Syntax:         upvar ?level? otherVar myVar ?otherVar myVar ...?


Argument:     level, upper variable, new local variable


See Also:       proc, namespace



#example 1

# Arguments:

#      var    Variable name for associative array in the calling

#             proc containing the specification for this send.


proc smtp_begin {s var} {

    upvar 1 $var cur



This command arranges for one or more local variables in the current procedure to refer to variables in an enclosing procedure call or to global variables. Level may have any of the forms permitted for the uplevel command, and may be omitted if the first letter of the first otherVar isn’t # or a digit (it defaults to 1). For each otherVar argument, upvar makes the variable by that name in the procedure frame given by level (or at global level, if level is #0) accessible in the current procedure by the name given in the corresponding myVar argument. The variable named by otherVar need not exist at the time of the call; it will be created the first time myVar is referenced, just like an ordinary variable. There must not exist a variable by the name myVar at the time upvar is invoked. MyVar is always treated as the name of a variable, not an array element. Even if the name looks like an array element, such as a(b), a regular variable is created. OtherVar may refer to a scalar variable, an array, or an array element. Upvar returns an empty string.