proc (n)
Create a Tcl procedure
SYNOPSIS
DESCRIPTION
The proc command creates a new Tcl procedure named
name, replacing
any existing command or procedure there may have been by that name.
Whenever the new command is invoked, the contents of body will
be executed by the Tcl interpreter.
Normally, name is unqualified
(does not include the names of any containing namespaces),
and the new procedure is created in the current namespace.
If name includes any namespace qualifiers,
the procedure is created in the specified namespace.
Args specifies the formal arguments to the
procedure. It consists of a list, possibly empty, each of whose
elements specifies
one argument. Each argument specifier is also a list with either
one or two fields. If there is only a single field in the specifier
then it is the name of the argument; if there are two fields, then
the first is the argument name and the second is its default value.
When name is invoked a local variable
will be created for each of the formal arguments to the procedure; its
value will be the value of corresponding argument in the invoking command
or the argument's default value.
Arguments with default values need not be
specified in a procedure invocation. However, there must be enough
actual arguments for all the
formal arguments that don't have defaults, and there must not be any extra
actual arguments. There is one special case to permit procedures with
variable numbers of arguments. If the last formal argument has the name
args, then a call to the procedure may contain more actual arguments
than the procedure has formals. In this case, all of the actual arguments
starting at the one that would be assigned to args are combined into
a list (as if the list command had been used); this combined value
is assigned to the local variable args.
When body is being executed, variable names normally refer to
local variables, which are created automatically when referenced and
deleted when the procedure returns. One local variable is automatically
created for each of the procedure's arguments.
Global variables can only be accessed by invoking
the global command or the upvar command.
Namespace variables can only be accessed by invoking
the variable command or the upvar command.
The proc command returns an empty string. When a procedure is
invoked, the procedure's return value is the value specified in a
return command. If the procedure doesn't execute an explicit
return, then its return value is the value of the last command
executed in the procedure's body.
If an error occurs while executing the procedure
body, then the procedure-as-a-whole will return that same error.
KEYWORDS
argument, procedure
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