Tcl Tutorial Lesson 29

Information about procs - info

The info command includes a set of subcommands that will provide all the info you could want about a proc. These subcommands will return the body of a proc, the arguments to the proc, and the value of any default arguments.

These subcommands can be used to:

• Access the contents of a proc in a debugger.
• Generate custom procs from a template.
• Report default values while prompting for input.

Info commands that return information about a proc

info args procname

Returns a list of the names of the arguments to the procedure procname.

info body procname

Returns the body of the procedure procname.

info default procname arg varName

Returns 1 if the argument arg in procedure procName has a default, and sets varName to that default. Otherwise, returns 0.

Example

proc demo {argument1 {default "DefaultValue"} } {
    puts "This is a demo proc."
    puts "    It is being called with $argument1 and $default"
    #
    # We can use [info level] to find out if a value was given for
    # the optional argument "default" ...
    #
    puts "Actual call: [info level [info level]]"
}

puts "The args for demo are: [info args demo]\n"
puts "The body for demo is:  [info body demo]\n"

set arglist [info args demo]

foreach arg $arglist {
    if { [info default demo $arg defaultval] } {
        puts "$arg has a default value of $defaultval"
    } else {
        puts "$arg has no default"
    }
}

The args for demo are: argument1 default

The body for demo is:
     puts "This is a demo proc."
     puts "    It is being called with $argument1 and $default"
     #
     # We can use [info level] to find out if a value was given for
     # the optional argument "default" ...
     #
     puts "Actual call: [info level [info level]]"


argument1 has no default
default has a default value of DefaultValue