scope(n)

🎀 scope(n) — the itcl::scope bestie briefing 🎀

okay so this page is literally from [incr Tcl], and it's all about itcl::scope. if you've ever needed a variable name to know where it came from even after it leaves the room, this is your girl. 💅

🌸 NAME 🌸

itcl::scope — capture the namespace context for a variable. periodt.

✨ SYNOPSIS ✨

itcl::scope name

🫶 DESCRIPTION 🫶

okay so scope creates a scoped value for the specified name, and that name must be a variable name. no exceptions, bestie.

if name is an instance variable, then the scope command returns a name that will resolve in any context as an instance variable belonging to object. the precise format of this name is an internal detail to Itcl — do not try to read its diary. using such a scoped value makes it possible to use instance variables in conjunction with widgets. for example, if you have an object with a private variable x, you can use x in conjunction with the -textvariable option of an entry widget. before itcl3.0, only common variables could be used in this manner. the more you know ✨

if name is not an instance variable, then it must be a common variable or a global variable. in that case, the scope command returns the fully qualified name of the variable, e.g., ::foo::bar::x. slay.

if name is not recognized as a variable, the scope command returns an error. oof 💀

ordinary variable names refer to variables in the global namespace. a scoped value captures a variable name together with its namespace context in a way that allows it to be referenced properly later. it is needed, for example, to wrap up variable names when a Tk widget is used within a namespace:

namespace foo {
    private variable mode 1

    radiobutton .rb1 -text "Mode #1"         -variable [scope mode] -value 1
    pack .rb1

    radiobutton .rb2 -text "Mode #2"         -variable [scope mode] -value 2
    pack .rb2
}

radiobuttons .rb1 and .rb2 interact via the variable "mode" contained in the namespace "foo". the scope command guarantees this by returning the fully qualified variable name ::foo::mode. iconic behavior, honestly 🦋

warning bestie — you should never attempt to craft your own scoped variable names, even if you believe you've flawlessly reverse-engineered the encoding. instead, you should always use the scope command to generate the variable name dynamically. then, you can pass that name to a widget or to any other bit of code in your program. no cap.

👑 KEYWORDS 👑

• code
• namespace
• variable

that's the whole vibe. source/version: itcl; page: scope(n); date: the footer didn't print one, so that's the tea. mwah 💖