usual(3itk)

💖 usual(3itk) — bestie, it's giving default option-handling commands 💖

okay so real quick before we dive in: this page lives in the [incr Tk] manual, and it's all about usual, which is the little command that keeps your mega-widget components from making you type the same stuff over and over. slay. let's go 🫶

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✨ NAME ✨

usual — access default option-handling commands for a mega-widget component 💅

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✨ SYNOPSIS ✨

usual ?tag? ?commands?

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🌸 DESCRIPTION 🌸

okay so the tea is: usual gets used outside of an [incr Tcl] class definition, and its whole job is defining the usual set of option-handling commands for a component widget. no cap.

so like, when a component gets registered with the Archetype base class via the itk_component add method, that's when option-handling commands come into play. they specify how the component's configuration options should be integrated into the composite option list for the mega-widget. and your options can be kept, renamed, or ignored — all described over in the Archetype man page. iykyk 🦋

now here's the part where it gets good: it is so tedious to include the same declarations again and again whenever components are added. like, every single time?? 😭 so usual lets you register a standard code fragment for each widget class, which gets used by default to handle the options. iconic behaviour honestly.

and listen — all of the standard Tk widgets already have usual declarations defined in the [incr Tk] library. so if you're out here conceiving a brand new mega-widget class, you should be creating similar usual declarations too. and bestie, only the most-generic options should go in the usual declaration. keep it tight, periodt.

the tag name is usually the name of a widget class, which starts with a capital letter. (capital letter, main character energy, we love that.) but fr fr, any string registered here can be used later with the usual command described on the Archetype man page. so you do you.

now, depending on what you hand it:

• if the commands argument is specified, it gets associated with the tag string, and you can access it later via itk_component add. 🎀
• if only the tag argument is specified, this command goes looking for an existing tag name and returns the commands associated with it. and if there are no commands associated with tag, this command returns the null string. (yeah. empty. it's giving nothing. 💀)
• if no arguments are specified at all, this command returns a list of all tag names previously registered. a whole roster. 👑

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🌈 EXAMPLE 🌈

here's the usual declaration for the standard Tk button widget — literally, character for character:

itk::usual Button {
    keep -background -cursor -foreground -font
    keep -activebackground -activeforeground -disabledforeground
    keep -highlightcolor -highlightthickness
    rename -highlightbackground -background background Background
}

see how only the options that would be common to all buttons in a single mega-widget get kept or renamed? yeah. options like -text that would be unique to one particular button just get ignored. bye felicia 🙈

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⭐ KEYWORDS ⭐

itk, Archetype, component, mega-widget

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and that's the whole page bestie!! 💖 this one's from the itk 3.0 era of the [incr Tk] manual — undated on the page itself, but the version is right there, so you know exactly what you're working with. go forth and declare your usuals. mwah 💅✨