BxSites Variables & Magic Functions

Two ways to keep repeated facts/logic out of Markdown - both share one syntax:

{{ dotted.path }}          # a reusable variable
{{ $name(arg1, arg2) }}    # a magic function call

Reusable variables

Add a variables block to bxsites.yaml (see bx-sites-configuration), any shape, flat or nested:

variables:
  company: "Ortus Solutions"
  product:
    name: "BoxLang"
    supportEmail: "[email protected]"

Reference by dotted path from any page:

# Welcome to {{ company }}

We build {{ product.name }} tools. Need help? Write us at
{{ product.supportEmail }}.

Resolved once, at build time, against bxsites.yaml's current variables - change it once, every page picks it up on the next build.

variables is a single, project-wide block - not itself translatable per locale. A multilingual project wanting different text per language should use a magic function switching on siteConfig.i18n.defaultLocale.code, or keep the value locale-neutral.

Magic functions

Add docs/functions.bxs (or src/functions.bxs) - a plain BoxLang script. Any function named with a leading $ becomes callable from {{ }} in Markdown, and bare (no $) from a project theme/ .bxm override (see bx-sites-themes):

function $shout( text ) {
	return uCase( arguments.text ) & "!"
}

function $badge( label, kind = "info" ) {
	return '<span class="badge bg-' & arguments.kind & '">' & arguments.label & '</span>'
}

{{ $shout('this is important') }}

Status: {{ $badge('Stable', 'success') }}

A magic function can return anything toString()-able (plain text, HTML, a number) - it's spliced into the page's Markdown before conversion, so returning real HTML works exactly as expected. A function without a leading $ is a private helper other $-functions in the same file can call bare; {{ }} can never call it directly.

Calling from a theme override - a magic function is bound directly into template scope, so theme/page.bxm/layout.bxm can call it bare:

<p class="build-banner">#$shout( 'built with boxlang' )#</p>

Context variables

Available bare, with no argument, inside any magic function body:

Variable	What it is
siteConfig	The resolved bxsites.yaml config
page	The current page (see caveat below)
nav	This tree's own nav tree
basePath	Root-relative base path, ending with /
versions	Version-switcher entries - [ { label, url } ]
currentVersion	Which versions entry is rendering now
locales	Language-switcher entries - [ { code, label, url, dir, flag } ]
currentLocale	Which locales entry's code is rendering now
currentLocaleDir	"ltr"/"rtl" for the current locale

page isn't equally complete everywhere. Called from Markdown, page is this page's own struct as loaded from disk - title/description/ tags/icon/summary/ogImage/urlPath/relativePath/body/etc. exist, but fields only known once the whole tree has converted (toc, prevPage/nextPage, breadcrumbs, editUrl/lastUpdated, iconHtml, markdownUrl, canonicalUrl) don't yet. Called bare from page.bxm, page is fully enriched, all of those included. Every other context variable is identical in both places.

Argument syntax

Simple, comma-separated literals or variable references only - no nested calls or expressions:

• Numbers: {{ $discount(20) }}
• Quoted strings: {{ $greet('World') }} or {{ $greet("World") }}
• Booleans: {{ $badge('Beta', true) }}
• A dotted variable reference: {{ $greet(product.name) }}

Visualizer recipes

A magic function returning HTML is a general-purpose way to get GitBook-style visual cells (a star rating, a colored chip, a progress bar) without a database-backed column picker. Drop these (or adapt them) into docs/functions.bxs:

function $stars( required numeric rating, numeric max = 5 ) {
	var filled = min( max( round( arguments.rating ), 0 ), arguments.max )
	var stars = repeatString( "★", filled ) & repeatString( "☆", arguments.max - filled )
	return '<span title="' & arguments.rating & ' out of ' & arguments.max & '" style="color:#f5a623;letter-spacing:2px">' & stars & '</span>'
}

function $badge( required string label, string kind = "info" ) {
	var palette = {
		"info"    : { "bg" : "#e0edff", "fg" : "#1d4ed8" },
		"success" : { "bg" : "#dcfce7", "fg" : "#15803d" },
		"danger"  : { "bg" : "#fee2e2", "fg" : "#b91c1c" },
		"warning" : { "bg" : "#fef9c3", "fg" : "#854d0e" }
	}
	var pick = palette.keyExists( arguments.kind ) ? palette[ arguments.kind ] : { "bg" : "#f1f5f9", "fg" : "#475569" }
	return '<span style="display:inline-block;padding:0.1em 0.6em;border-radius:999px;font-size:0.85em;font-weight:600;background:'
		& pick.bg & ";color:" & pick.fg & '">' & encodeForHTML( arguments.label ) & "</span>"
}

function $progress( required numeric percent ) {
	var pct = min( max( arguments.percent, 0 ), 100 )
	return '<span style="display:inline-block;width:120px;height:8px;background:#e5e7eb;border-radius:999px;overflow:hidden;vertical-align:middle"><span style="display:block;height:100%;width:'
		& pct & '%;background:#2563eb"></span></span> ' & pct & "%"
}

function $trend( required numeric value ) {
	var isUp = arguments.value >= 0
	var arrow = isUp ? "▲" : "▼"
	var color = isUp ? "#16a34a" : "#dc2626"
	var sign = isUp ? "+" : ""
	return '<span style="color:' & color & ';font-weight:600">' & arrow & " " & sign & numberFormat( arguments.value, "0.0" ) & "%</span>"
}

Note: when writing these into a real docs/functions.bxs, every literal # in a hex color above must be doubled (##) inside a BoxLang string, since #...# is interpolation syntax - e.g. "##f5a623" not "#f5a623". Shown single here for readability.

Usage: `{{ $stars(4) }}`, `{{ $badge('Stable', 'success') }}`, `{{ $progress(72) }}`, `{{ $trend(4.2) }}`.

Inside a table cell - {{ }} resolves against raw Markdown before tables are even parsed (see bx-sites-markdown for table syntax), so any magic function works inside a pipe table cell, the closest thing here to GitBook's Select/Rating columns:

| Feature | Status | Rating |
| --- | --- | --- |
| Dark mode | {{ $badge('Stable', 'success') }} | {{ $stars(5) }} |

Showing the syntax literally

A {{ }} inside a fenced code block (3+ backticks) is left completely untouched. A {{ }} in inline code (single or double backticks) is protected too. A {{ }} whose contents don't look like a variable path or a $name(...) call (some other templating engine's own {{ }} shown in prose) is left untouched rather than erroring - only a token that looks like a variable/magic-function reference but doesn't resolve fails the build.

Scope

• functions.bxs is project-wide - one file, loaded once, available on every page across the main tree and every version/locale tree (see bx-sites-blog-versioning-i18n). No need to duplicate it into docs/versions/<name>/ or docs/i18n/<code>/.

Reserved names

A theme override calling a magic function bare works because every loaded function is bound directly into that template's rendering scope, alongside the built-ins it already reads. Avoid naming a private helper (no $ prefix) any of: page, nav, siteConfig, themeDir, basePath, moduleAssetsDir, versions, currentVersion, locales, currentLocale, currentLocaleDir, strings, requiredFiles, stringsResolver - a $-prefixed magic function can never collide with any of these since none start with $.

Errors

• BxSites.UnknownVariable - a {{ dotted.path }} doesn't match anything in variables.
• BxSites.UnknownFunction - a {{ $name(...) }} doesn't match any $-function in functions.bxs.
• BxSites.InvalidFunctions - functions.bxs has a BoxLang syntax error.
• BxSites.InvalidConfig - variables is present but isn't an object.