Pass variables to base layout from extending pug/jade template

Question

I would like to set a class on the body tag by declaring a variable in a template that extends a base layout.

When I try, the body_class variable is undefined in the layout.

It appears the layout is executed before the extending template, or they are executed in different scopes or something.

Is there another way? Would a mixin work here?

_layout.jade:

doctype html
html(lang="en-au")
    head
        meta(charset="utf-8")
        block css
    body(class=(body_class || "it-did-not-work"))
        block header
        block content
        block footer

home.jade:

var body_class = 'i-am-the-home-page'
extends _layout
block header
    h1 home

Answer 1

Ah ha! Figured it out.

Create a block at the top of the base layout and add your variables in there.

_layout.jade:

block variables
doctype html
html(lang="en-au")
    head
        meta(charset="utf-8")
        block css
    body(class=(body_class || "it-did-not-work"))
        block header
        block content
        block footer

home.jade:

extends _layout
block variables
    - var body_class = 'i-am-the-home-page'
block header
    h1 home