c-box

components.c-box-body.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNames:['c-box-body']
});

components.c-box-head.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNames:['c-box-head']
});

components.c-box.js

import Component from '@ember/component';

export default Component.extend({
  classNames:['c-box']
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({});

templates.application.hbs

<h1>c-box</h1>

{{#c-box as |b|}}
	{{#b.body}}
  	Content
  {{/b.body}}
{{/c-box}}

<hr/>

{{#c-box title='Plain title' as |b|}}
	{{#b.body}}
  	Content
  {{/b.body}}
{{/c-box}}

<hr/>

{{#c-box as |b|}}
	{{#b.head}}
  	Custom title
  {{/b.head}}
	{{#b.body}}
  	Content
  {{/b.body}}
{{/c-box}}

templates.components.c-box-body.hbs

{{yield}}

templates.components.c-box-head.hbs

{{yield}}

templates.components.c-box.hbs

{{#let (hash
	head=(component 'c-box-head')
  body=(component 'c-box-body')
) as |data|}}
  
  {{!-- render title implicity if `title` property --}}
  {{#if title}}
    {{#data.head}}
      {{title}}
    {{/data.head}}
  {{/if}}
  
  {{!-- yield all data to consuming template --}}
  {{yield data}}
{{/let}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}