Component Boolean Arguments

text/0000-component-boolean-arguments.md

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+- Start Date: 11/30/2018
+- RFC PR: (leave this empty)
+- Ember Issue: (leave this empty)
+
+# Component boolean Arguments
+
+## Summary
+
+This RFC proposes to add a boolean argument to components, that aligns with boolean attribute of regular DOM elements.
+
+## Motivation
+
+Currently to pass a boolean property to a component a developer has to explicitly pass `true` as an argument.
+e.g.
+```hbs
+<Button @secondary={{true}} />
+```
+This does allow the value to be a variable e.g.
+
+```hbs
+<Dialog @visible={{this.visible}} />
+```
+
+If the value is not a variable `{{}}` can actually be ommited as a `true` string is truthy leading to somewhat easier to remember syntax of
+```hbs
+<MyHackyBoolArgument @bool=true />
+```
+
+For simple usecases  it is verbose to write and does not align with HTML attributes like `disabled` of which value can be ommited as desribed in [HTML Spec](https://www.w3.org/TR/html5/infrastructure.html#sec-boolean-attributes)
+
+## Detailed design
+
+This RFC proposes that if argument is passed without any value it should have value `true` set inside of a component.
+
+```hbs
+<Form @disabled />
+```
+inside the Form component `@disabled` would equal to `true`.
+
+This RFC also proposes that it should be possible to pass attributes without an explicit value e.g.
+
+```hbs
+<Input disabled />
+```
+
+and inside a component `...attributes` should also contain `disabled` attribute. e.g.
+
+```hbs
+<input ...attributes>
+```
+should render as:
+```html
+<input disabled>
+```
+
+
+## How we teach this
+
+This should be included in guides and also should be easier to teach as it is inline with HTML spec for attributes.
+
+## Drawbacks
+
+Can't think of any at the moment.
+
+## Alternatives
+
+- In React if a prop is passed with no value it is truthy inside of a component.
+- In Vue if a prop is passed with no value it is falsy inside of a component.
+
+## Unresolved questions
+
+None at the moment.