Feature Request: new template behavior: switch statements

[NullVoxPopuli]

Possible usage:

{{#case this.property}}
  {{when "foo"}}  
    No fall-through, because having a {{break}} helper would be weird, imo.
  {{when "bar"}}

  {{when "baz"}}
    boop
{{/case}}

this could probably be implemented as an addon, actually, so I don't know how valuable this would be:

{{#switch this.property as |s|}}
  {{#s.when "foo"}}  

  {{/s.when}}

  {{#s.when "bar"}}

  {{/s.when}}
{{/switch}}

but then, as @miguelcobain mentioned, it'd be possible to render outside of the when blocks, which we wouldn't want.

[nickschot]

Wouldn't it make more sense to call it "case" instead of "when" to be consistent with the language?

[NullVoxPopuli]

what language? :)

[nickschot]

Javascript (and most other programming languages?)

[miguelcobain]

This syntax allows rendering things inside the switch but outside the whens.
This alternative, something that resembles {{#if}} {{else}} {{/if}} wouldn't have that "problem":

{{#switch this.property}}

{{when "foo"}}

{{when "bar"}}

{{else}}
  {{!-- a catch all case? --}}
{{/switch}}

Edit: on a second thought, it's not clear how to handle the first when/case. Perhaps:

{{#switch this.property when "foo"}}

{{when "bar"}}

{{else}}
  {{!-- a catch all case? --}}
{{/switch}}

¯_(ツ)_/¯

[NullVoxPopuli]

https://www.rubyguides.com/2015/10/ruby-case/
idk

    case capacity
    when 0
      "You ran out of gas."
    when 1..20
      "The tank is almost empty. Quickly, find a gas station!"
    when 21..70
      "You should be ok for now."
    when 71..100
      "The tank is almost full."
    else
      "Error: capacity has an invalid value (#{capacity})"
    end

[webark]

is this the point we start having the jsx conversation? 🤪😇🤓

[NullVoxPopuli]

in JSX, it's super easy to have unmaintainable code.

restrictions are beautiful ❤️ ✨ 🎉

[miguelcobain]

With the possibility of truth helpers landing in core, I'm not sure if it's worth a switch statement:

{{#if (eq this.property "foo")}}

{{else if (eq this.property "bar")}}

{{else}}

{{/if}}

Sure, a little bit more verbose and maybe more error prone because of the this.property repetition, but still not awful.

[kpfefferle]

Considering that Ember is a JavaScript framework, I would think we might favor the JS terminology of switch with case statements inside: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/switch

Note that switch was suggested as a built-in helper for Handlebars at one point (and then rejected as not-lightweight-enough).

I'd really like to see an addon that adds this as a Handlebars helper (the above Handlebars issue has some examples), but I'm not convinced it should be part of the core framework. I would definitely use it in some projects (I found the above link when looking for a switch helper just this week).

[NullVoxPopuli]

we could do an addon that does a build time transform that converts switch to ifs. I think that'd be neat.