Add {{elseif}} sugar syntax

[akanix42]

Implements #39.

{{#if counterIsAt 2}}
    test
{{elseif counterIsAt 3}}
    test3
{{elseif counterIsAt 4}}
    test4
{{else}}
    test5
{{/if}}

Working example here: https://github.com/nathantreid/blaze-test-issue-39

[mitar]

@nathantreid: This is great work. Can you please resolve merge conflicts? And add also all changes to documentation (spacebars API, mention this also somewhere in guide, blaze itself, and so on)?

We have now documentation in this repository, so you can just update this pull request.

[mitar]

BTW, Handlebars seems to have else if.

See also example in documentation. It seems the syntax is:

{{else if isInactive}}

And also:

{{else unless isInactive}}

Or in general it seems it can be {{else <any block helper>}}.

It is not necessary to use the same helper in subsequent calls, the unless helper could be used in the else portion as with any other helper. When the helper values are different, the closing mustache should match the opening helper name.

While I dislike this syntax, I see benefit of having it match Handlebars, and benefit of supporting any block helper. Implementation might be a bit trickier to implement, but this sugar is easy to do:

{{#if foo}}

{{else something bar}}

{{/if}}

Becomes:

{{#if foo}}

{{else}}
  {{#something bar}}

  {{/something}}
{{/if}}

@nathantreid, could you implement it this way?

[stubailo]

Yikes.... that seems kind of odd. Are we sure we want to think about handlebars at all? Honestly Handlebars doesn't seem that well designed to start with.

[mitar]

For this particular feature I think I would. I would change what this means inside a template, but for syntax I would try to stick with Handlebars.

[mitar]

Also, this syntax seems to map nicely to the sugar we are trying to make.

[akanix42]

I also think that the {{else if}} syntax looks odd, perhaps we could put that up for a vote?
I personally don't have any desire to match Handlebars going forward, unless of course it's because the syntax actually makes a lot of sense on its own.

[mitar]

It is not just a syntax here, but also a feature. So that you can use any block helper in this way. elseif does not support that. I think that a feature of else <blockname> is a good one. I use quite some custom block helpers (Blaze Components add extra power to them).

[mitar]

@nathantreid, I really love your work here and I think many people would like to see this in. But I also really like that the Handlebars syntax work with arbitrary block helpers. I think that block helpers are really powerful feature of Blaze and with allowing such chaining of them it would be really powerful. Currently block helpers were a bit strange to use because what if you had only two cases, but now you can potentially get multiple cases supported, not just true/false.

Could you please update the pull request to support arbitrary block helpers?

[mitar]

So something like this could then work:

{{#tab title="Foo"}}

{{else tab title="Bar"}}

{{else tab title="Baz"}}

{{/tab}}

And have a block helper which renders dynamically tabs, opens/closes them, etc.

[akanix42]

I'd be happy too, but I'm swamped right now IRL. If someone else wants to have a go at it, be my guest. Otherwise, I'll try to get to it as soon as I can.

[mitar]

No worries. I just wanted to make sure we have a path forward.

[mitar]

Any progress here? Anyone else wants to tackle this?

[kulttuuri]

This would be fantastic feature to have. @nathantreid still busy with things IRL? :)

[mitar]

I cleaned master branch to remove all Meteor history (#112). This means the pull request should be also updated to new history to not base it on old commits. Sorry for this extra work.

[mitar]

With 2fa3cab I implemented the Handlebars syntax for chaining block tags. I am closing this pull request in favor of that.

[mitar]

Released as 2.3.0. You have to update templating package.