Block support / Looping

[garymardell]

Adding support for arrays and block notation would be a massive step in making scribble an alternative for liquid.

Example concept.

{{ items.each do |item| }}
  {{ item }}
{{ end }}

Working out how to implement this so if you have any pointers where to begin let me know.

[stefankroes]

Dear Gary,

Cool! I totally agree that this is the next thing that needs to be added. Eventually I want to add an array literal [] but that will be much harder than just adding an each method which has a lot of value on its own.

Syntactically I was thinking along the lines of

{{ items.each 'item' }}
    {{ item }}
{{ end }}

We don't need a do keyword since Scribble assigns blocks to methods automatically depending on which methods are (globally) registered as block methods. The code above can already be parsed so you would only need to add an each methods, similarly to how you added the unless method. The method would render its block multiple times, each time setting the item variable in that block to a different value by using set_variable (not @context.set_variable). Take a look at the times method for how to registerer a block method on a specific receiver, in this case Array.

When you are 'inviting' people to pass arrays into scribble, array should also be defined in the objects folder with its own name (list?), to_boolean (empty is false?) and to_string ([,,,]?). If you feel like it and are up to it, you could also expose some basic methods like size, reverse, etc. I personally think add, subtract and multiply should implement concatenation, deletion and repetition like they do on string. There is some documentation on how to do this and there are examples for other classes in the objects folder.

I have also been thinking about an alternative to the syntax above that would require some more extensive changes to the implementation:

{{ items.each item }}

I think this is an easier syntax for novice users but it would require you to register the argument as a special type that would instruct the runtime to not evaluate it as a variable but to return its name instead to the each method as a something like a Scribble::Variable. It might however be counter-intuitive as this would yield a name error on item if each was undefined, misspelled or defined differently.

Other alternatives would be passing the item between pipes like in Ruby |item| or as a symbol :item. However, both seem kind of unnecessary to me, a string is fine and is something users have to learn about anyway.

Good luck, thank you for helping out,

With kind regards,

Stefan

[ryanong]

This is now implemented! WOO HOO! I should probably write some documentation for it...