Added optional attributes

[ttp]

Usage:

%input{checked?: model.isChecked(), disabled?: model.isDisabled()}
%input{checked?: model.isChecked(), readonly?: model.isChangable()}

this adds these attributes only if model returns "not false" value

For now I have to duplicate such blocks with combinations of these attributes

:if (model.isChecked())
  %input{type: "checkbox", ..., checked: true}
:else
  %input{type: "checkbox", ...}

[aaronblohowiak]

please add tests.

[ttp]

@aaronblohowiak tests added

[dblock]

+1 this is super useful

[bogn]

It's definitely needed functionality. Adding CSS classes depending on some conditions is even more important. This really shouldn't be necessary:

            :if (app.identifier === App.Configuration.app_id)
              %li.active
                %a(href=app.url)= app.name
            :else
              %li
                %a(href=app.url)= app.name

and it will get out of hand quickly when the markup get's more complex.