Undeclared identifier calling a mixin with a template parameter.

[GrundleTrundle]

I've tried this on 0.16.0 and the development branch of Nim.

Here's the code:

import 
  emerald, streams 

proc mixin_with_params(content: string) {.html_mixin.} = 
  p: content

proc genSummaryPage(thingy: string) {.html_templ.} = 
  body:
    call_mixin mixin_with_params(thingy)

proc doit() = 
  let
    outfs = newFileStream(stdout)
    t  = newGenSummaryPage()

  t.thingy = "blah"
  t.render(outfs)

doit()

Compiling it gives me this error:

hg.nim(7, 37) template/generic instantiation from here
hg.nim(9, 34) Error: undeclared identifier: 'thingy'

It seems specific to passing the thingy parameter to the mixin. Replacing call_mixin mixin_with_params(thingy) with call_mixin mixin_with_params("a string") works fine, and I can reference thingy in other parts of the template. Just not as a mixin parameter.

[flyx]

This issue shows that emerald is more a tech demo than an actually useful tool for complex tasks. Sometimes, because something is possible does not mean that it is feasible.

This is a conceptual problem an I think the correct way to solve it is to implement the call-by-name-ALGOL-rule for parameter resolution.

That being said, it is unlikely that I will invest more work into this project, since I came to believe that while it is a pretty nice tech demo, it is not a great tool to tackle actual problems.

[GrundleTrundle]

I understand, thanks for the response.