example(html-template): atomic-design layout + Props pattern + no-Clone urlFor

[jackielii]

Summary

Pure example PR. Demonstrates how to scale an html/template-based structpages app:

1. Atomic-design directory layout with slash-namespaced template names — paralleling templ's examples/blog/.
2. Props pattern for the new /post page: a single Props() method centralizes data loading; Page / Main / Comments component methods receive the loaded props.
3. No-Clone helper pattern wired up in user code — template funcs take ctx as their first argument, so the FuncMap registers once at parse time and the same parsed *template.Template handles every request.

No library changes. The two helpers (urlFor, args) live right next to tpl in the example so the lesson is the pattern, not an API to import.

Atomic-design layout

templates/
  layout/public.html              # {{ define "layout/public" }}
  ui/atoms/button.html            # {{ define "ui/atoms/button" }}
  ui/molecules/card.html          # {{ define "ui/molecules/card" }}
  post/comments-list.html         # organism, HTMX-targetable
  post/page.html                  # {{ define "body" }} for /post
  pages/{index,product,team,contact}.html

Slash-namespaced template names match the directory tree. The new /post route demonstrates the full pattern: layout + 2 molecule cards (built with args) + a comments-list organism that HTMX-swaps independently.

Props pattern

func (post) Props() postProps { … }                       // single load point
func (post) Page(props postProps) tpl     { … }
func (post) Main(props postProps) tpl     { … }
func (post) Comments(props postProps) tpl { … }

structpages calls Props once per request, then dispatches to the matched component method passing the props as an argument.

tpl.Render — no Clone

func (p tpl) Render(ctx context.Context, w io.Writer) error {
    t, ok := pageTmpls[p.page]
    if !ok { return fmt.Errorf("unknown page %q", p.page) }
    return t.ExecuteTemplate(w, p.entry, view{Ctx: ctx, Data: p.data})
}

view{Ctx, Data} is the example's chosen template-dot shape; nothing prescribes it. Templates call {{ urlFor .Ctx "Product" }}.

Test plan

• go test ./..., go vet ./..., golangci-lint run (via pre-commit hook)
• Manual smoke of examples/html-template/:
  • full GET /post → layout + atoms/molecules + organism inline
  • HTMX nav swap (HX-Target: main) → just the body (Main(props))
  • HTMX organism swap (HX-Target: section#comments) → just the comments-list partial (Comments(props))
  • HX-Request-Type: full → full layout

Reviewer notes

• The branch history reflects iteration through several library-API ideas (View[T], then helpers-only, then nothing); net diff is example-only. Squash on merge if the back-and-forth is noise.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.78%. Comparing base (449e74d) to head (55285f1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #6      +/-   ##
==========================================
+ Coverage   96.65%   96.78%   +0.12%     
==========================================
  Files          13       12       -1     
  Lines        1197     1183      -14     
==========================================
- Hits         1157     1145      -12     
+ Misses         26       24       -2     
  Partials       14       14              

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