Support hx-swap modifiers in a type-safe way

[angelofallars]

After some research, it turns out that HTMX supports modifier attributes in hx-swap. E.g. swap:1s, settle:1s and scroll:bottom. https://htmx.org/attributes/hx-swap/

There's a lot of possible modifier attributes, but most of them can be represented by a finite amount of values. I'd like to see an implementation that is type-safe as much as possible.

Example possible implementations:

htmx.NewResponse().
  Reswap(htmx.SwapWithAttr(htmx.SwapOuterHTML, htmx.ModFocusScroll(true))
// [Output header]
// HX-Reswap: outerHTML focus-scroll:true

htmx.NewResponse().
  Reswap(htmx.SwapWithAttr(htmx.SwapBeforeEnd, htmx.ModScrollBottom())
// [Output header]
// HX-Reswap: beforeEnd scroll:bottom

htmx.NewResponse().
  Reswap(htmx.SwapWithAttr(htmx.SwapInnerHTML, htmx.ModShowTop("#another-div"))
// [Output header]
// HX-Reswap: innerHTML show:#another-div:top

Edit: This possible implementation looks good too, implementing methods on the htmx.swapStrategy type (which is just derived from string) that return a new swapStrategy value:

htmx.NewResponse().
  Reswap(htmx.SwapOuterHTML.FocusScroll(true))
// [Output header]
// HX-Reswap: outerHTML focus-scroll:true

htmx.NewResponse().
  Reswap(htmx.SwapBeforeEnd.ScrollBottom())
// [Output header]
// HX-Reswap: beforeEnd scroll:bottom

htmx.NewResponse().
  Reswap(htmx.SwapInnerHTML.ShowTop("#another-div"))
// [Output header]
// HX-Reswap: innerHTML show:#another-div:top

[rafiramadhana]

@angelofallars is there anything that is expected to change beside the headers? (htmx.Response.Headers())

[rafiramadhana]

btw is it possible for the hx-swap to have more than one modifiers?

something like

// HX-Reswap: outerHTML focus-scroll:true scroll:bottom

[angelofallars]

btw is it possible for the hx-swap to have more than one modifiers?

something like

// HX-Reswap: outerHTML focus-scroll:true scroll:bottom

Yes, with method chaining:

htmx.SwapOuterHTML.FocusScroll(true).ScrollBottom()

[rafiramadhana]

Yes, with method chaining:

i see, i think the requirement is clear enough now

i will create a draft PR for #1

[rafiramadhana]

@angelofallars would you mind to check the draft PR? #3

it covers the proposal on how to set modifiers

but it has not covered all of the mentioned modifiers in https://htmx.org/attributes/hx-swap

the remaining modifiers will be covered once we agreed with the proposal

thanks!