I’ve been having fun getting familiar with Igniter for code generation and modification. Thanks for building and releasing it @zachdaniel !

Is there a suggested approach for modifying Heex code?

I have a scenario where I’d like to modify some of the Heex code that mix phx.new generates into core_components.ex. I’m working with Phoenix v1.8-rc.0, which makes notable changes to the core components compared with previous versions. See Chris McCord’s post for more details.

This default core_components.ex includes component markup inline with sigil_H heredocs, like this:

  def input(%{type: "select"} = assigns) do
    ~H"""
    <fieldset class="fieldset mb-2">
      <label>
        <span :if={@label} class="fieldset-label mb-1">{@label}</span>
        <select
          id={@id}
          name={@name}
          class={["w-full select", @errors != [] && "select-error"]}
          multiple={@multiple}
          {@rest}
        >
          <option :if={@prompt} value="">{@prompt}</option>
          {Phoenix.HTML.Form.options_for_select(@options, @value)}
        </select>
      </label>
      <.error :for={msg <- @errors}>{msg}</.error>
    </fieldset>
    """
  end

The AST represents the code inside the heredoc as a bitstring. I’ve tried several approaches, including simply replacing everything in the Heex block with what I want to be there, but Sourceror.parse_string/1 chokes on the first < in the string I pass to it. Does the existence of characters like < necessitate using a template to overwrite the file?

Thanks!