elixir-lang · josevalim · Mar 6, 2023 · Mar 3, 2023
diff --git a/README.md b/README.md
@@ -215,18 +215,57 @@ ExDoc renders Markdown content for you, but you can extend it to render complex
 ```elixir
 docs: [
   # ...
+  before_closing_head_tag: &before_closing_head_tag/1,
   before_closing_body_tag: &before_closing_body_tag/1
 ]
 
 # ...
 
+defp before_closing_head_tag(:html) do
+  """
+  <!-- HTML injected at the end of the <head> element -->
+  """
+end
+
+defp before_closing_head_tag(:epub), do: ""
+
 defp before_closing_body_tag(:html) do
   """
   <!-- HTML injected at the end of the <body> element -->
   """
 end
 
-defp before_closing_body_tag(_), do: ""
+defp before_closing_body_tag(:epub), do: ""
+```
+
+You could use `MFA` as well:
+
+```elixir
+docs: [
+  # ...
+  before_closing_head_tag: {MyModule, :before_closing_head_tag, ["Demo"]},
+  before_closing_body_tag: {MyModule, :before_closing_body_tag, ["Demo"]}
+]
+
+# ...
+
+defmodule MyModule do
+  def before_closing_head_tag(:html, name) do
+    # ...
+  end
+
+  def before_closing_head_tag(:epub, name) do
+    # ...
+  end
+
+  def before_closing_body_tag(:html, name) do
+    # ...
+  end
+
+  def before_closing_body_tag(:html, name) do
+    # ...
+  end
+end
 ```
 
 ### Rendering Math

diff --git a/lib/ex_doc/config.ex b/lib/ex_doc/config.ex
@@ -51,8 +51,8 @@ defmodule ExDoc.Config do
           apps: [atom()],
           assets: nil | String.t(),
           authors: nil | [String.t()],
-          before_closing_body_tag: (atom() -> String.t()),
-          before_closing_head_tag: (atom() -> String.t()),
+          before_closing_body_tag: (atom() -> String.t()) | mfa(),
+          before_closing_head_tag: (atom() -> String.t()) | mfa(),
           canonical: nil | String.t(),
           cover: nil | Path.t(),
           deps: [{ebin_path :: String.t(), doc_url :: String.t()}],

diff --git a/lib/ex_doc/formatter/epub/templates.ex b/lib/ex_doc/formatter/epub/templates.ex
@@ -3,6 +3,8 @@ defmodule ExDoc.Formatter.EPUB.Templates do
 
   require EEx
 
+  import ExDoc.Utils, only: [before_closing_body_tag: 2, before_closing_head_tag: 2]
+
   alias ExDoc.Formatter.HTML
   alias ExDoc.Formatter.HTML.Templates, as: H
 

diff --git a/lib/ex_doc/formatter/epub/templates/extra_template.eex b/lib/ex_doc/formatter/epub/templates/extra_template.eex
@@ -4,6 +4,6 @@
     </h1>
     <%= content %>
     <%# Extra content specified by the user (e.g. custom Javascript) %>
-    <%= config.before_closing_body_tag.(:epub) %>
+    <%= before_closing_body_tag(config, :epub) %>
   </body>
 </html>
diff --git a/lib/ex_doc/formatter/epub/templates/head_template.eex b/lib/ex_doc/formatter/epub/templates/head_template.eex
@@ -9,6 +9,6 @@
       href="<%= H.asset_rev "#{config.output}/OEBPS", "dist/epub-#{config.proglang}-*.css" %>" />
     <script src="<%= H.asset_rev "#{config.output}/OEBPS", "dist/epub-*.js" %>"></script>
     <%# Extra content specified by the user (e.g. custom CSS) %>
-    <%= config.before_closing_head_tag.(:epub) %>
+    <%= before_closing_head_tag(config, :epub) %>
   </head>
   <body class="content-inner">
diff --git a/lib/ex_doc/formatter/epub/templates/module_template.eex b/lib/ex_doc/formatter/epub/templates/module_template.eex
@@ -43,6 +43,6 @@
       </section>
     <% end %>
     <%# Extra content specified by the user (e.g. custom Javascript) %>
-    <%= config.before_closing_body_tag.(:epub) %>
+    <%= before_closing_body_tag(config, :epub) %>
   </body>
 </html>
diff --git a/lib/ex_doc/formatter/epub/templates/nav_template.eex b/lib/ex_doc/formatter/epub/templates/nav_template.eex
@@ -21,6 +21,6 @@
       </ol>
     </nav>
     <%# Extra content specified by the user (e.g. custom Javascript) %>
-    <%= config.before_closing_body_tag.(:epub) %>
+    <%= before_closing_body_tag(config, :epub) %>
   </body>
 </html>
diff --git a/lib/ex_doc/formatter/epub/templates/title_template.eex b/lib/ex_doc/formatter/epub/templates/title_template.eex
@@ -11,6 +11,6 @@
       <% end %>
     </div>
     <%# Extra content specified by the user (e.g. custom Javascript) %>
-    <%= config.before_closing_body_tag.(:epub) %>
+    <%= before_closing_body_tag(config, :epub) %>
   </body>
 </html>
diff --git a/lib/ex_doc/formatter/html/templates.ex b/lib/ex_doc/formatter/html/templates.ex
@@ -2,7 +2,7 @@ defmodule ExDoc.Formatter.HTML.Templates do
   @moduledoc false
   require EEx
 
-  import ExDoc.Utils, only: [h: 1]
+  import ExDoc.Utils, only: [h: 1, before_closing_body_tag: 2, before_closing_head_tag: 2]
 
   # TODO: It should not depend on the parent module. Move required HTML functions to Utils.
   # TODO: Add tests that assert on the returned structured, not on JSON

diff --git a/lib/ex_doc/formatter/html/templates/footer_template.eex b/lib/ex_doc/formatter/html/templates/footer_template.eex
@@ -40,6 +40,6 @@
 </section>
 </div>
   <%# Extra content specified by the user (e.g. custom Javascript) %>
-  <%= config.before_closing_body_tag.(:html) %>
+  <%= before_closing_body_tag(config, :html) %>
   </body>
 </html>
diff --git a/lib/ex_doc/formatter/html/templates/head_template.eex b/lib/ex_doc/formatter/html/templates/head_template.eex
@@ -25,7 +25,7 @@
     <% end %>
     <script async src="<%= asset_rev config.output, "dist/html-*.js" %>"></script>
     <%# Extra content specified by the user (e.g. custom CSS) %>
-    <%= config.before_closing_head_tag.(:html) %>
+    <%= before_closing_head_tag(config, :html) %>
   </head>
   <body data-type="<%= sidebar_type(page.type) %>" class="page-<%= page.type %>">
     <script>

diff --git a/lib/ex_doc/utils.ex b/lib/ex_doc/utils.ex
@@ -1,6 +1,28 @@
 defmodule ExDoc.Utils do
   @moduledoc false
 
+  @doc """
+  Runs the `before_closing_head_tag` callback.
+  """
+  def before_closing_head_tag(%{before_closing_head_tag: {m, f, a}}, module) do
+    apply(m, f, [module | a])
+  end
+
+  def before_closing_head_tag(%{before_closing_head_tag: before_closing_head_tag}, module) do
+    before_closing_head_tag.(module)
+  end
+
+  @doc """
+  Runs the `before_closing_body_tag` callback.
+  """
+  def before_closing_body_tag(%{before_closing_body_tag: {m, f, a}}, module) do
+    apply(m, f, [module | a])
+  end
+
+  def before_closing_body_tag(%{before_closing_body_tag: before_closing_body_tag}, module) do
+    before_closing_body_tag.(module)
+  end
+
   @doc """
   HTML escapes the given string.
 

diff --git a/test/ex_doc/formatter/epub_test.exs b/test/ex_doc/formatter/epub_test.exs
@@ -9,6 +9,9 @@ defmodule ExDoc.Formatter.EPUBTest do
   defp before_closing_head_tag(:epub), do: @before_closing_head_tag_content_epub
   defp before_closing_body_tag(:epub), do: @before_closing_body_tag_content_epub
 
+  def before_closing_head_tag(:epub, name), do: "<meta name=#{name}>"
+  def before_closing_body_tag(:epub, name), do: "<p>#{name}</p>"
+
   defp doc_config(%{tmp_dir: tmp_dir} = _context) do
     [
       app: :elixir,
@@ -188,6 +191,25 @@ defmodule ExDoc.Formatter.EPUBTest do
     end
   end
 
+  test "before_closing_*_tags required by the user are in the right place using MFA",
+       %{tmp_dir: tmp_dir} = context do
+    generate_docs_and_unzip(
+      context,
+      doc_config(context,
+        before_closing_head_tag: {__MODULE__, :before_closing_head_tag, ["Demo"]},
+        before_closing_body_tag: {__MODULE__, :before_closing_body_tag, ["Demo"]}
+      )
+    )
+
+    oebps_dir = tmp_dir <> "/epub/OEBPS"
+
+    for basename <- @example_basenames do
+      content = File.read!(Path.join(oebps_dir, basename))
+      assert content =~ ~r[<meta name=Demo>\s*</head>]
+      assert content =~ ~r[<p>Demo</p>\s*</body>]
+    end
+  end
+
   test "assets required by the user end up in the right place", %{tmp_dir: tmp_dir} = context do
     File.mkdir_p!("test/tmp/epub_assets/hello")
     File.touch!("test/tmp/epub_assets/hello/world.png")

diff --git a/test/ex_doc/formatter/html_test.exs b/test/ex_doc/formatter/html_test.exs
@@ -17,6 +17,9 @@ defmodule ExDoc.Formatter.HTMLTest do
   defp before_closing_head_tag(:html), do: @before_closing_head_tag_content_html
   defp before_closing_body_tag(:html), do: @before_closing_body_tag_content_html
 
+  def before_closing_head_tag(:html, name), do: "<meta name=#{name}>"
+  def before_closing_body_tag(:html, name), do: "<p>#{name}</p>"
+
   defp doc_config(%{tmp_dir: tmp_dir} = _context) do
     [
       apps: [:elixir],
@@ -548,6 +551,27 @@ defmodule ExDoc.Formatter.HTMLTest do
          %{
            tmp_dir: tmp_dir
          } = context do
+      generate_docs(
+        doc_config(context,
+          before_closing_head_tag: {__MODULE__, :before_closing_head_tag, ["Demo"]},
+          before_closing_body_tag: {__MODULE__, :before_closing_body_tag, ["Demo"]},
+          extras: ["test/fixtures/README.md"]
+        )
+      )
+
+      content = File.read!(tmp_dir <> "/html/api-reference.html")
+      assert content =~ ~r[<meta name=Demo>\s*</head>]
+      assert content =~ ~r[<p>Demo</p>\s*</body>]
+
+      content = File.read!(tmp_dir <> "/html/readme.html")
+      assert content =~ ~r[<meta name=Demo>\s*</head>]
+      assert content =~ ~r[<p>Demo</p>\s*</body>]
+    end
+
+    test "before_closing_*_tags required by the user are placed in the right place using MFA",
+         %{
+           tmp_dir: tmp_dir
+         } = context do
       generate_docs(
         doc_config(context,
           before_closing_head_tag: &before_closing_head_tag/1,