Bindings

Bindings are the opposite of Server Side Includes (SSI). SSI is used when entire pages are written largely in EHTML and snippets of HTML, or more typically javascript code is inserted into the EHTML code.

Bindings are used the other way around. Essentially entire pages are written in regular HTML but parts of the HTML needs to be dynamically generated.

The yaws callback out/1 can return

      {bindings, [{Key1, Value2}, {Key2, Value2} .....]}.
    

All bindings can then be used in the rest of yaws code (in HTML source and within erl tags). In HTML source %%Key%% is expanded to Value and within erl tags yaws_api:get_binding(Key) can be used to extract Value.

With the binding feature it is easier to write transparent yaws code making it easier to to work together with Web people knowing little or nothing about Erlang.

An example:

<erl>
out(A) -> {bindings, [{"A", "foo"}, {"B", "baz"}]}.
</erl>

<html>
  <body>
    <p>%%A%%</p>
    <p><font size="4">%%A%% != %%B%%</font></p>
    <p>An enormous amount of plain html source here.</p>

<erl>
out(A) ->
    Value = yaws_api:binding("A"),
    {ehtml, {ul, [],
             [{li, [],
               Value},
              {li, [],
               "gazonk"}]}}.
</erl>

%%A%% = %%A%% (hit me)
</body>
</html>

Which expands to:


<html>
  <body>
    <p>foo</p>
    <p><font size="4">foo != baz</font></p>
    <p>An enormous amount of plain html source here.</p>

    <ul>
      <li>foo</li>
      <li>gazonk</li></ul>

foo = foo (hit me)

  </body>
</html>

And is rendered as:

foo

foo != baz

An enormous amount of plain html source here.

foo = foo (hit me)

Valid XHTML 1.0!