doc: add documentation for new trans with variable substitution

doc/developer-guide/translation.rst

@@ -48,9 +48,9 @@ Translate tag::
 
     {_ Translate me _}
 
-Extended translate tag::
+Interpolation trans tag::
 
-    {% _ "Example" nl="Voorbeeld" fr="Exemple" %}
+    {% trans "Hello {foo} World" foo=_"happy" %}
 
 As part of a tag parameter::
 

doc/ref/dispatch/dispatch_mod_import_csv-dispatch.rst

@@ -0,0 +1,4 @@
+
+.. include:: meta-mod_import_csv-dispatch.rst
+
+.. Not yet documented. (no todo item, as this is not a major issue)

doc/ref/tags/tag_trans.rst

@@ -13,7 +13,9 @@ Example::
 
    {_ translate me _}
 
-If the active language is “nl” then this will output “vertaal mij”.  Of course depending on the available translations. When a translation is not available then the text is output as-is without any translation.
+If the active language is “nl” then this will output “vertaal mij”.  Of course depending on the available translations.
 
-.. seealso:: :ref:`tag-_`.
+If a translation is not available then the text is output as-is without any translation.
+
+.. seealso:: :ref:`tag-trans_ext`.
 

doc/ref/tags/tag_trans_ext.rst

@@ -0,0 +1,27 @@
+
+.. index:: tag; translate
+.. _tag-trans_ext:
+
+translate with variable substitution
+====================================
+
+Translate a text value using gettext and substitute variables.
+
+Example::
+
+    {% trans "Hello {foo} World" foo=1234 %}
+
+This translates the text using the available po files. The variables in the translated text will
+be substituted with the value of the arguments.
+
+If the active language is “en” then the example above will output “Hello 1234 World”, in “nl” it will be “Hallo 1234 wereld”. Of course depending on the available translations. 
+
+If a translation is not available then the text is output as-is without any translation.
+
+If a “{” is needed in the string, then repeat it:
+
+    {% trans "Hello {{foo}}, and this is {foo}." foo=1234 %}
+
+Will echo “Hello {foo}, and this is 1234.”
+
+.. seealso:: :ref:`tag-trans`.

rebar.lock

@@ -135,7 +135,7 @@
   0},
  {<<"template_compiler">>,
   {git,"https://github.com/zotonic/template_compiler.git",
-       {ref,"f5c8e1827540f513ca1756cd06a9c98f52f21b92"}},
+       {ref,"14fae262a80340a5a4f10257ddb52fd943e783e5"}},
   0},
  {<<"twerl">>,
   {git,"https://github.com/mworrell/twerl.git",