add index function in leader

src/rougail/template/base.py

@@ -169,6 +169,9 @@ class RougailLeader:
                 value = err
             self._follower[name].append(value)
 
+    def index(self, value):
+        return self._value.index(value)
+
 
 class RougailExtra:
     """Object that implement access to extra variable
@@ -310,6 +313,8 @@ class RougailBaseTemplate:
             destfilename = join(self.destinations_dir, true_destfilename[1:])
             makedirs(dirname(destfilename), exist_ok=True)
             self.log.info(_(f"{filevar['engine']} processing: '{destfilename}'"))
+            if isfile(destfilename):
+                raise TemplateError(_(f'destination file "{destfilename}" already exists'))
             self.engines[filevar['engine']].process(filename=filename,
                                                     source=source,
                                                     true_destfilename=true_destfilename,

tests/dictionaries/60extra_leadership_name/result/etc/mailname

@@ -9,3 +9,4 @@ testpre
 pretest
 leader2: test
 follower2: pre
+index: 0

tests/dictionaries/60extra_leadership_name/result/etc/mailname2

@@ -9,3 +9,4 @@ testpre
 pretest
 leader2: test
 follower2: pre
+index: 0

tests/dictionaries/60extra_leadership_name/tmpl/mailname

@@ -33,3 +33,4 @@ diff
 %end for
 leader2: %%extra.ejabberd.new_name.description[0].description
 follower2: %%extra.ejabberd.new_name.description[0].mode
+index: %%extra.ejabberd.new_name.description.index('test')

tests/dictionaries/60extra_leadership_name/tmpl/mailname2

@@ -31,3 +31,4 @@ diff
 {% endfor -%}
 leader2: {{ extra.ejabberd.new_name.description[0].description }}
 follower2: {{ extra.ejabberd.new_name.description[0].mode }}
+index: {{ extra.ejabberd.new_name.description.index('test') }}