Issue 2179 - [cms] Give Jinja2 templates a way to set global parameters

cms/converters.py

 # coding: utf-8
 
 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-2015 Eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
@@ skipping 266 matching lines @@
       code = self._params["source"].read_file(path)
       module = imp.new_module(root.replace("/", "."))
       exec code in module.__dict__
 
       func = os.path.basename(root)
       if not hasattr(module, func):
         raise Exception("Expected function %s not found in filter file %s" % (func, filename))
       filters[func] = getattr(module, func)
       filters[func].module_ref = module  # Prevent garbage collection
 
-    self._env = jinja2.Environment(
-        loader=self._SourceLoader(self._params["source"]),
-        extensions=["jinja2.ext.do",],
-        autoescape=True
-    )
+    self._env = jinja2.Environment(loader=self._SourceLoader(self._params["source"]), autoescape=True)
     self._env.filters.update(filters)
     self._env.globals.update(globals)
 
   def get_html(self, source):
     template = self._env.from_string(source)
-    return template.render(self._params, params=self._params)

[Sebastian Noack, 2015/03/20 09:44:36]

Note that modifying the params dict won't modify the current context. Hence
following template would output the old "title" passed to the template if any.

  {% do params.update(title="foo") %}
  ...
  {{ title }}

So how about:

  module = template.make_module(self._params)
  for key, value in module.__dict__.iteritems():
    if not key.startswith("_"):
      self._params[key] = value
  return unicode(module)

That way you can just keep using the regular {% set %} statement to set
variables. And variables set in the template will be copied to the self._params.

[Wladimir Palant, 2015/03/20 15:31:39]

The complication here: only variables set at top level will work. So setting
conditionally for example is extremely awkward. But - fine with me, I managed to
get it working.

I'm somewhat concerned about dumping every exported variable into self._params
but I don't see a better solution right now.

[Sebastian Noack, 2015/03/20 15:53:18]

I think it's the best we can realistically do.

+    module = template.make_module(self._params)
+    for key, value in module.__dict__.iteritems():
+      if not key.startswith("_"):
+        self._params[key] = value
+    return unicode(module)
 
   def translate(self, default, name, comment=None):
     # Note: We currently ignore the comment, it is only relevant when
     # generating the master translation.
     localedata = self._params["localedata"]
     return jinja2.Markup(self.localize_string(name, default, localedata, html_escapes))
 
   def get_string(self, name, page):
     localedata = self._params["source"].read_locale(self._params["locale"], page)
     default = localedata[name]
@@ skipping 28 matching lines @@
         stack.pop()
       stack[-1]["subitems"].append(item)
       stack.append(item)
     return structured
 
 converters = {
   "html": RawConverter,
   "md": MarkdownConverter,
   "tmpl": TemplateConverter,
 }