diff --git a/jinja2/environment.py b/jinja2/environment.py
index 9807184..fa19b1b 100644
--- a/jinja2/environment.py
+++ b/jinja2/environment.py
@@ -23,7 +23,7 @@
 _spontaneous_environments = LRUCache(10)
 
 
-def _get_spontaneous_environment(*args):
+def get_spontaneous_environment(*args):
     """Return a new spontaneus environment.  A spontaneus environment is an
     unnamed and unaccessable (in theory) environment that is used for
     template generated from a string and not from the file system.
@@ -85,11 +85,21 @@
                  comment_end_string='#}',
                  line_statement_prefix=None,
                  trim_blocks=False,
+                 extensions=(),
                  optimized=True,
                  undefined=Undefined,
-                 loader=None,
-                 extensions=(),
-                 finalize=unicode):
+                 finalize=unicode,
+                 loader=None):
+        # !!Important notice!!
+        #   The constructor accepts quite a few arguments that should be
+        #   passed by keyword rather than position.  However it's important to
+        #   not change the order of arguments because it's used at least
+        #   internally in those cases:
+        #       -   spontaneus environments (i18n extension and Template)
+        #       -   unittests
+        #   If parameter changes are required only add parameters at the end
+        #   and don't change the arguments (or the defaults!) of the arguments
+        #   up to (but excluding) loader.
         """Here the possible initialization parameters:
 
         ========================= ============================================
@@ -109,15 +119,15 @@
         `trim_blocks`             If this is set to ``True`` the first newline
                                   after a block is removed (block, not
                                   variable tag!). Defaults to ``False``.
+        `extensions`              List of Jinja extensions to use.
         `optimized`               should the optimizer be enabled?  Default is
                                   ``True``.
         `undefined`               a subclass of `Undefined` that is used to
                                   represent undefined variables.
-        `loader`                  the loader which should be used.
-        `extensions`              List of Jinja extensions to use.
         `finalize`                A callable that finalizes the variable.  Per
                                   default this is `unicode`, other useful
                                   builtin finalizers are `escape`.
+        `loader`                  the loader which should be used.
         ========================= ============================================
         """
 
@@ -138,14 +148,6 @@
         self.line_statement_prefix = line_statement_prefix
         self.trim_blocks = trim_blocks
 
-        # load extensions
-        self.extensions = []
-        for extension in extensions:
-            if isinstance(extension, basestring):
-                extension = import_string(extension)
-            # extensions are instanciated early but initalized later.
-            self.extensions.append(object.__new__(extension))
-
         # runtime information
         self.undefined = undefined
         self.optimized = optimized
@@ -162,9 +164,12 @@
         # create lexer
         self.lexer = Lexer(self)
 
-        # initialize extensions
-        for extension in self.extensions:
-            extension.__init__(self)
+        # load extensions
+        self.extensions = []
+        for extension in extensions:
+            if isinstance(extension, basestring):
+                extension = import_string(extension)
+            self.extensions.append(extension(self))
 
     def subscribe(self, obj, argument):
         """Get an item or attribute of an object."""
@@ -282,17 +287,15 @@
                 comment_end_string='#}',
                 line_statement_prefix=None,
                 trim_blocks=False,
+                extensions=(),
                 optimized=True,
                 undefined=Undefined,
-                extensions=(),
                 finalize=unicode):
-        # make sure extensions are hashable
-        extensions = tuple(extensions)
-        env = _get_spontaneous_environment(
+        env = get_spontaneous_environment(
             block_start_string, block_end_string, variable_start_string,
             variable_end_string, comment_start_string, comment_end_string,
-            line_statement_prefix, trim_blocks, optimized, undefined,
-            None, extensions, finalize)
+            line_statement_prefix, trim_blocks, tuple(extensions), optimized,
+            undefined, finalize)
         return env.from_string(source, template_class=cls)
 
     def render(self, *args, **kwargs):
@@ -402,11 +405,9 @@
 
             while 1:
                 try:
-                    while 1:
+                    while c_size < size:
                         push(next())
                         c_size += 1
-                        if c_size >= size:
-                            raise StopIteration()
                 except StopIteration:
                     if not c_size:
                         raise
diff --git a/jinja2/ext.py b/jinja2/ext.py
index acce835..2c61bb0 100644
--- a/jinja2/ext.py
+++ b/jinja2/ext.py
@@ -3,17 +3,26 @@
     jinja2.ext
     ~~~~~~~~~~
 
-    Jinja extensions (EXPERIMENAL)
-
-    The plan: i18n and caching becomes a parser extension. cache/endcache
-    as well as trans/endtrans are not keyword and don't have nodes but
-    translate into regular jinja nodes so that the person who writes such
-    custom tags doesn't have to generate python code himself.
+    Jinja extensions allow to add custom tags similar to the way django custom
+    tags work.  By default two example extensions exist: an i18n and a cache
+    extension.
 
     :copyright: Copyright 2008 by Armin Ronacher.
     :license: BSD.
 """
+from collections import deque
 from jinja2 import nodes
+from jinja2.environment import get_spontaneous_environment
+from jinja2.runtime import Undefined
+from jinja2.parser import statement_end_tokens
+from jinja2.exceptions import TemplateAssertionError
+from jinja2.utils import import_string
+
+
+# the only real useful gettext functions for a Jinja template.  Note
+# that ugettext must be assigned to gettext as Jinja doesn't support
+# non unicode strings.
+GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext')
 
 
 class Extension(object):
@@ -51,3 +60,235 @@
             nodes.Call(nodes.Name('cache_support', 'load'), args, [], None, None),
             [], [], body
         )
+
+
+class TransExtension(Extension):
+    """This extension adds gettext support to Jinja."""
+    tags = set(['trans'])
+
+    def __init__(self, environment):
+        Extension.__init__(self, environment)
+        environment.globals.update({
+            '_':        lambda x: x,
+            'gettext':  lambda x: x,
+            'ngettext': lambda s, p, n: (s, p)[n != 1]
+        })
+
+    def parse(self, parser):
+        """Parse a translatable tag."""
+        lineno = parser.stream.next().lineno
+
+        # skip colon for python compatibility
+        if parser.stream.current.type is 'colon':
+            parser.stream.next()
+
+        # find all the variables referenced.  Additionally a variable can be
+        # defined in the body of the trans block too, but this is checked at
+        # a later state.
+        plural_expr = None
+        variables = {}
+        while parser.stream.current.type is not 'block_end':
+            if variables:
+                parser.stream.expect('comma')
+            name = parser.stream.expect('name')
+            if name.value in variables:
+                raise TemplateAssertionError('translatable variable %r defined '
+                                             'twice.' % name.value, name.lineno,
+                                             parser.filename)
+
+            # expressions
+            if parser.stream.current.type is 'assign':
+                parser.stream.next()
+                variables[name.value] = var = parser.parse_expression()
+            else:
+                variables[name.value] = var = nodes.Name(name.value, 'load')
+            if plural_expr is None:
+                plural_expr = var
+        parser.stream.expect('block_end')
+
+        plural = plural_names = None
+        have_plural = False
+        referenced = set()
+
+        # now parse until endtrans or pluralize
+        singular_names, singular = self._parse_block(parser, True)
+        if singular_names:
+            referenced.update(singular_names)
+            if plural_expr is None:
+                plural_expr = nodes.Name(singular_names[0], 'load')
+
+        # if we have a pluralize block, we parse that too
+        if parser.stream.current.test('name:pluralize'):
+            have_plural = True
+            parser.stream.next()
+            if parser.stream.current.type is not 'block_end':
+                plural_expr = parser.parse_expression()
+            parser.stream.expect('block_end')
+            plural_names, plural = self._parse_block(parser, False)
+            parser.stream.next()
+            referenced.update(plural_names)
+        else:
+            parser.stream.next()
+
+        # register free names as simple name expressions
+        for var in referenced:
+            if var not in variables:
+                variables[var] = nodes.Name(var, 'load')
+
+        # no variables referenced?  no need to escape
+        if not referenced:
+            singular = singular.replace('%%', '%')
+            if plural:
+                plural = plural.replace('%%', '%')
+
+        if not have_plural:
+            plural_expr = None
+        elif plural_expr is None:
+            raise TemplateAssertionError('pluralize without variables',
+                                         lineno, parser.filename)
+
+        if variables:
+            variables = nodes.Dict([nodes.Pair(nodes.Const(x, lineno=lineno), y)
+                                    for x, y in variables.items()])
+        else:
+            variables = None
+
+        node = self._make_node(singular, plural, variables, plural_expr)
+        node.set_lineno(lineno)
+        return node
+
+    def _parse_block(self, parser, allow_pluralize):
+        """Parse until the next block tag with a given name."""
+        referenced = []
+        buf = []
+        while 1:
+            if parser.stream.current.type is 'data':
+                buf.append(parser.stream.current.value.replace('%', '%%'))
+                parser.stream.next()
+            elif parser.stream.current.type is 'variable_begin':
+                parser.stream.next()
+                name = parser.stream.expect('name').value
+                referenced.append(name)
+                buf.append('%%(%s)s' % name)
+                parser.stream.expect('variable_end')
+            elif parser.stream.current.type is 'block_begin':
+                parser.stream.next()
+                if parser.stream.current.test('name:endtrans'):
+                    break
+                elif parser.stream.current.test('name:pluralize'):
+                    if allow_pluralize:
+                        break
+                    raise TemplateSyntaxError('a translatable section can '
+                                              'have only one pluralize '
+                                              'section',
+                                              parser.stream.current.lineno,
+                                              parser.filename)
+                raise TemplateSyntaxError('control structures in translatable'
+                                          ' sections are not allowed.',
+                                          parser.stream.current.lineno,
+                                          parser.filename)
+            else:
+                assert False, 'internal parser error'
+
+        return referenced, u''.join(buf)
+
+    def _make_node(self, singular, plural, variables, plural_expr):
+        """Generates a useful node from the data provided."""
+        # singular only:
+        if plural_expr is None:
+            gettext = nodes.Name('gettext', 'load')
+            node = nodes.Call(gettext, [nodes.Const(singular)],
+                              [], None, None)
+            if variables:
+                node = nodes.Mod(node, variables)
+
+        # singular and plural
+        else:
+            ngettext = nodes.Name('ngettext', 'load')
+            node = nodes.Call(ngettext, [
+                nodes.Const(singular),
+                nodes.Const(plural),
+                plural_expr
+            ], [], None, None)
+            if variables:
+                node = nodes.Mod(node, variables)
+        return nodes.Output([node])
+
+
+def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS):
+    """Extract localizable strings from the given template node.
+
+    For every string found this function yields a ``(lineno, function,
+    message)`` tuple, where:
+
+    * ``lineno`` is the number of the line on which the string was found,
+    * ``function`` is the name of the ``gettext`` function used (if the
+      string was extracted from embedded Python code), and
+    *  ``message`` is the string itself (a ``unicode`` object, or a tuple
+       of ``unicode`` objects for functions with multiple string arguments).
+    """
+    for node in node.find_all(nodes.Call):
+        if not isinstance(node.node, nodes.Name) or \
+           node.node.name not in gettext_functions:
+            continue
+
+        strings = []
+        for arg in node.args:
+            if isinstance(arg, nodes.Const) and \
+               isinstance(arg.value, basestring):
+                strings.append(arg.value)
+            else:
+                strings.append(None)
+
+        if len(strings) == 1:
+            strings = strings[0]
+        else:
+            strings = tuple(strings)
+        yield node.lineno, node.node.name, strings
+
+
+def babel_extract(fileobj, keywords, comment_tags, options):
+    """Babel extraction method for Jinja templates.
+
+    :param fileobj: the file-like object the messages should be extracted from
+    :param keywords: a list of keywords (i.e. function names) that should be
+                     recognized as translation functions
+    :param comment_tags: a list of translator tags to search for and include
+                         in the results.  (Unused)
+    :param options: a dictionary of additional options (optional)
+    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
+             (comments will be empty currently)
+    """
+    encoding = options.get('encoding', 'utf-8')
+
+    have_trans_extension = False
+    extensions = []
+    for extension in options.get('extensions', '').split(','):
+        extension = extension.strip()
+        if not extension:
+            continue
+        extension = import_string(extension)
+        if extension is TransExtension:
+            have_trans_extension = True
+        extensions.append(extension)
+    if not have_trans_extension:
+        extensions.append(TransExtension)
+
+    environment = get_spontaneous_environment(
+        options.get('block_start_string', '{%'),
+        options.get('block_end_string', '%}'),
+        options.get('variable_start_string', '{{'),
+        options.get('variable_end_string', '}}'),
+        options.get('comment_start_string', '{#'),
+        options.get('comment_end_string', '#}'),
+        options.get('line_statement_prefix') or None,
+        options.get('trim_blocks', '').lower() in ('1', 'on', 'yes', 'true'),
+        tuple(extensions),
+        # fill with defaults so that environments are shared
+        # with other spontaneus environments.
+        True, Undefined, unicode
+    )
+
+    node = environment.parse(fileobj.read().decode(encoding))
+    for lineno, func, message in extract_from_ast(node, keywords):
+        yield lineno, func, message, []
diff --git a/jinja2/i18n.py b/jinja2/i18n.py
deleted file mode 100644
index 6718962..0000000
--- a/jinja2/i18n.py
+++ /dev/null
@@ -1,246 +0,0 @@
-# -*- coding: utf-8 -*-
-"""
-    jinja2.i18n
-    ~~~~~~~~~~~
-
-    i18n support for Jinja.
-
-    :copyright: Copyright 2008 by Armin Ronacher.
-    :license: BSD.
-"""
-from collections import deque
-from jinja2 import nodes
-from jinja2.environment import Environment
-from jinja2.parser import statement_end_tokens
-from jinja2.ext import Extension
-from jinja2.exceptions import TemplateAssertionError
-
-
-# the only real useful gettext functions for a Jinja template.  Note
-# that ugettext must be assigned to gettext as Jinja doesn't support
-# non unicode strings.
-GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext')
-
-
-def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS):
-    """Extract localizable strings from the given template node.
-
-    For every string found this function yields a ``(lineno, function,
-    message)`` tuple, where:
-
-    * ``lineno`` is the number of the line on which the string was found,
-    * ``function`` is the name of the ``gettext`` function used (if the
-      string was extracted from embedded Python code), and
-    *  ``message`` is the string itself (a ``unicode`` object, or a tuple
-       of ``unicode`` objects for functions with multiple string arguments).
-    """
-    for node in node.find_all(nodes.Call):
-        if not isinstance(node.node, nodes.Name) or \
-           node.node.name not in gettext_functions:
-            continue
-
-        strings = []
-        for arg in node.args:
-            if isinstance(arg, nodes.Const) and \
-               isinstance(arg.value, basestring):
-                strings.append(arg.value)
-            else:
-                strings.append(None)
-
-        if len(strings) == 1:
-            strings = strings[0]
-        else:
-            strings = tuple(strings)
-        yield node.lineno, node.node.name, strings
-
-
-def babel_extract(fileobj, keywords, comment_tags, options):
-    """Babel extraction method for Jinja templates.
-
-    :param fileobj: the file-like object the messages should be extracted from
-    :param keywords: a list of keywords (i.e. function names) that should be
-                     recognized as translation functions
-    :param comment_tags: a list of translator tags to search for and include
-                         in the results.  (Unused)
-    :param options: a dictionary of additional options (optional)
-    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
-             (comments will be empty currently)
-    """
-    encoding = options.get('encoding', 'utf-8')
-    extensions = [x.strip() for x in options.get('extensions', '').split(',')]
-    environment = Environment(
-        options.get('block_start_string', '{%'),
-        options.get('block_end_string', '%}'),
-        options.get('variable_start_string', '{{'),
-        options.get('variable_end_string', '}}'),
-        options.get('comment_start_string', '{#'),
-        options.get('comment_end_string', '#}'),
-        options.get('line_statement_prefix') or None,
-        options.get('trim_blocks', '').lower() in ('1', 'on', 'yes', 'true'),
-        extensions=[x for x in extensions if x]
-    )
-
-    # add the i18n extension only if it's not yet in the list.  Some people
-    # might use a script to sync the babel ini with the Jinja configuration
-    # so we want to avoid having the trans extension twice in the list.
-    for extension in environment.extensions:
-        if isinstance(extension, TransExtension):
-            break
-    else:
-        environment.extensions.append(TransExtension(environment))
-
-    node = environment.parse(fileobj.read().decode(encoding))
-    for lineno, func, message in extract_from_ast(node, keywords):
-        yield lineno, func, message, []
-
-
-class TransExtension(Extension):
-    tags = set(['trans'])
-
-    def __init__(self, environment):
-        Extension.__init__(self, environment)
-        environment.globals.update({
-            '_':        lambda x: x,
-            'gettext':  lambda x: x,
-            'ngettext': lambda s, p, n: (s, p)[n != 1]
-        })
-
-    def parse(self, parser):
-        """Parse a translatable tag."""
-        lineno = parser.stream.next().lineno
-
-        # skip colon for python compatibility
-        if parser.stream.current.type is 'colon':
-            parser.stream.next()
-
-        # find all the variables referenced.  Additionally a variable can be
-        # defined in the body of the trans block too, but this is checked at
-        # a later state.
-        plural_expr = None
-        variables = {}
-        while parser.stream.current.type is not 'block_end':
-            if variables:
-                parser.stream.expect('comma')
-            name = parser.stream.expect('name')
-            if name.value in variables:
-                raise TemplateAssertionError('translatable variable %r defined '
-                                             'twice.' % name.value, name.lineno,
-                                             parser.filename)
-
-            # expressions
-            if parser.stream.current.type is 'assign':
-                parser.stream.next()
-                variables[name.value] = var = parser.parse_expression()
-            else:
-                variables[name.value] = var = nodes.Name(name.value, 'load')
-            if plural_expr is None:
-                plural_expr = var
-        parser.stream.expect('block_end')
-
-        plural = plural_names = None
-        have_plural = False
-        referenced = set()
-
-        # now parse until endtrans or pluralize
-        singular_names, singular = self._parse_block(parser, True)
-        if singular_names:
-            referenced.update(singular_names)
-            if plural_expr is None:
-                plural_expr = nodes.Name(singular_names[0], 'load')
-
-        # if we have a pluralize block, we parse that too
-        if parser.stream.current.test('name:pluralize'):
-            have_plural = True
-            parser.stream.next()
-            if parser.stream.current.type is not 'block_end':
-                plural_expr = parser.parse_expression()
-            parser.stream.expect('block_end')
-            plural_names, plural = self._parse_block(parser, False)
-            parser.stream.next()
-            referenced.update(plural_names)
-        else:
-            parser.stream.next()
-
-        # register free names as simple name expressions
-        for var in referenced:
-            if var not in variables:
-                variables[var] = nodes.Name(var, 'load')
-
-        # no variables referenced?  no need to escape
-        if not referenced:
-            singular = singular.replace('%%', '%')
-            if plural:
-                plural = plural.replace('%%', '%')
-
-        if not have_plural:
-            plural_expr = None
-        elif plural_expr is None:
-            raise TemplateAssertionError('pluralize without variables',
-                                         lineno, parser.filename)
-
-        if variables:
-            variables = nodes.Dict([nodes.Pair(nodes.Const(x, lineno=lineno), y)
-                                    for x, y in variables.items()])
-        else:
-            variables = None
-
-        node = self._make_node(singular, plural, variables, plural_expr)
-        node.set_lineno(lineno)
-        return node
-
-    def _parse_block(self, parser, allow_pluralize):
-        """Parse until the next block tag with a given name."""
-        referenced = []
-        buf = []
-        while 1:
-            if parser.stream.current.type is 'data':
-                buf.append(parser.stream.current.value.replace('%', '%%'))
-                parser.stream.next()
-            elif parser.stream.current.type is 'variable_begin':
-                parser.stream.next()
-                name = parser.stream.expect('name').value
-                referenced.append(name)
-                buf.append('%%(%s)s' % name)
-                parser.stream.expect('variable_end')
-            elif parser.stream.current.type is 'block_begin':
-                parser.stream.next()
-                if parser.stream.current.test('name:endtrans'):
-                    break
-                elif parser.stream.current.test('name:pluralize'):
-                    if allow_pluralize:
-                        break
-                    raise TemplateSyntaxError('a translatable section can '
-                                              'have only one pluralize '
-                                              'section',
-                                              parser.stream.current.lineno,
-                                              parser.filename)
-                raise TemplateSyntaxError('control structures in translatable'
-                                          ' sections are not allowed.',
-                                          parser.stream.current.lineno,
-                                          parser.filename)
-            else:
-                assert False, 'internal parser error'
-
-        return referenced, u''.join(buf)
-
-    def _make_node(self, singular, plural, variables, plural_expr):
-        """Generates a useful node from the data provided."""
-        # singular only:
-        if plural_expr is None:
-            gettext = nodes.Name('gettext', 'load')
-            node = nodes.Call(gettext, [nodes.Const(singular)],
-                              [], None, None)
-            if variables:
-                node = nodes.Mod(node, variables)
-
-        # singular and plural
-        else:
-            ngettext = nodes.Name('ngettext', 'load')
-            node = nodes.Call(ngettext, [
-                nodes.Const(singular),
-                nodes.Const(plural),
-                plural_expr
-            ], [], None, None)
-            if variables:
-                node = nodes.Mod(node, variables)
-        return nodes.Output([node])
diff --git a/jinja2/lexer.py b/jinja2/lexer.py
index 5576ac1..5217c7d 100644
--- a/jinja2/lexer.py
+++ b/jinja2/lexer.py
@@ -18,13 +18,12 @@
 import unicodedata
 from jinja2.datastructure import TokenStream, Token
 from jinja2.exceptions import TemplateSyntaxError
-from weakref import WeakValueDictionary
+from jinja2.utils import LRUCache
 
 
 # cache for the lexers. Exists in order to be able to have multiple
 # environments with the same lexer
-_lexer_cache = WeakValueDictionary()
-
+_lexer_cache = LRUCache(10)
 
 # static regular expressions
 whitespace_re = re.compile(r'\s+(?um)')
@@ -34,7 +33,6 @@
 name_re = re.compile(r'\b[a-zA-Z_][a-zA-Z0-9_]*\b')
 float_re = re.compile(r'\d+\.\d+')
 
-
 # set of used keywords
 keywords = set(['and', 'block', 'elif', 'else', 'endblock', 'print',
                 'endfilter', 'endfor', 'endif', 'endmacro', 'endraw',
@@ -96,80 +94,20 @@
 
 
 def unescape_string(lineno, filename, s):
-    r"""
-    Unescape a string. Supported escapes:
+    r"""Unescape a string. Supported escapes:
         \a, \n, \r\, \f, \v, \\, \", \', \0
 
         \x00, \u0000, \U00000000, \N{...}
-
-    Not supported are \101 because imho redundant.
     """
-    result = []
-    write = result.append
-    chariter = iter(s)
-    next_char = chariter.next
-
-    # faster lookup
-    sescapes = simple_escapes
-    uescapes = unicode_escapes
-
     try:
-        for char in chariter:
-            if char == '\\':
-                char = next_char()
-                if char in sescapes:
-                    write(sescapes[char])
-                elif char in uescapes:
-                    seq = [next_char() for x in xrange(uescapes[char])]
-                    try:
-                        write(unichr(int(''.join(seq), 16)))
-                    except ValueError:
-                        raise TemplateSyntaxError('invalid unicode codepoint',
-                                                  lineno, filename)
-                elif char == 'N':
-                    if next_char() != '{':
-                        raise TemplateSyntaxError('no name for codepoint',
-                                                  lineno, filename)
-                    seq = []
-                    while 1:
-                        char = next_char()
-                        if char == '}':
-                            break
-                        seq.append(char)
-                    try:
-                        write(unicodedata.lookup(u''.join(seq)))
-                    except KeyError:
-                        raise TemplateSyntaxError('unknown character name',
-                                                  lineno, filename)
-                else:
-                    write('\\' + char)
-            else:
-                write(char)
-    except StopIteration:
-        raise TemplateSyntaxError('invalid string escape', lineno, filename)
-    return u''.join(result)
-
-
-def unescape_regex(s):
-    """
-    Unescape rules for regular expressions.
-    """
-    buffer = []
-    write = buffer.append
-    in_escape = False
-    for char in s:
-        if in_escape:
-            in_escape = False
-            if char not in safe_chars:
-                write('\\' + char)
-                continue
-        write(char)
-    return u''.join(buffer)
+        return s.encode('ascii', 'backslashreplace').decode('unicode-escape')
+    except UnicodeError, e:
+        msg = str(e).split(':')[-1].strip()
+        raise TemplateSyntaxError(msg, lineno, filename)
 
 
 class Failure(object):
-    """
-    Class that raises a `TemplateSyntaxError` if called.
+    """Class that raises a `TemplateSyntaxError` if called.
     Used by the `Lexer` to specify known errors.
     """
 
@@ -182,8 +120,7 @@
 
 
 class LexerMeta(type):
-    """
-    Metaclass for the lexer that caches instances for
+    """Metaclass for the lexer that caches instances for
     the same configuration in a weak value dictionary.
     """
 
@@ -196,20 +133,15 @@
                environment.comment_end_string,
                environment.line_statement_prefix,
                environment.trim_blocks)
-
-        # use the cached lexer if possible
-        if key in _lexer_cache:
-            return _lexer_cache[key]
-
-        # create a new lexer and cache it
-        lexer = type.__call__(cls, environment)
-        _lexer_cache[key] = lexer
+        lexer = _lexer_cache.get(key)
+        if lexer is None:
+            lexer = type.__call__(cls, environment)
+            _lexer_cache[key] = lexer
         return lexer
 
 
 class Lexer(object):
-    """
-    Class that implements a lexer for a given environment. Automatically
+    """Class that implements a lexer for a given environment. Automatically
     created by the environment class, usually you don't have to do that.
 
     Note that the lexer is not automatically bound to an environment.
@@ -362,12 +294,11 @@
         return TokenStream(generate(), filename)
 
     def tokeniter(self, source, filename=None):
-        """
-        This method tokenizes the text and returns the tokens in a generator.
-        Use this method if you just want to tokenize a template. The output
-        you get is not compatible with the input the jinja parser wants. The
-        parser uses the `tokenize` function with returns a `TokenStream` and
-        keywords instead of just names.
+        """This method tokenizes the text and returns the tokens in a
+        generator.  Use this method if you just want to tokenize a template.
+        The output you get is not compatible with the input the jinja parser
+        wants.  The parser uses the `tokenize` function with returns a
+        `TokenStream` and postprocessed tokens.
         """
         source = '\n'.join(source.splitlines())
         pos = 0
diff --git a/jinja2/nodes.py b/jinja2/nodes.py
index 62686c4..5f3aabb 100644
--- a/jinja2/nodes.py
+++ b/jinja2/nodes.py
@@ -42,8 +42,8 @@
     'gteq':     operator.ge,
     'lt':       operator.lt,
     'lteq':     operator.le,
-    'in':       operator.contains,
-    'notin':    lambda a, b: b not in a
+    'in':       lambda a, b: a in b,
+    'notin':    lambda a, b: a not in b
 }
 
 
@@ -518,10 +518,13 @@
 
     def as_const(self):
         result = value = self.expr.as_const()
-        for op in self.ops:
-            new_value = op.expr.as_const()
-            result = _cmpop_to_func[op.op](value, new_value)
-            value = new_value
+        try:
+            for op in self.ops:
+                new_value = op.expr.as_const()
+                result = _cmpop_to_func[op.op](value, new_value)
+                value = new_value
+        except:
+            raise Impossible()
         return result
 
 
diff --git a/jinja2/parser.py b/jinja2/parser.py
index 5658ca9..8db62de 100644
--- a/jinja2/parser.py
+++ b/jinja2/parser.py
@@ -17,6 +17,7 @@
                                  'macro', 'include'])
 _compare_operators = frozenset(['eq', 'ne', 'lt', 'lteq', 'gt', 'gteq', 'in'])
 statement_end_tokens = set(['variable_end', 'block_end', 'in'])
+_tuple_edge_tokens = set(['rparen']) | statement_end_tokens
 
 
 class Parser(object):
@@ -421,12 +422,13 @@
         while 1:
             if args:
                 self.stream.expect('comma')
-            if self.stream.current.type in statement_end_tokens:
+            if self.stream.current.type in _tuple_edge_tokens:
                 break
             args.append(parse())
-            if self.stream.current.type is not 'comma':
+            if self.stream.current.type is 'comma':
+                is_tuple = True
+            else:
                 break
-            is_tuple = True
             lineno = self.stream.current.lineno
         if not is_tuple and args:
             if enforce:
@@ -640,12 +642,7 @@
                 self.stream.next()
             elif token.type is 'variable_begin':
                 self.stream.next()
-                want_comma = False
-                while not self.stream.current.test_many(statement_end_tokens):
-                    if want_comma:
-                        self.stream.expect('comma')
-                    add_data(self.parse_expression())
-                    want_comma = True
+                add_data(self.parse_tuple())
                 self.stream.expect('variable_end')
             elif token.type is 'block_begin':
                 flush_data()
diff --git a/jinja2/runtime.py b/jinja2/runtime.py
index 9018d52..0c0458c 100644
--- a/jinja2/runtime.py
+++ b/jinja2/runtime.py
@@ -35,9 +35,9 @@
         for name, obj in self.parent.iteritems():
             if type(obj) is FunctionType:
                 if getattr(obj, 'contextfunction', 0):
-                    self.vars[key] = partial(obj, self)
+                    self.vars[name] = partial(obj, self)
                 elif getattr(obj, 'environmentfunction', 0):
-                    self.vars[key] = partial(obj, environment)
+                    self.vars[name] = partial(obj, environment)
 
         # create the initial mapping of blocks.  Whenever template inheritance
         # takes place the runtime will update this mapping with the new blocks
@@ -56,6 +56,13 @@
                                               'called %r.' % block)
         return SuperBlock(block, self, last)
 
+    def get(self, name, default=None):
+        """For dict compatibility"""
+        try:
+            return self[name]
+        except KeyError:
+            return default
+
     def update(self, mapping):
         """Update vars from a mapping but don't export them."""
         self.vars.update(mapping)
@@ -76,6 +83,9 @@
         self.vars[key] = value
         self.exported_vars.add(key)
 
+    def __contains__(self, name):
+        return name in self.vars or name in self.parent
+
     def __getitem__(self, key):
         if key in self.vars:
             return self.vars[key]
diff --git a/setup.py b/setup.py
index 7ba463a..0c4fb31 100644
--- a/setup.py
+++ b/setup.py
@@ -134,6 +134,6 @@
     extras_require={'i18n': ['Babel>=0.8']},
     entry_points="""
     [babel.extractors]
-    jinja2 = jinja.i18n:babel_extract[i18n]
+    jinja2 = jinja.ext:babel_extract[i18n]
     """
 )
diff --git a/tests/test_i18n.py b/tests/test_i18n.py
index 0d00973..d405c9c 100644
--- a/tests/test_i18n.py
+++ b/tests/test_i18n.py
@@ -46,7 +46,7 @@
 
 i18n_env = Environment(
     loader=DictLoader(templates),
-    extensions=['jinja2.i18n.TransExtension']
+    extensions=['jinja2.ext.TransExtension']
 )
 i18n_env.globals.update({
     '_':            gettext,
@@ -72,7 +72,7 @@
 
 
 def test_extract():
-    from jinja2.i18n import babel_extract
+    from jinja2.ext import babel_extract
     from StringIO import StringIO
     source = StringIO('''
     {{ gettext('Hello World') }}
@@ -80,7 +80,7 @@
     {% trans %}{{ users }} user{% pluralize %}{{ users }} users{% endtrans %}
     ''')
     assert list(babel_extract(source, ('gettext', 'ngettext', '_'), [], {})) == [
-        (2, 'gettext', 'Hello World', []),
+        (2, 'gettext', u'Hello World', []),
         (3, 'gettext', u'Hello World', []),
         (4, 'ngettext', (u'%(users)s user', u'%(users)s users', None), [])
     ]
diff --git a/tests/test_macros.py b/tests/test_macros.py
index 5cf6f6d..f227788 100644
--- a/tests/test_macros.py
+++ b/tests/test_macros.py
@@ -8,44 +8,34 @@
 """
 
 SIMPLE = '''\
-{% macro say_hello name %}Hello {{ name }}!{% endmacro %}
+{% macro say_hello(name) %}Hello {{ name }}!{% endmacro %}
 {{ say_hello('Peter') }}\
 '''
 
-KWARGSFAILURE = '''\
-{% macro foo bar %}...{% endmacro %}
-{{ foo(bar='blub') }}\
-'''
-
 SCOPING = '''\
-{% macro level1 data1 %}
-{% macro level2 data2 %}{{ data1 }}|{{ data2 }}{% endmacro %}
+{% macro level1(data1) %}
+{% macro level2(data2) %}{{ data1 }}|{{ data2 }}{% endmacro %}
 {{ level2('bar') }}{% endmacro %}
 {{ level1('foo') }}|{{ level2('bar') }}\
 '''
 
 ARGUMENTS = '''\
-{% macro m a, b, c='c', d='d' %}{{ a }}|{{ b }}|{{ c }}|{{ d }}{% endmacro %}
+{% macro m(a, b, c='c', d='d') %}{{ a }}|{{ b }}|{{ c }}|{{ d }}{% endmacro %}
 {{ m() }}|{{ m('a') }}|{{ m('a', 'b') }}|{{ m(1, 2, 3) }}\
 '''
 
-PARENTHESES = '''\
-{% macro foo(a, b) %}{{ a }}|{{ b }}{% endmacro %}\
-{{ foo(1, 2) }}\
-'''
-
 VARARGS = '''\
-{% macro test %}{{ varargs|join('|') }}{% endmacro %}\
+{% macro test() %}{{ varargs|join('|') }}{% endmacro %}\
 {{ test(1, 2, 3) }}\
 '''
 
 SIMPLECALL = '''\
-{% macro test %}[[{{ caller() }}]]{% endmacro %}\
+{% macro test() %}[[{{ caller() }}]]{% endmacro %}\
 {% call test() %}data{% endcall %}\
 '''
 
 COMPLEXCALL = '''\
-{% macro test %}[[{{ caller(data='data') }}]]{% endmacro %}\
+{% macro test() %}[[{{ caller(data='data') }}]]{% endmacro %}\
 {% call test() %}{{ data }}{% endcall %}\
 '''
 
@@ -63,17 +53,6 @@
     assert tmpl.render() == 'Hello Peter!'
 
 
-def test_kwargs_failure(env):
-    from jinja2.exceptions import TemplateRuntimeError
-    tmpl = env.from_string(KWARGSFAILURE)
-    try:
-        tmpl.render()
-    except TemplateRuntimeError, e:
-        pass
-    else:
-        raise AssertionError('kwargs failure test failed')
-
-
 def test_scoping(env):
     tmpl = env.from_string(SCOPING)
     assert tmpl.render() == 'foo|bar|'
@@ -84,11 +63,6 @@
     assert tmpl.render() == '||c|d|a||c|d|a|b|c|d|1|2|3|d'
 
 
-def test_parentheses(env):
-    tmpl = env.from_string(PARENTHESES)
-    assert tmpl.render() == '1|2'
-
-
 def test_varargs(env):
     tmpl = env.from_string(VARARGS)
     assert tmpl.render() == '1|2|3'
diff --git a/tests/test_syntax.py b/tests/test_syntax.py
index 4cce6a2..dc91990 100644
--- a/tests/test_syntax.py
+++ b/tests/test_syntax.py
@@ -36,10 +36,7 @@
     '{{ 1, 2 }}',
     '{% for foo, bar in seq %}...{% endfor %}',
     '{% for x in foo, bar %}...{% endfor %}',
-    '{% for x in foo, %}...{% endfor %}',
-    '{% for x in foo, recursive %}...{% endfor %}',
-    '{% for x in foo, bar recursive %}...{% endfor %}',
-    '{% for x, in foo, recursive %}...{% endfor %}'
+    '{% for x in foo, %}...{% endfor %}'
 ]
 TRAILINGCOMMA = '''{{ (1, 2,) }}|{{ [1, 2,] }}|{{ {1: 2,} }}'''