allow extensions to be append to template engine.

.azure-pipelines-steps-macos.yml

@@ -3,6 +3,7 @@ steps:
   displayName: 'Use Python 3.x'
 - script: |
     python -m pip install --upgrade pip setuptools wheel
+    test ! -f rnd_requirements.txt || pip install -r rnd_requirements.txt
     pip install -r requirements.txt
     pip install -r tests/requirements.txt
   displayName: 'Setup dependencies'

.azure-pipelines-steps.yml

@@ -3,6 +3,7 @@ steps:
   displayName: 'Use Python 3.x'
 - script: |
     python -m pip install --upgrade pip setuptools wheel
+    if exist rnd_requirements.txt pip install -r rnd_requirements.txt
     pip install -r requirements.txt
     pip install -r tests\requirements.txt
   displayName: 'Setup dependencies'

.moban.cd/changelog.yml

@@ -1,6 +1,13 @@
 name: moban
 organisation: moremoban
 releases:
+- changes:
+  - action: Updated
+    details:
+    - "`#90`: allow adding extra jinja2 extensions. `jinja2.ext.do`, `jinja2.ext.loopcontrols` are included by default. what's more, any other template enigne are eligible for extension additions."
+    - "`#158`: Empty file base_engine.py is finally removed"
+  date: 12-1-2019
+  version: 0.3.9
 - changes:
   - action: Updated
     details:

.moban.cd/moban.yml

@@ -3,14 +3,14 @@ organisation: moremoban
 author: C. W.
 contact: wangc_2011@hotmail.com
 license: MIT
-version: 0.3.8
-current_version: 0.3.8
+version: 0.3.9
+current_version: 0.3.9
 release: 0.3.8
 branch: master
 command_line_interface: "moban"
 entry_point: "moban.main:main"
 company: Onni Software Ltd.
-copyright_year: 2017-2018
+copyright_year: 2017-2019
 keywords:
   - jinja2
   - moban

.travis.yml

@@ -7,6 +7,7 @@ python:
   - 3.7-dev
   - 3.6
   - 3.5
+  - 3.4
   - 2.7
 before_install:
   - if [[ $TRAVIS_PYTHON_VERSION == "2.6" ]]; then pip install flake8==2.6.2; fi

CHANGELOG.rst

@@ -1,6 +1,19 @@
 Change log
 ================================================================================
 
+0.3.9 - 12-1-2019
+--------------------------------------------------------------------------------
+
+Updated
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. `#90 <https://github.com/moremoban/moban/issues/90>`_: allow adding extra
+   jinja2 extensions. `jinja2.ext.do`, `jinja2.ext.loopcontrols` are included by
+   default. what's more, any other template enigne are eligible for extension
+   additions.
+#. `#158 <https://github.com/moremoban/moban/issues/158>`_: Empty file
+   base_engine.py is finally removed
+
 0.3.8 - 12-1-2019
 --------------------------------------------------------------------------------
 

docs/conf.py

@@ -24,13 +24,13 @@
 # -- Project information -----------------------------------------------------
 
 project = u'moban'
-copyright = u'2017-2018 Onni Software Ltd.'
+copyright = u'2017-2019 Onni Software Ltd.'
 author = u'C. W.'
 
 # The short X.Y version
 version = u'0.3.8'
 # The full version, including alpha/beta/rc tags
-release = u'0.3.8'
+release = u'0.3.9'
 
 
 # -- General configuration ---------------------------------------------------

docs/level-12-use-template-engine-extensions/.moban.yml

@@ -0,0 +1,6 @@
+targets:
+  - a.output: a.template
+  - b.output: b.template
+extensions:
+  jinja2:
+    - jinja2.ext.with_

docs/level-12-use-template-engine-extensions/README.rst

@@ -0,0 +1,36 @@
+Level 12: use template engine extensions
+================================================================================
+
+jinja2 comes with a lot of extensions. In order not to be the blocker in the
+middle, **extensions** is allowed in moban file to initialize jinja2 engine
+with desired extensions. Two extensions, expression-statement and loop-controls
+are enabled by default.
+
+The extensions syntax is::
+
+   extensions:
+     template_type:
+       - template.engine.specific.extension
+
+For example::
+
+   extensions:
+     jinja2:
+       - jinja2.ext.i18n
+
+Please also note that the following extensions are included by default:
+`jinja2.ext.do`, `jinja2.ext.loopcontrols`
+
+
+Evaluation
+--------------------------------------------------------------------------------
+Please go to `docs/level-12-use-template-engine-extensions` directory.
+
+If you notice the file `a.template`, we are using a for loop control. This is
+because moban comes with two default extensions loop-controls and
+expression-statement.
+
+Now, let us try to use the extension `with`. To do that, we have to enable the
+extension in the `.moban.yml` file following the above syntax. Now, the
+extension can be used in the jinja2 templates. One such example is shown in the
+`b.template` file.

docs/level-12-use-template-engine-extensions/a.template

@@ -0,0 +1,3 @@
+{% for _ in range(1,5) %}
+{{ hello }}
+{% endfor %}

docs/level-12-use-template-engine-extensions/b.template

@@ -0,0 +1,9 @@
+{% with %}
+    {% set foo = 142 %}
+{{ foo }}
+    {% with %}
+        {% set foo = 42 %}
+{{ foo }}
+    {% endwith %}
+{{ foo }}
+{% endwith %}

docs/level-12-use-template-engine-extensions/data.yml

@@ -0,0 +1 @@
+hello: world

moban/_version.py

@@ -1,2 +1,2 @@
-__version__ = "0.3.8"
+__version__ = "0.3.9"
 __author__ = "C. W."

moban/constants.py

@@ -23,15 +23,13 @@
 LABEL_TEMPLATE = "template"
 POSITIONAL_LABEL_TEMPLATE = "template_in_string"
 LABEL_TMPL_DIRS = "template_dir"
+LABEL_EXIT_CODE = "exit-code"
 LABEL_OUTPUT = "output"
 LABEL_TEMPLATE_TYPE = "template_type"
-LABEL_TARGETS = "targets"
-LABEL_COPY = "copy"
 LABEL_OVERRIDES = "overrides"
 LABEL_MOBANFILE = "mobanfile"
 LABEL_FORCE = "force"
-LABEL_REQUIRES = "requires"
-LABEL_EXIT_CODE = "exit-code"
+
 
 DEFAULT_CONFIGURATION_DIRNAME = ".moban.cd"
 DEFAULT_TEMPLATE_DIRNAME = ".moban.td"
@@ -52,6 +50,11 @@
 DEFAULT_MOBAN_VERSION = "1.0"
 MOBAN_DIR_NAME_UNDER_USER_HOME = ".moban"
 MOBAN_REPOS_DIR_NAME = "repos"
+# moban file configuration
+LABEL_REQUIRES = "requires"
+LABEL_TARGETS = "targets"
+LABEL_COPY = "copy"
+LABEL_EXTENSIONS = "extensions"
 
 # error messages
 ERROR_DATA_FILE_NOT_FOUND = "Both %s and %s does not exist"

moban/jinja2/engine.py

@@ -12,10 +12,7 @@
     "moban.jinja2.filters.text",
     "moban.jinja2.tests.files",
 ]
-JINJA2_THIRD_PARTY_EXTENSIONS = [
-    'jinja2.ext.do',
-    'jinja2.ext.loopcontrols',
-]
+JINJA2_THIRD_PARTY_EXTENSIONS = ["jinja2.ext.do", "jinja2.ext.loopcontrols"]
 
 
 class PluginMixin:
@@ -54,7 +51,7 @@ def __init__(self):
     constants.TEMPLATE_ENGINE_EXTENSION, tags=["jinja2", "jinja", "jj2", "j2"]
 )
 class Engine(object):
-    def __init__(self, template_dirs):
+    def __init__(self, template_dirs, extensions=None):
         """
         Contruct a jinja2 template engine
 
@@ -65,13 +62,19 @@ def __init__(self, template_dirs):
         load_jinja2_extensions()
         self.template_dirs = template_dirs
         template_loader = FileSystemLoader(template_dirs)
-        self.jj2_environment = Environment(
+        env_params = dict(
             loader=template_loader,
             keep_trailing_newline=True,
             trim_blocks=True,
             lstrip_blocks=True,
-            extensions=JINJA2_THIRD_PARTY_EXTENSIONS,
+            extensions=[
+                extension for extension in JINJA2_THIRD_PARTY_EXTENSIONS
+            ],  # get a copy of this global variable
         )
+        if is_extension_list_valid(extensions):
+            # because it is modified here
+            env_params["extensions"] += extensions
+        self.jj2_environment = Environment(**env_params)
         for filter_name, filter_function in FILTERS.get_all():
             self.jj2_environment.filters[filter_name] = filter_function
 
@@ -125,3 +128,11 @@ def apply_template(self, template, data, output):
 
 def load_jinja2_extensions():
     scan_plugins_regex(JINJA2_LIBRARIES, "moban", None, JINJA2_EXENSIONS)
+
+
+def is_extension_list_valid(extensions):
+    return (
+        extensions is not None
+        and isinstance(extensions, list)
+        and len(extensions) > 0
+    )

moban/mobanfile.py

@@ -68,6 +68,10 @@ def handle_moban_file_v1(moban_file_configurations, command_line_options):
     if requires:
         handle_requires(requires)
 
+    extensions = moban_file_configurations.get(constants.LABEL_EXTENSIONS)
+    if extensions:
+        plugins.ENGINES.register_extensions(extensions)
+
     if targets:
         # If template specified via CLI flag `-t:
         # 1. Only update the specified template

moban/plugins.py

@@ -21,15 +21,17 @@ def resource_path_of(self, library_name):
 
 
 class BaseEngine(object):
-    def __init__(self, template_dirs, context_dirs, engine_cls):
+    def __init__(
+        self, template_dirs, context_dirs, engine_cls, engine_extensions=None
+    ):
         # pypi-moban-pkg cannot be found if removed
         make_sure_all_pkg_are_loaded()
         template_dirs = list(expand_template_directories(template_dirs))
         verify_the_existence_of_directories(template_dirs)
         context_dirs = expand_template_directory(context_dirs)
         self.context = Context(context_dirs)
         self.template_dirs = template_dirs
-        self.engine = engine_cls(self.template_dirs)
+        self.engine = engine_cls(self.template_dirs, engine_extensions)
         self.engine_cls = engine_cls
         self.templated_count = 0
         self.file_count = 0
@@ -143,10 +145,17 @@ def __init__(self):
         super(EngineFactory, self).__init__(
             constants.TEMPLATE_ENGINE_EXTENSION
         )
+        self.extensions = {}
+
+    def register_extensions(self, extensions):
+        self.extensions.update(extensions)
 
     def get_engine(self, template_type, template_dirs, context_dirs):
         engine_cls = self.load_me_now(template_type)
-        return BaseEngine(template_dirs, context_dirs, engine_cls)
+        engine_extensions = self.extensions.get(template_type)
+        return BaseEngine(
+            template_dirs, context_dirs, engine_cls, engine_extensions
+        )
 
     def all_types(self):
         return list(self.registry.keys())

rnd_requirements.txt

@@ -0,0 +1 @@
+https://github.com/moremoban/moban-handlebars/archive/dev.zip

setup.py

@@ -13,7 +13,7 @@
 
 NAME = 'moban'
 AUTHOR = 'C. W.'
-VERSION = '0.3.8'
+VERSION = '0.3.9'
 EMAIL = 'wangc_2011@hotmail.com'
 LICENSE = 'MIT'
 ENTRY_POINTS = {

tests/test_docs.py

@@ -107,6 +107,23 @@ def test_level_11(self):
         folder = "level-11-use-handlebars"
         self._raw_moban(["moban"], folder, expected, "a.output")
 
+    def test_level_12_a(self):
+        expected_a = """world
+world
+world
+world
+"""
+        folder = "level-12-use-template-engine-extensions"
+        self._raw_moban(["moban"], folder, expected_a, "a.output")
+
+    def test_level_12_b(self):
+        expected_b = """142
+42
+142
+"""
+        folder = "level-12-use-template-engine-extensions"
+        self._raw_moban(["moban"], folder, expected_b, "b.output")
+
     def test_misc_1(self):
         expected = "test file\n"