Metadata-Version: 1.1
Name: pypage
Version: 2.0.7
Summary:  Light-weight Python Templating Engine
Home-page: https://github.com/arjun-menon/pypage
Author: Arjun G. Menon
Author-email: contact@arjungmenon.com
License: Apache
Download-URL: https://github.com/arjun-menon/pypage/archive/v2.0.7.tar.gz
Description: pypage |build| |pypi| |docs|
        ============================
        
        pypage is a document template engine for Python programmers with a
        short learning curve.
        
        **Why use pypage?**
        
        -  Easy to pick up. Syntax similar to Python's.
        -  You need an eval-based template engine.
        
        pypage supports Python 3.x and 2.7, and has been `tested <https://travis-ci.org/arjun-menon/pypage>`_
        (using `test_cmd <https://github.com/arjun-menon/test_cmd>`_) on CPython and PyPy.
        
        **What does it look like?**
        
        .. code:: html
        
            <ul id="users">
              {% for user in users %}
                <li>
                  <a href="mailto: {{ html_ascii( user.email ) }}">{{ user.name }}</a>
                </li>
              {% endfor %}
            </ul>
        
        **Installation**
        
        You can `install <https://docs.python.org/3/installing/>`_ pypage easily with `pip <https://pip.pypa.io/en/stable/>`_:
        
        .. code::
        
            pip install pypage
        
        Try running ``pypage -h`` to see the command-line options available.
        
        .. contents:: **Table of Contents**
        
        
        Embedding Code
        --------------
        
        In order to embed code in a document, you wrap Python code with ``{{``
        and ``}}``. The ``{{ ... }}`` constructs are called **code tags**. There
        are two kinds of code tags: *inline* and *multiline*.
        
        Inline Code Tags
        ^^^^^^^^^^^^^^^^
        
        Inline code tags occur entirely on the same line, i.e. the closing
        ``}}`` appears on the same line as the opening ``{{``. Here is an
        example of an inline code tag:
        
        .. code:: python
        
            There are {{ 5 + 2 }} days in a week.
        
        The above, when processed by pypage, yields:
        
        ::
        
            There are 7 days in a week.
        
        The Python ``eval`` statement is used to execute the code in an inline
        code tag. The result of the expression evaluation is converted into a
        string (with ``str``) and the code tag is replaced with it.
        
        Multiline Code Tags
        ^^^^^^^^^^^^^^^^^^^
        
        Multiline code tags span multiple lines. The presence of one or more
        newline (``\n``) characters between the ``{{`` and ``}}`` distinguishes
        it from an inline code tag. Here's an example:
        
        .. code:: python
        
            {{
                x = 5
                y = 2
        
                write("There are", x + y, "days in a week.")
            }}
        
        The Python ``exec`` function is used to execute the code in a multiline
        code tag.
        
        Why have distinct inline code tags? It's easier to write ``{{x}}`` than
        to write ``{{ write(x) }}``. Many a time, all we need to do is inject
        the value of a variable at a specific location in the document.
        
        Execution Environment
        ^^^^^^^^^^^^^^^^^^^^^
        
        All code is executed in a shared common environment. I.e., the ``locals`` and
        ``globals`` passed into ``eval`` and ``exec`` is a single shared dictionary,
        for all code tags in the same file.
        
        As such, a variable instantiated in a code tag at the
        beginning of the document, will be available to all other code tags in
        the document. When pypage is invoked as library, an initial seed
        environment consisting of a Python dictionary mapping variable names to
        values, can be provided.
        
        The write function
        ''''''''''''''''''
        
        A ``write`` function similar to the Python 3's ``print`` function
        is accessible from both kinds of code tags. It writes text into
        the document that substitutes/replaces the code tag it's used in.
        
        .. code:: python
        
            write(*object, sep=' ', end='\n')
        
        Objects passed to it are stringified with ``str``, concatenated together
        with ``sep``, and terminated with ``end``. The outputs of multiple calls
        to ``write`` in a code tag are concatenated together, and the resulting
        final output is injected in place of the code tag.
        
        If ``write`` is called from an inline code tag, the result of evaluating
        the expression (a ``None``, since ``write`` will return a ``None``) is
        ignored, and the output of the ``write`` call is used instead.
        
        Block Tags
        ----------
        
        Block tags simplify certain tasks that would otherwise be cumbersome and
        ugly if done exclusively with code tags. One of the things it lets you
        do is wrap part of your page in an `if/else
        conditional <http://en.wikipedia.org/wiki/Conditional_(computer_programming)>`__,
        or a `for/while
        loop <http://en.wikipedia.org/wiki/Control_flow#Loops>`__.
        
        Here's an example of the ``for`` block tag:
        
        .. code:: python
        
            {% for i in range(10) %}
                The square of {{i}} is {{i*i}}.
            {% %}
        
        A block tag begins with ``{% tag_name ... %}`` and ends with ``{% %}``.
        Optionally, the end ``{% %}`` can be of the form ``{% endtag_name %}``
        (i.e. prepend the ``tag_name`` with ``end``), which in the above example
        would be ``{% endfor %}``).
        
        Conditional Blocks
        ^^^^^^^^^^^^^^^^^^
        
        It's best to explain this with an example:
        
        .. code:: python
        
            Hey,
            {{
              import random
              # Randomly pick a greeting
              greeting = random.randint(1,4)
            }}
            {% if greeting == 1 %}
              Hello
            {% elif greeting == 2 %}
              Bonjour
            {% elif greeting == 3 %}
              Hey
            {% else %}
              Hi
            {% %}
        
        When the above template is run, the resulting page will contain a
        randomly chosen greeting. As is evident, pypage syntax for if/elif/else
        conditions closely mirrors Python's. The terminal ``{% %}`` can be
        replaced with an ``{% endif %}`` with no change in meaning (as with any
        block tag).
        
        For Loops
        ^^^^^^^^^
        
        Let's start with a simple example:
        
        .. code:: python
        
            {% for vowel in ['a', 'e', 'i', 'o', 'u'] %}{{vowel}} {% %}
        
        This will print out the vowels with a space after every character.
        
        Now that's an ordinary for loop. pypage permits for loops that are more
        expressive than traditional Python for loops, by leveraging Python's
        *generator expressions*.
        
        Here's an example of something that would be impossible to do in Python
        (with a regular for loop):
        
        .. code:: python
        
            {% for x in [1,2,3] for y in ['a','b','c'] %}
                {{x}} ~ {{y}}
            {%%}
        
        The above loop would result in:
        
        ::
        
            1 ~ a
            1 ~ b
            1 ~ c
            2 ~ a
            2 ~ b
            2 ~ c
            3 ~ a
            3 ~ b
            3 ~ c
        
        *Internally*, pypage morphs the expression
        ``for x in [1,2,3] for y in ['a','b','c']`` into the generator
        expression ``(x, y) for x in [1,2,3] for y in ['a','b','c']``. It
        exposes the the loop variables ``x`` and ``y`` by injecting them into
        your namespace.
        
        *Note:* Injected loop variables replace variables with the same name for
        the duration of the loop. After the loop, the old variables with the
        identical names are restored (pypage backs them up).
        
        While Loops
        ^^^^^^^^^^^
        
        A while loops looks like ``{{% while condition %}} ... {{% %}``, where
        ``condition`` can be any Python expression. Here's an example:
        
        .. code:: python
        
            {{
                i = 10
                j = 20
            }}
            Numbers from {{i}} to {{j}}:
            {% while i <= j %}
            {{
                write(str(i))
                i += 1
            }}
            {% %}
        
        This would simply list the numbers from 10 to 20.
        
        dofirst Loops
        '''''''''''''
        
        .. code:: python
        
            {% while dofirst False %}
            That's all, folks!
            {%%}
        
        Adding a ``dofirst`` right after the ``while`` and before the expression
        ensures that the loop is run *at least once*, before the condition is
        evaluated.
        
        Long Loops
        ''''''''''
        
        If a loop runs *for more than 2 seconds*, pypage stops executing it, and
        writes an error message to ``stdout`` saying that the loop had been
        terminated. As pypage is mostly intended to be used as a templatig
        language, loops generally shouldn't be running for longer than two
        seconds, and this timeout was added to make it easier to catch accidental
        infinite loops. If you actually need a loop to run for longer than 2
        seoncds, you can add the keyword ``slow`` right after the condition expression
        (``{{% while condition slow %}}``), and that would suppress this 2-second timeout.
        
        Capture Blocks
        ^^^^^^^^^^^^^^
        
        You can capture the output of part of your page using the ``capture``
        tag:
        
        .. code:: python
        
            {% capture x %}
              hello {{"bob"}}
            {% %}
        
        The above tag will not yield any output, but rather a new variable ``x``
        will be created that captures the output of everything enclosed by it
        (which in this case is ``"hello bob"``).
        
        Finer Details
        -------------
        
        Inheritance (with inject and exists)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        
        The approach taken by pypage toward template inheritance is quite distinct from that of other
        templating engines (`like Jinja's <http://jinja.pocoo.org/docs/2.10/templates/#template-inheritance>`_).
        It's a lot simpler. You call a pypage-provided function ``inject`` with the path of a *pypage template* you want
        to inject (i.e. "*extend*" in Jinja parlance), and pypage will process that template under the current scope (with all
        previously defined variables being available to the injected template), and the ``inject`` function will return its output.
        
        A base template could look like this:
        
        .. code:: html
        
            <html>
            <head>
                <title>
                    {% if exists('title') %}
                    {{ title }}
                    {% else %}
                    No title
                    {% %}
                </title>
            </head>
            <body>
            {{ body }}
            </body>
            </html>
        
        A derived templates only needs to define ``body`` and optionally ``title``, to "extend" the template above.
        
        .. code::
        
            {% capture body %}
            The HTML body content would go in here.
            {% %}
            {{ inject('...path to the base template...') }}
        
        We didn't specify a ``title`` above, but if we wanted to, we'd just need to make sure it was defined before ``inject``
        was called. The base template checks whether a ``title`` variable exists by calling the function ``exists``. As is obvious,
        the ``exists`` function simply takes a variable name as a string, and returns a boolean indicating whether the variable
        exists in the scope.
        
        This approach to inheritance is explicit and easy-to-grasp. Rather than have complex inheritance rules, with a default
        block definition that is optionally overridden by a derived template, we make things more explicit by using conditionals
        for cases where we want to provide a default/fallback definition. We error out if a definition is expected to be provided,
        and is not present. The output of the "dervied" template is clear and obvious, with this approach.
        
        The include function
        ''''''''''''''''''''
        
        If you want to include (as in, substitute) a file directly without processing it with pypage, you can use the
        ``include`` function. It functions like the ``inject`` function, taking the path to a file as argument, and
        returning the contents of the file unprocessed.
        
        Comments
        ^^^^^^^^
        
        Comment Tags
        ''''''''''''
        
        Anything bounded by ``{#`` and ``#}`` will be omitted from the output.
        For example:
        
        .. code:: html
        
            <p>
              Lorem ipsum dolor sit amet
              {#
                <ul>
                    Non sequitur
                </ul>
              #}
              consectetur adipisicing elit
            </p>
        
        Comment Blocks
        ''''''''''''''
        
        You can also easily comment an existing block, by simply placing the word ``comment`` in front of it:
        
        .. code:: html
        
            <p>
              Lorem ipsum dolor sit amet
                {% comment for i in range(10) %}
                    N = {{i}}
                {% %}
              consectetur adipisicing elit
            </p>
        
        The ``comment`` keyword before the ``for`` above results in the entire block
        being commented out and omitted from the output.
        
        Whitespace & Indentation
        ^^^^^^^^^^^^^^^^^^^^^^^^
        
        Whitespace Removal
        ''''''''''''''''''
        
        If a block tag is on a line by itself, surrounded only by whitespace,
        then that whitespace is automatically excluded from the output. This
        allows you indent your block tags without worrying about excess
        whitespace in the generated document.
        
        Automatic Indentation
        '''''''''''''''''''''
        
        pypage smartly handles indentation for you. In a multi-line code tag, if
        you consistently indent your Python code with a specific amount of
        whitespace, that indentation will be stripped off before executing the
        code block (as Python is indentation-sensitive), and the resulting
        output of that code block will be re-indented with same whitespace that
        the initial code block was.
        
        The whitespace preceding the second line of code determines the
        peripheral indentation for the entiee block. All subsequent lines (after
        second) must begin with exact same whitespace that preceded the second
        line, or be an empty line.
        
        For example:
        
        .. code:: html
        
            <p>
              Lorem ipsum dolor sit amet
                <ul>
                  {{
                    def foo():
                      write("Hello!")
                    foo()
                  }}
                </ul>
              consectetur adipisicing elit
            </p>
        
        would produce the following output:
        
        .. code:: html
        
            <p>
              Lorem ipsum dolor sit amet
                <ul>
                    Hello!
                </ul>
              consectetur adipisicing elit
            </p>
        
        Note that the ``Hello!`` was indented with same whitespace that the code
        in the code block was.
        
        pypage automatically intends the output of a multi-line tag to match the
        indentation level of the code tag. The number of whitespace characters
        at the beginning of the second line of the code block determines the
        indentation level for the whole block. All lines of code following the
        second line must at least have the same level of indentation as the
        second line (or else, a PypageSyntaxError exception will be thrown).
        
        License
        ^^^^^^^
        
        `Apache License Version
        2.0 <https://www.apache.org/licenses/LICENSE-2.0>`__
        
        .. |build| image:: https://travis-ci.org/arjun-menon/pypage.svg?branch=master
           :target: https://travis-ci.org/arjun-menon/pypage
        .. |pypi| image:: https://badge.fury.io/py/pypage.svg
           :target: https://pypi.python.org/pypi/pypage
        .. |docs| image:: https://readthedocs.org/projects/pypage/badge/?version=latest&style=flat
           :target: https://pypage.readthedocs.io/en/latest/
        
Keywords: templating enigne text processing static generator
Platform: UNKNOWN
Classifier: Topic :: Text Processing
Classifier: Topic :: Internet :: WWW/HTTP
Classifier: Topic :: Text Processing :: Markup :: HTML
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Intended Audience :: Developers
Classifier: Environment :: Console
Classifier: Environment :: Web Environment
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.2
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
