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NText

Simple templating tool.

Example:

#!/usr/bin/env python

from ntext import Templates, trim

# Step 1: define templates

templates = Templates(
    menu = '<<day>_menu>',
    Monday_menu = '<opened>',
    Tuesday_menu = '<opened>',
    Wednesday_menu = '<opened>',
    Thursday_menu = '<closed, cause=its almost weekend>',
    Friday_menu = '<closed, cause=its almost weekend>',
    Saturday_menu = '<closed, cause=its weekend>',
    Sunday_menu = '<closed, cause=<chef> is sick>',
    opened = trim(
        """
        Welcome!
        Menu:
          <<day>_items>
        Today's special:
          <<chef>s_special>
        """),
    closed = "We are closed because <cause>!",
    Monday_items = trim(
        """
        Sandwich
        Soup
        """),
    Tuesday_items = trim(
        """
        Beef
        Chicken Curry
        """),
    Wednesday_items = 'Scrambled Eggs',
    Marios_special = 'Snails!',
    Luigis_special = 'Pizza!'
)

# Step 2: generate text from a template

print templates.expand('<menu, day=Monday, chef=Mario>')

prints:

Welcome!
Menu:
  Sandwich
  Soup
Today's special:
  Snails!

while

print templates.expand('<menu, day=Friday, chef=Mario>')

would print:

We are closed because Mario is sick!

In Step 1 we are binding template names to templates. Templates class is a subclass of dict - instances can be constructed and manipulated in the same ways.

A template body can contain plain text and references to other templates. Templates are referenced by their names surrounded by angle brackets.

The Templates class adds one public method to the dict class:

.expand(text, **kwargs)

where text is a template and keyword arguments can be used to define additional templates. A fully expanded template is returned.

Name scope

In Step 1 we have defined global names; these names can be used anywhere.

Note that some templates refer to day and chef but Step 1 does not define what day and chef are.

This is done in step 2; referring to the menu as <menu, day=Monday, chef=Mario> defines day to be "Monday" and chef to be "Mario". The scope of these two names is:

  • inside of the <menu,... name string
  • inside of the menu template body
  • further down the call stack

Trying to expand <menu> without arguments would throw UndefinedTemplateError.

Alternative call (does the same): templates.expand('<menu>', day='Monday', chef='Mario')

Indirect referencing

Templates are referenced by names (e.g. <closed> is a reference to the "We are closed because <cause>!" template) but template names can be templated themselves. This indirect referencing is used for flow control, e.g. <<chef>s_special> is either a reference to "Snails!" or a reference to "Pizza!", depending on the chef.