Example: using werkzeug cache with flask.render_template_string

python console

>>> # flask shell
>>> from short_templates import *
>>> NameTemplate.render(site_name='Flask', name='John')
u'Thank you for visiting Flask. I am John.'
>>> NameDateTemplate.render(site_name='Flask', name='John')
u'Thank you for visiting Flask. I am John. Today is 2017-06-29.'

short_templates.py

# app/short_templates.py
import json
from datetime import date

from flask import render_template_string
from werkzeug.contrib.cache import SimpleCache  # or Redis or Memcache

cache = SimpleCache()

class CachedTemplateString(object):
    """Subclass me and make the template my docstring. I will cache the results."""
    _cache = cache

    @classmethod
    def render(cls, **kwargs):
        params = cls.defaults()
        params.update(kwargs)
        key = cls.make_key(**params)
        val = cls._cache.get(key)
        if val is None:
            val = render_template_string(cls.__doc__, **params)
            cls._cache.set(key, val)
        return val

    @classmethod
    def make_key(cls, **kwargs):
        return json.dumps((cls.__name__, kwargs))

    @classmethod
    def defaults(cls):
        return {}

class NameTemplate(CachedTemplateString):
    """Thank you for visiting {{site_name}}. I am {{name}}."""


class NameDateTemplate(CachedTemplateString):
    __doc__ = NameTemplate.__doc__ + " Today is {{today}}."

    @classmethod
    def defaults(cls):
        return {'today': date.today()}

    @classmethod
    def make_key(cls, today=None, **kwargs):
        return super(NameDateTemplate, cls).make_key(today=str(today),
                                                     **kwargs)