Cacher

The Cacher classes’ aim is to save some data to files for long-term usage. One could see them as very simplistic databases.

Model Usage

As for the logger, if a cacher was initialized by the settings while running colifrapy, “cache” will be a reserved attribute of any of your models.

It is possible to register more than one cache instance with the Settings class. To achieve this, see cache settings.

from colifrapy import Model

class MyModel(Model):
    def test(self):

        # We assume that a line cache file containing
        # the string "Hello" was loaded
        print self.cache.get()
        >>> 'Hello'

Standalone Usage

You can also use the Cacher classes as standalones rather than within colifrapy’s architecture.

from colifrapy import LineCacher, YAMLCacher

line_cache = LineCacher(options)
yaml_cache = YAMLCacher(options)

Modes

Line Cacher

The Line Cacher consists in a strict one-liner file and is aimed at storing really simple data.

Example of cache file content

1245

YAML Cacher

The YAML Cacher is designed to store more complex states of data and organized in a key-value fashion. The readability of the YAML file format makes the cache file easy to manually modify if needed. This is also possible to create deep nested data structures that will be accessible by paths.

Example of cache file content

number_of_tries: 14
countries:
    albania: True
    united_kingdom: "Hello"

Options

Here are the possible options you may pass to the Cacher classes constructors :

• directory

  (string)
  directory where you want to store your cache
  default: “cache/”

• filename

  (string)
  name of the cache file
  default: “cache.txt” or “cache.yml”

• auto_write

  (boolean)
  whether you want your cache to be automatically written when changed or not. If set to False, you’ll have to write the invoke the cache writing manually.
  default: False

Methods

Line Cacher

from colifrapy import Model

class MyModel(Model):
    def test(self):

    # Setting cache
    self.cache.set('Hello')

    # Getting cache
    print self.cache.get()
    >>> 'Hello'

    # Writing to cache
    # N.B. : Useless if auto_write is set to True
    self.cache.write()

    # Deleting cache
    self.cache.delete()


    # Reading and writing filters
    # Example of a single date cached
    date_format = "%Y/%m/%d %H:%M:%S"
    self.cache.setReadingFilter(lambda x: datetime.strptime(x, date_format))
    self.cache.setWritingFilter(lambda x: x.strftime(date_format))

YAML Cacher

from colifrapy import Model

class MyModel(Model):
    def test(self):

        # Setting cache
        self.cache.set("one", "red")
        self.cache.set("two:deep", "blue")

        # Getting cache
        print self.cache.get("one")
        >>> "red"

        print self.cache.get("two")
        >>> {"deep" : "blue"}

        print self.cache.get("two:deep")
        >>> "blue"

        print self.cache
        >>> {"one" : "red", "two" : {"deep" : "blue"}}

        # Unset path
        self.cache.unset("two")
        print self.cache
        >>> {"one" : "red"}

        # Overwriting cache
        self.cache.overwrite({'other' : 'structure'})
        print self.cache
        >>> {'other' : 'structure'}


        # Writing to cache
        # N.B. : Useless if auto_write is set to True
        self.cache.write()

        # Deleting cache
        self.cache.delete()