Llabel demo class for constructing class objects with different constructors and exporting them in different ways

Llabel.py

#!/usr/bin/env python
# -*- coding: utf8 -*-


class Llabel(object):

    """
    Lfunction Label
    ---------------

    Description of D, deltas, ...
    """

    def __init__(self, D, deltas, N, chi, mu):
        """
        Main Constructor
        """
        # TODO: add validation for each argument
        self.D = D
        self.deltas = deltas
        self.N = N
        self.chi = chi
        self.mu = mu

    @classmethod
    def from_string(klass, s):
        """
        parses the string @s and returns the Llabel object
        """
        # this is only a DEMO!!!
        D = s[:3]
        deltas = map(float, s[3:10].split("_"))
        N = 1
        chi = 2
        mu = [1.1, 1.5, 2]
        # and more
        return klass(D, deltas, N, chi, mu)

    @classmethod
    def from_url(klass, u):
        """
        """
        ul = u.split("/")
        raise Exception("NYI")

    @classmethod
    def from_dblabel(klass, l):
        """
        uses l to construct the class
        """
        D, deltas, N, chi, mu = l
        return klass(D, deltas, N, chi, mu)

    def to_string(self):
        """
        converts the internal state to the string representation
        """
        deltas = '_'.join(map(str, self.deltas))
        mu = '_'.join(map(str, self.mu))
        return '__'.join(map(str, [self.D, deltas, self.N, self.chi, mu]))

    def to_url(self):
        """
        ...
        """
        deltas = '_'.join(map(str, self.deltas))
        mu = '_'.join(map(str, self.mu))
        return '/'.join(map(str, [self.D, deltas, self.N, self.chi, mu]))

    def to_dblabel(self):
        return [self.D, self.deltas, self.N, self.chi, self.mu]

    def __str__(self):
        """
        canonical string
        """
        return 'Llabel: %s' % self.to_url()


if __name__ == '__main__':
    print "creating one"
    l1 = Llabel(22, [1.5, -1], 1, 2, [1.1, 2.123, -1, 5])
    print 'as string:', l1.to_string()
    print 'as db_label:', l1.to_dblabel()
    print 'and as url:', l1.to_url()

    print
    print "from a label to the Llabel object"
    l1_db = l1.to_dblabel()

    print l1_db
    print type(l1_db)
    print

    l_new = Llabel.from_dblabel(l1_db)
    print l_new  # calls __str__
    print type(l_new)
    print

    print "the old D is = %s" % l1.D
    print "the new D is = %s" % l_new.D
    # are they equal -> that's a test ;-)