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Code testing, patterns, profiles and optimisation. example from a Well House Consultants training course
More on Code testing, patterns, profiles and optimisation. [link]

This example is described in the following article(s):
   • A demonstration of how many Python facilities work together - [link]
   • Passing optional and named parameters to python methods - [link]

Source code: travel.py Module: Y212
#!/usr/bin/env python

# inheritance, factory, decorator, comparators, static methods
# import, exceptions, stderr, sys, object state caching

import sys

# An example from some more advanced object training ...

covercount = {}

def coverage(why):

        # define how to wrap the function call
        myname = why.func_name

        def wrapped(*args, **kwargs):

                # Do the original stuff (of course?)
                finalanswer = why(*args, **kwargs)

                # Extra bits to be performed ...
                sofar = covercount.get(myname,0)
                covercount[myname] = sofar + 1

                return finalanswer

        # pass back the wrapped function
        # and pass back the wrapped docstring too
        wrapped.__doc__ = why.__doc__
        return wrapped

def coverage_report():
        print "\nHow many times each method was called:"
        for func in covercount.keys():
                print covercount[func],func

class travel(object):
        def __init__(self,defstring):
                type, self.leaves, self.destiny, \
                self.carpacity, self.duration = defstring.split('\t')
                self.cars = 1
                self.cached = False
                self.regulator = "Maritime agency"

        def getdest(self):
                return self.destiny
        getdest = coverage(getdest)

        def getcars(self):
                return int(self.cars)

        def getadmins(self):
                return self.getpeeps() * int(self.duration)

        def more_opportunities(this,that):
                val = cmp(this.getadmins(), that.getadmins())
                if (val > 0): return this
                return that

        def most_opportunities(possibilities):
                        so_far = possibilities[0]
                for maybe in range(1,len(possibilities)):
                        so_far = so_far.more_opportunities(possibilities[maybe])
                return so_far

        def factory(line):
                have = None
                if line.startswith("train\t"):
                        have =train(line)
                elif line.startswith("bus\t"):
                        have = bus(line)
                elif line.startswith("floating bridge\t"):
                        have = ferry(line)
                if not have:
                        # exits function on "raise", no value returned
                        # raise creates an exception object
                        raise TypeError, "Not a valid travel mode"
                return have

        def getpeeps(self):
                if not self.cached:
                        self.peeps = int(self.carpacity) * int(self.cars)
                        self.cached = True
                return self.peeps

        def __str__(self):
                itsa = self.__class__.__name__
                passes = self.getpeeps()
                return "A " + "%-8s" % itsa + " with space for " + \
                        "%4d" % passes

        # set up an attribute called "people".
        # use the getpeeps method to read, and None to write
        people = property(getpeeps,None)

class train (travel):

        def __init__(self,defstring):
                type, self.leaves, self.destiny, self.cars, \
                self.carpacity, self.duration = defstring.split('\t')
                self.cached = False
                self.regulator = "ORR"

class roadie (travel):

class bus (roadie):

        def __init__(self,defstring):
                # travel.__init__(self, defstring)
                # Above is deprecated - use the following:
                self.regulator = "DfT"

        def getpeeps(self):
                if not self.cached:
                        self.peeps = int(self.carpacity) - 1
                        self.cached = True
                return self.peeps

class ferry(travel):

# ---------------------------------------------------------

if __name__ == "__main__":
        params = sys.argv
        if len(params) < 2:
                fh = sys.stdin
                        fh = open(sys.argv[1])
                except IOError, e:
                        sys.stderr.write("Error 1543: Can't open "+sys.argv[1]+" for read: ")
                        sys.stderr.write(e.strerror + "\n")
                        # Do not recussitate ;-)
                except StandardError, e:
                        sys.stderr.write("Error 1544: Dallas, we have an unusual problem\n")
                        sys.stderr.write("And it's a "+ e.__class__.__name__ + "\n")
        options = []
        for line in fh:

        summery = "\n"

        for option in options:
                if option.getpeeps() < 50: continue

                # strong suggestion - hide the formatting in the class

                print "%2d" % (option.getcars()), \
                        "%-15s" % option.getdest(), \
                        "%3d" % option.getpeeps()
                print "%2d - %15s - %10s - %3d - %3d" % (option.getcars(), \
                        option.getdest(), \
                        option.regulator, \
                        option.people, \

                summery += str(option) + "\n"
                # print option

        print summery

# Comparators


                first = options[3]
                second = options[5]

                print first
                print second

                print first.getadmins()
                print second.getadmins()

                sellon = first.more_opportunities(second)
                print sellon

                sys.stderr.write("Error 5544: you are short of data for comparators\n")

                sellon = travel.most_opportunities(options)
                print sellon
                sys.stderr.write('Error 5432: not even enough data for "most" test!!\n')

# Look at use of code


""" --------------------------------------------------------------

Sample data file:

train 07:17 Swindon 2 72 25
train 06:40 Southampton 2 71 89
train 19:11 Southampton 1 71 97
train 19:47 Cheltenham Spa 3 75 65
floating bridge 22:30 Hoek van Holland 1200 480
bus 07:24 Chippenham 62 24
bus 08:04 Bath 41 37
bus 08:07 Bath 61 35
floating bridge 09:20 Amsterdam 400 5
elephant 10:40 Atworth 5 45


Runs like this:

munchkin:ps grahamellis$ ./travel.py journey.txt
 2 Swindon 144
 2 - Swindon - ORR - 144 - 144
 2 Southampton 142
 2 - Southampton - ORR - 142 - 142
 1 Southampton 71
 1 - Southampton - ORR - 71 - 71
 3 Cheltenham Spa 225
 3 - Cheltenham Spa - ORR - 225 - 225
 1 Hoek van Holland 1200
 1 - Hoek van Holland - Maritime agency - 1200 - 1200
 1 Chippenham 61
 1 - Chippenham - DfT - 61 - 61
 1 Bath 60
 1 - Bath - DfT - 60 - 60
 1 Amsterdam 400
 1 - Amsterdam - Maritime agency - 400 - 400

A train with space for 144
A train with space for 142
A train with space for 71
A train with space for 225
A ferry with space for 1200
A bus with space for 61
A bus with space for 60
A ferry with space for 400

A train with space for 225
A bus with space for 61
A train with space for 225
A ferry with space for 1200

How many times each method was called:
12 __str__
9 factory
65 getpeeps
1 most_opportunities
9 more_opportunities
16 getcars
20 getadmins
12 __init__
16 getdest
munchkin:ps grahamellis$

----------- Another sample --------------

munchkin:ps grahamellis$ ./travel.py

Error 5544: you are short of data for comparators
Error 5432: not even enough data for "most" test!!

How many times each method was called:
munchkin:ps grahamellis$


Learn about this subject
This module and example are covered on the following public courses:
 * Learning to program in Python
 * Python Programming
Also available on on site courses for larger groups

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Other Examples
This example comes from our "Code testing, patterns, profiles and optimisation." training module. You'll find a description of the topic and some other closely related examples on the "Code testing, patterns, profiles and optimisation." module index page.

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