On 09/08/2017 03:06 AM, Peter Otten wrote:
leam hall wrote:
On Thu, Sep 7, 2017 at 8:16 AM, Steve D'Aprano
<steve+pyt...@pearwood.info> wrote:
On Thu, 7 Sep 2017 07:20 pm, Leam Hall wrote:
OOP newbie on Python 2.6.
Python 2.6 is ancient, and is missing many nice features. You should
consider
using the latest version, 3.6.
I've wrestled with that discussion for a while and Python 3 loses every
time. There's literally no good reason for me to move to Python 3 earlier
than mid-2020's. Please accept the fact that there are hundreds of
thousands of servers, if not millions, running Python 2.x. Whether or not
Python 3 has any neat cool stuff is irrelevant to those of us seeking to
use Python to get today's work done.
I create instances of Character class with an attribute dict of
'skills'. The 'skills' dict has the name of a skill as the key and an
int as a value. The code adds or modifies skills before outputting the
Character.
Is it better design to have a Character.method that takes a 'skill' key
and optional value or to have a general function that takes an
instance, a dict, a key, and an optional value?
I'm afraid your example is too generic for me to give an opinion. Do you
literally mean a method called "method"? What does it do?
Using this:
https://github.com/makhidkarun/py_tools/blob/master/lib/character.py
Line 19 sets "self.skills" either from the passed in data or from
https://github.com/makhidkarun/py_tools/blob/master/lib/character_tools.py
#L34-L48
So Character.skills is a dict with a string key and an int value. I need
to be able to add skills and my first attempt is a function:
https://github.com/makhidkarun/py_tools/blob/master/lib/character_tools.py
#L52-L56
Should the "add_skills" function be a method in the character class or be
made a more generic function to add/modify a key/value pair in a dict that
is an attribute of an instance? Other tasks will require the add/modify
functionality but coding that increases complexity. At least for me,
anyway.
Sorry about being unclear earlier, coffee was still kicking in and I'm
still a newbie that mixes up terms.
I'm pleading "method" as it allows per-class implementation.
Say you use per-career subclasses of a general Character class. There are
default per-career skill sets, but usually a Character can acquire a skill
that is not needed in his career -- with the exception that Rogues cannot
tap dance ;)
Below is a way to implement that with a specialised add_skill() method:
$ cat basic_oo.py
from __future__ import print_function
import random
from collections import defaultdict
class Character(object):
DEFAULT_SKILLS = ['Blade', 'GunCbt', 'Admin', 'Streetwise']
def __init__(self):
self.skills = defaultdict(int)
def add_random_skills(self, terms):
skillnames = self.DEFAULT_SKILLS
for _ in range(2*terms):
self.add_skill(random.choice(skillnames))
def add_skill(self, name, amount=1):
self.skills[name] += amount
def __str__(self):
skills = ", ".join(
"{}={}".format(name, amount)
for name, amount in sorted(self.skills.items())
if amount != 0
)
return "{}({})".format(self.__class__.__name__, skills)
class Rogue(Character):
def add_skill(self, name, amount=1):
if name == "TapDance":
raise ValueError("Sorry, this rogue will never tap dance")
super(Rogue, self).add_skill(name, amount)
class Marine(Character):
DEFAULT_SKILLS = ['GunCbt', 'VaccSuit', 'Leadership', 'Vehicle']
def main():
NUM_CHARACTERS = 5
CHARACTERS = [Marine, Rogue]
characters = [
random.choice(CHARACTERS)() for _ in range(NUM_CHARACTERS)
]
for c in characters:
c.add_random_skills(5)
c.add_skill("RepairBicycles", random.randrange(3))
try:
c.add_skill("TapDance", 3)
except ValueError as err:
print(err)
for c in characters:
print(c)
if __name__ == "__main__":
main()
$ python basic_oo.py
Sorry, this rogue will never tap dance
Sorry, this rogue will never tap dance
Sorry, this rogue will never tap dance
Rogue(Admin=3, Blade=4, GunCbt=2, Streetwise=1)
Marine(GunCbt=5, Leadership=4, TapDance=3, VaccSuit=1)
Rogue(Blade=3, GunCbt=2, RepairBicycles=2, Streetwise=5)
Rogue(Admin=1, Blade=2, GunCbt=5, RepairBicycles=1, Streetwise=2)
Marine(GunCbt=1, Leadership=3, RepairBicycles=2, TapDance=3, VaccSuit=2,
Vehicle=4)
Okay Peter, I took your idea and mangled it beyond recognition. There's
a design constraint I hadn't mentioned: an instance of Character should
be able to have multiple careers.
Also, an instance can be created from scratch, created from a full set
of data, or created from a partial set of data.
Here's my current code, focusing on creating a lot of merchants:
https://github.com/makhidkarun/py_tools/blob/merchant/lib/character.py#L60-L61
python chargen.py
Toby Verstraeten 564775 [M] Age: 41
Merchant (5 terms)
Computer-2 Engineering-5 Navigation-2 Pilot-1
Captain Ian Domici 789987 [M] Age: 24
Firster (3 terms) Merchant (3 terms) Noble (2 terms)
Broker-2 GunCbt-1 Streetwise-2
Rosa 66495B [F] Age: 24
Merchant (1 terms)
Computer-1 Navigation-1
As you can see, lots to work on. However, with a very loose definition
of "work", this works.
The goal is to have a set of Career classes. The program will allow a
user to select one or more Careers. The program will create a basic
character and then modify the character by the selected Career class(es).
If the Career does not exist in a file then the character gets assigned
a generic Career based on social status.
Careers are each in their own file and the program builds the list of
available careers by slurping up those file names.
Adding a Career should just be adding a properly formatted file.
Import happens when a Career is selected to modify the character
I've done this in Ruby so my guess is it can be done in Python. Even
Python 2. :D
The Career seems to be a "Decorator" pattern given my limited
understanding of design patterns. Concur? If so I'll go study that some
more.
Do you feel this path should still make a Career a class?
Thanks!
Leam
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