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Ch06 3 transaction #2

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Merged
mxv2 merged 3 commits into from
May 28, 2019
Merged

Ch06 3 transaction #2

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a2fb1a8
implement Transaction class
May 19, 2019
c0644b2
fix Transaction#usd calculation
May 22, 2019
0415b98
implement Account class
May 28, 2019
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304 changes: 304 additions & 0 deletions ch06_objects/Account.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,304 @@
import os
import pickle
import tempfile
from datetime import datetime


class AccountError(Exception):
pass


class NoFilenameError(AccountError):
pass


class SaveError(AccountError):
pass


class LoadError(AccountError):
pass


class Account:
"""Account store info about account number, name and list of Transactions
"""

def __init__(self, number, name):
if number is None:
raise ValueError('number should be provided')
self._verify_name(name)
self._number = number
self._name = name
self._transactions = []

def _verify_name(self, name):
if name is None:
raise ValueError('name should be provided')
if len(name) < 4:
raise ValueError('name should be at least 4 characters')

@property
def number(self):
"""
>>> acc = Account(1, 'account')
>>> acc.number
1
>>> acc.number = 100
Traceback (most recent call last):
...
AttributeError: can't set attribute
"""
return self._number

@property
def name(self):
"""
>>> acc = Account(1, 'new account')
>>> acc.name
'new account'
>>> acc.name = 'updated account'
>>> acc.name
'updated account'
>>> acc.name = 'acc'
Traceback (most recent call last):
...
ValueError: name should be at least 4 characters
"""
return self._name

@name.setter
def name(self, name):
self._verify_name(name)
self._name = name

def apply(self, transaction):
if transaction is None:
raise ValueError('transaction should be provided')
self._transactions.append(transaction)

def __len__(self):
return len(self._transactions)

@property
def balance(self):
"""Return balance in USD for all account transactions

>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> acc = Account(42, 'default')
>>> acc.apply(Transaction(100, timestamp))
>>> acc.balance
100.0

>>> acc.apply(Transaction(6250, timestamp, currency='RUB', usd_conversion_rate=62.5))
>>> acc.balance
200.0
"""
balance = 0
for t in self._transactions:
balance += t.usd
return balance

@property
def all_usd(self):
"""Return balance in USD for all account transactions

>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> acc = Account(42, 'default')
>>> acc.apply(Transaction(100, timestamp))
>>> acc.apply(Transaction(100, timestamp))
>>> acc.all_usd
True

>>> acc.apply(Transaction(6250, timestamp, currency='RUB', usd_conversion_rate=62.5))
>>> acc.all_usd
False
"""
for t in self._transactions:
if t.currency != 'USD':
return False
return True

def save(self, filename=None):
"""Save Account state in pickle format

>>> account_name = 'default'
>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> acc = Account(42, account_name)
>>> acc.apply(Transaction(100, timestamp))
>>> acc.apply(Transaction(100, timestamp))
>>> acc.apply(Transaction(6250, timestamp, currency='RUB', usd_conversion_rate=62.5))

>>> tmp_dir = tempfile.gettempdir()
>>> dump_filename = os.path.join(tmp_dir, account_name)
>>> dump_full_filename = dump_filename + '.acc'

>>> acc.save(dump_full_filename)
>>> os.path.exists(dump_full_filename)
True

>>> os.remove(dump_full_filename)

>>> acc.save(dump_filename )
>>> os.path.exists(dump_full_filename)
True

>>> os.remove(dump_full_filename)

>>> acc.save()
>>> os.path.exists(dump_filename + '.acc')
True
"""
if filename is not None:
self.filename = filename
if self.filename is None:
raise NoFilenameError(filename)

if not self.filename.endswith('.acc'):
self.filename += '.acc'

fd = None
try:
fd = open(self.filename, 'wb')
data = (self._name, self._number, self._transactions)
pickle.dump(data, fd, pickle.HIGHEST_PROTOCOL)
except (EnvironmentError, pickle.PicklingError) as err:
raise SaveError(err)
finally:
if fd is not None:
fd.close()

def load(self, filename=None):
"""Load Account state from pickle format

>>> account_name = 'default'
>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> acc = Account(42, account_name)
>>> acc.apply(Transaction(100, timestamp))
>>> acc.apply(Transaction(100, timestamp))
>>> acc.apply(Transaction(6250, timestamp, currency='RUB', usd_conversion_rate=62.5))
>>> tmp_dir = tempfile.gettempdir()
>>> dump_full_filename = os.path.join(tmp_dir, account_name) + '.acc'
>>> acc.save(dump_full_filename)

>>> acc = Account(112, 'new name')
>>> acc.load(dump_full_filename)
>>> acc.name
'default'
>>> acc.number
42
"""
if filename is not None:
self.filename = filename
if self.filename is None:
raise NoFilenameError(filename)

if not self.filename.endswith('.acc'):
self.filename += '.acc'

fd = None
try:
fd = open(self.filename, 'rb')
(name, number, transactions) = pickle.load(fd)
self.name = name
self._number = number
self._transactions = transactions
except (EnvironmentError, pickle.PicklingError) as err:
raise LoadError(err)
finally:
if fd is not None:
fd.close()


class Transaction:
"""Transaction store info about currency transaction
and calculate amount in USD (based on usd_conversion_rate)

usd_conversion_rate for USD must always be equal to 1.0
"""

def __init__(self, amount, date, currency='USD', usd_conversion_rate=1.0,
description=None):
"""
>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> str(Transaction(1, timestamp, currency='USD'))
'1 USD at 2019-05-19 22:20:00'
>>> Transaction(1, timestamp, currency='USD', usd_conversion_rate=10.0)
Traceback (most recent call last):
...
ValueError: USD conversion rate should be equal to 1.0
>>> str(Transaction(1, timestamp, currency='EUR', usd_conversion_rate=1.0))
'1 EUR at 2019-05-19 22:20:00'
>>> Transaction(None, timestamp)
Traceback (most recent call last):
...
ValueError: amount could not be None
>>> Transaction(1, None)
Traceback (most recent call last):
...
ValueError: date could not be None
"""
if amount is None:
raise ValueError('amount could not be None')
if date is None:
raise ValueError('date could not be None')
if currency == 'USD' and not usd_conversion_rate == 1.0:
raise ValueError('USD conversion rate should be equal to 1.0')
self._amount = amount
self._date = date
self._currency = currency
self._usd_conversion_rate = usd_conversion_rate
self._description = description

@property
def amount(self):
return self._amount

@property
def date(self):
return self._date

@property
def currency(self):
return self._currency

@property
def usd_conversion_rate(self):
return self._usd_conversion_rate

@property
def description(self):
return self._description

@property
def usd(self):
"""Return calculated amount in USD

>>> timestamp = datetime(2019, 5, 19, 22, 20, 0)
>>> t = Transaction(1, timestamp)
>>> t.usd
1.0
>>> t = Transaction(6250, timestamp, currency='RUB', usd_conversion_rate=62.5)
>>> t.usd
100.0
"""
return self._amount / self._usd_conversion_rate

def __str__(self):
return '{0} {1} at {2}'.format(
self._amount, self._currency, self._date
)

def __repr__(self):
return ("{0}(amount={1}, date={2}, currency={3}, "
"usd_conversion_rate={4}, description={5})").format(
self.__class__.__name__,
self._amount, repr(self._date), self._currency,
self._usd_conversion_rate, repr(self._description)
)


if __name__ == '__main__':
import doctest

doctest.testmod()