# Chapter 7 Becoming Pythonic 82-89
# Priciple of Programming in Python
# Framework / Resource Allocation / Readability

# Variables
# Python
x = 7
y = 3
z = 4
v = False
# Pythonic
x, y, z, v = 7, 3, 4, False

# Temp variable assignment
# Python using temp variables
a = "original"
b = "abstract"
print(a,b) 
temp = a
print(a,b,temp)
tempb = b
print(a,b,temp, tempb)
a = b
print(a,b) 

# Pythonic no temp variables
a,b = "original", "abstract"
print(a,b) # "original", "abstract"
a,b = b,a
print(a,b) # "abstract", "original"

# List comprehension page 82
# Python List
l = [] # empty list in memory
# .append() to assign value
for x in range(10):
    l.append(x)   # [0]
    x += 1 # [0,1,...] # control
print(l)

# Pythonic
# Create the list, add all the elements to the list, store it
lc = [ x + 1 for x in range(10) ] # no append()
print(lc)

# Dictionary Comprehension {key: value} page 84
# Collection {'fname': value} as List
# key fname
# values "Bob", "Mary", "Joe"
# [ {'fname': 'Bob' }, {'fname': 'Mary' }, {'fname': 'Joe' } ]
# Data
names = ["Bob","Mary","Joe"]
# Python
# Create an empty dict
fname_values = []
for name in names:
    fname_name = {'fname': name }
    fname_values.append(fname_name) # loop from controller to object
print(fname_values) # [ {'fname': 'Bob' }, {'fname': 'Mary' }, {'fname': 'Joe' } ]

# Pythonic
# Create the list, add all the dict elements to the list, store it
fname_values = [{'fname': name} for name in names ]
print(fname_values)

# Custom iterators page 85
# Python
class NonPythonicIterable:
    def __init__(self, max):
        self.max = max  # 5  range [0-4]  len(5)

    def interate(self):  # __iter__
        # control variable
        num = 0
        # condition
        while num < self.max: # num < 5
            yield num
            num += 1  # yield no storing var use an increment not an operator
            # num + 1 addition operator for variables

# create and instance of the class
iterator = NonPythonicIterable(5)  # [0,1,2,3]
# not related to python syntax
# test the itertor values
for num in iterator.interate(): # ys is replacing a collection with an iterator object
    print(num)

# Pythonic
# replace interate() with __iter__ and __next__

class PythonicIterable:
    def __init__(self, max):
        self.max = max  # 5  range [0-4]  len(5)
        # control variable
        self.num = 0

    def __iter__(self):
        return self
        # 1. removed the control num = 0 to __init__
        # 2. removed operation to __next__

    def __next__(self):
        if self.num < self.max:
            num = self.num
            self.num += 1 # increment
            return num # if for or while
        raise StopIteration

# Program
# create an instance of the PythonicIterable Class
iterator = PythonicIterable(5)
for n in iterator:  # n is local variable in the for scope
    print(n)