#!/usr/bin/env python
# coding: utf-8

# ## Decorators and Functional Programming in Python
# 
# Derived from the notebook: http://anandology.com/nb/2014/decorators-demystified/ (Was a workshop in Pycon India '14)

# In[1]:


def square(x):
    return x*x

print(square(4))


# In[2]:


print(square)


# In[3]:


f = square


# In[4]:


print(f)


# They're called first-class objects

# In[5]:


def sum_of_square(x, y):
    return square(x) + square(y)


# In[6]:


sum_of_square(3,4)


# In[7]:


def sum_of(f, x, y):
    return f(x) + f(y)

sum_of(square, 2, 3)


# In[8]:


def mod3(x):
    return x % 3

sum_of(mod3, 4, 5)


# In[9]:


sum_of(lambda x: x %3, 4, 5)


# In[10]:


mod4 = lambda x: x % 4


# In[11]:


mod4(17)


# In[12]:


print(lambda x: x % 4)


# In[13]:


max(["Python", "Haskell"], key=len)


# In[14]:


print(len)


# In[15]:


len("Python")
print("python" > "haskell")
print(len("python") > len("haskell"))


# In[16]:


def incr(x, amount=1):
    return x + amount


# In[17]:


incr(4)


# In[18]:


incr(4, 2)


# In[19]:


def sub(x, y):
    return x-y


# In[20]:


sub(3, 5)


# In[21]:


sub(x=3, y=5)


# In[22]:


sub(y=5, x=3)


# In[23]:


max(1,2,3,4,5)


# In[24]:


def f(*args):
    print(args)
    
f(2,3,5)
f(8,1)


# In[25]:


def xprint(label, *args):
    print(type(args))
    for a in args:
        print(label, a)


# In[26]:


xprint("Info", 1,2,3)


# 
# 
# **Problem** Implement a function maximum that takes 2 values x and y and a key function as argument and finds the maximum by comparing key(x) and key(y).
# 
#     >>> maximum(3, -4, abs)
#     -4
#     >>> maximum("Python", "Haskell", len)
#     'Haskell'
#     >>> maximum("java", "Python", lambda s: s.lower())
#     'Python'
# 
# 
# 
# **Problem**  Write a function strjoin that takes a separator as first argument followed by variable number of strings to join with that separator.
# ```
# >>> strjoin("-", "a", "b", "c")
# "a-b-c"
# ```
# 

# In[27]:


def maximum(*args, key=lambda x: x):
    best = args[0]
    for i in args:
        if (key(i) > key(best)):
            best = i
    return best


# In[28]:


maximum('aloo', 'python', 'z', 'Haskell', key=len)


# In[29]:


def strjoin(sep, *args):
    return sep.join(args)

strjoin("-", "a", "b", "c")


# In[30]:


# Just like variable args, you can have variable keword args too, just use ** instead of *

def f(**kwargs):
    print(kwargs)


# In[31]:


f(x=1, y=2, abcd=3)


# In[32]:


[int(x) for x in '2 3 4 5'.split()] # List comprehension


# In[33]:


[(k,v) for k, v in {'title': 'IIIT-D', 'href': 'http://iiitd.ac.in'}.items()]


# In[34]:


"Hey %s" % ('jai')


# **Problem** Make a function `render_tag(tagname, **attrs)` that returns a html tag as a string
# 
#     >>> render_tag("a", href="http://iiitd.ac.in", title="IIIT-D")
#     '<a href="http://iiitd.ac.in", title="IIIT-D">'

# In[35]:


def render_tag(tagname, **attrs):
    pairs = ['%s="%s"' % (k,v) for k, v in attrs.items()]
    pairs_str = " ".join(pairs)
    return "<%s %s>" % (tagname, pairs_str)


# In[36]:


render_tag("a", href="http://iiitd.ac.in", title="IIIT-D")


# In[37]:


# Currying
def make_adder(x):
    def add(y):
        return x + y
    return add


# In[38]:


add5 = make_adder(5)
add5(2)


# In[39]:


add6 = make_adder(6)
add6(7)


# In[40]:


make_adder(8)(5)


# ## Decorators

# In[41]:


get_ipython().run_cell_magic('file', 'trace0.py', '\ndef trace(f):\n    def wrapper(*args):\n        print(f.__name__, args)\n        return f(*args)\n    return wrapper\n')


# In[42]:


get_ipython().run_cell_magic('file', 'sum.py', '\nfrom trace0 import trace\n\n@trace\ndef square(x):\n    # print("square", x)a\n    return x*x\n\n#square = trace(square)\n\n@trace\ndef sum_of_squares(x, y):\n    # print("sum_of_squares", x, y)\n    return square(x) + square(y)\n\n#sum_of_squares = trace(sum_of_squares)\n\nprint(sum_of_squares(3,4))\n')


# In[43]:


get_ipython().system('python sum.py')


# In[44]:


get_ipython().run_cell_magic('file', 'trace1.py', '\nlevel = 0\n\ndef trace(f):\n    def wrapper(*args):\n        global level\n        print("|  " * level + "|--", f.__name__, args)\n        \n        level += 1\n        result = f(*args)\n        level -= 1\n        \n        return result\n    return wrapper\n')


# In[45]:


get_ipython().run_cell_magic('file', 'fibo.py', '\nfrom trace1 import trace\nfrom memoize import memoize\n\n@trace\ndef fib(n):\n    if n==0 or n==1:\n        return 1\n    else:\n        return fib(n-1) + fib(n-2)\n    \nprint(fib(7))\n')


# In[46]:


get_ipython().system('python fibo.py')


# In[47]:


get_ipython().run_cell_magic('file', 'memoize.py', '\ndef memoize(f):\n    \n    cache = {}\n    \n    def wrapper(*args):\n        if args not in cache:\n            cache[args] = f(*args)\n        return cache[args]\n    return wrapper\n')


# In[48]:


get_ipython().run_cell_magic('file', 'fibo1.py', '\nfrom trace1 import trace\nfrom memoize import memoize\n\n@memoize\n@trace\ndef fib(n):\n    if n==0 or n==1:\n        return 1\n    else:\n        return fib(n-1) + fib(n-2)\n    \nprint(fib(7))\n')


# In[49]:


get_ipython().system('python fibo1.py')


# **Problem**
# Write a function with_retries that continue to retry for 5 times if there is any exception raised in the function.
# 
# ```
# @with_retries
# def wget(url):
#     return urllib2.urlopen(url).read()
#     
# wget("http://google.com/no-such-page")
# ```
# 
# Should print:
# 
# ```
# Failed to download, retrying...
# Failed to download, retrying...
# Failed to download, retrying...
# Failed to download, retrying...
# Failed to download, retrying...
# Giving up!
# ```

# In[50]:


get_ipython().run_cell_magic('file', 'with_retries.py', '\nimport urllib.request\n\ndef with_retries(f, num):\n    def wrapper(*args):\n        for i in range(num):\n            try:\n                return f(*args)\n            except:\n                print("Failed")\n        print("Given up!")\n    return wrapper\n\n#@with_retries\ndef wget(url):\n    return urllib.request.urlopen(url)\n\nwget = with_retries(wget, 7)\nx = wget("http://google.com/pageisnonexistent")\n')


# In[51]:


get_ipython().system('python with_retries.py')


# In[52]:


get_ipython().run_cell_magic('file', 'with_retries_adv.py', '\ndef with_retries(num):\n    def decor(f):\n        def wrapper(*args):\n            for i in range(num):\n                try:\n                    return f(*args)\n                except:\n                    print("failed")\n            print("given up!")\n        return wrapper\n    return decor\n\n@with_retries(3)\ndef wget(url):\n    return urllib.request.urlopen(url)\n\n# wget = with_retries(3)(wget)\n\nx = wget("http://google.com/pageisnonexistent")\n')


# In[53]:


get_ipython().system('python with_retries_adv.py')


# ## Web framework - JUG (nano flask)

# In[54]:


get_ipython().run_cell_magic('file', 'jug.py', '\nmapping = []\n\ndef route(path):\n    def decor(f):\n        mapping.append((path, f))\n    return decor\n\ndef request(path):\n    for p, func in mapping:\n        if p == path:\n            return func()\n    return "404"\n\ndef wsgifunc(env, start_response):\n    path = env[\'PATH_INFO\']\n    start_response(\'200 OK\', [("Content-Type", "text/plain")])\n    return [request(path).encode(\'utf-8\')]\n\ndef run(port=8080):\n    from wsgiref.simple_server import make_server\n    server = make_server("0.0.0.0", port, wsgifunc)\n    server.serve_forever()\n')


# In[55]:


get_ipython().run_cell_magic('file', 'hello.py', '\nfrom jug import route\n\n@route(\'/hello\')\ndef hello():\n    return "Hello! :D"\n\n@route(\'/bye\')\ndef bye():\n    return "Good bye!"\n')


# In[56]:


get_ipython().run_cell_magic('file', 'client.py', 'import hello\nfrom jug import request, run\nimport sys\n\nif "--web" in sys.argv:\n    run()\nelse:\n    print(request("/hello"))\n    print(request("/bye"))\n')


# In[57]:


get_ipython().system('python client.py')


# In[59]:


get_ipython().system('python client.py --web')


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