Add function keyword args and scope

Author: Sahil

day3/functions.py

@@ -0,0 +1,48 @@
+# arguments can be of two types: with default values and without default values
+# those with default values are called keyword arguments
+# for eg the print function we use has 'sep' as a keyword argument which is '\n' by default
+
+# below is also a way you can document your function using docstrings
+def distance_travelled(t, u = 0, g = 9.81):
+  """
+  Function distance_travelled calculates the distance travelled by an object
+  with initial speed u, in a time interval of t, where acceleration due to gravity is g
+
+  input: t (time taken), u (initial speed) g (acceleration due to gravity)
+  output: distance travelled
+
+  Example: 
+      >>> distance_travelled(1.0)
+
+          4.905
+  """
+  d = u*t + 0.5 * g * t**2
+  return d
+
+print(distance_travelled(2.0))
+print(distance_travelled(2.0, u = 1.0))
+print(distance_travelled(2.0, g = 9.7))
+print(distance_travelled(g = 9.7, t = 2.0))
+
+# scope inside a function is different than the one outside it
+# inside function scope, you can access the outer scope variables but cannot change them
+
+def set_name(input_name):
+  name = input_name
+  print(f"Name inside the function: {name}")
+
+set_name("Scaler")
+# print(name) # NameError: this variable is not defined
+
+""" 
+# Exercise: What should be the output for this piece of code?
+def add_char_to_list(char, lst = []):
+  lst.append(char)
+  return lst
+add_char_to_list('s')
+add_char_to_list('c')
+add_char_to_list('a')
+add_char_to_list('l')
+add_char_to_list('e')
+print(''.join(add_char_to_list('r')))
+"""

day3/grid_city.py

@@ -161,11 +161,83 @@ print(res)
 ## More on Functions
 [Code](day3/functions.py)
 
-### Keyword Arguments
+### Keyword Arguments and Positional Arguments
+- A function can have two types of arguments: ones with default values and those without it.
+- The arguments which have a default value are termed as `keyword arguments` and required ones are `positional arguments`.
+- These arguments should always be the last ones, i.e. All the *required (positional) arguments go first*. They are then *followed by the optional keyword arguments*.
+- Arguments without defaults are required otherwise you get a syntax error.
+- You can pass in none, some or all of the keyword arguments.
+- You can pass in parameters by keyword (name defined for argument).
 
+<details>
+<summary>
+Function with keyword arguments (code)
+</summary>
+
+```py
+# for eg the print function we use has 'sep' as a keyword argument which is '\n' by default
+
+# below is also a way you can document your function using docstrings
+def distance_travelled(t, u = 0, g = 9.81):
+  """
+  Function distance_travelled calculates the distance travelled by an object
+  with initial speed u, in a time interval of t, where acceleration due to gravity is g
+
+  input: t (time taken), u (initial speed) g (acceleration due to gravity)
+  output: distance travelled
+
+  Example: 
+      >>> distance_travelled(1.0)
+
+          4.905
+  """
+  d = u*t + 0.5 * g * t**2
+  return d
+
+print(distance_travelled(2.0))
+print(distance_travelled(2.0, u = 1.0))
+print(distance_travelled(2.0, g = 9.7))
+print(distance_travelled(g = 9.7, t = 2.0))
+```
+
+</details>
 
 ### Function scope
 
+```py
+# scope inside a function is different than the one outside it
+# inside function scope, you can access the outer scope variables but cannot change them
+
+def set_name(input_name):
+  name = input_name
+  print(f"Name inside the function: {name}")
+
+set_name("Scaler")
+# print(name) # NameError: this variable is not defined
+```
+
+### Exercise
+
+<details>
+<summary>
+Guess output of the code
+</summary>
+
+```py
+# Exercise: What should be the output for this piece of code?
+# NEVER USE ARGUMENTS WITH LISTS AS DEFAULT VALUES!!!
+def add_char_to_list(char, lst = []):
+  lst.append(char)
+  return lst
+add_char_to_list('s')
+add_char_to_list('c')
+add_char_to_list('a')
+add_char_to_list('l')
+add_char_to_list('e')
+print(''.join(add_char_to_list('r')))
+```
+
+</details>
 
 ## Containers