Special Functions

Python provides several special functions to get the metadata of the programs that are being executed.

  • __name__ - to get the name of the program

  • All operators are typically nothing but functions. We have already seen operator which contain the functions.

  • All the standard classes have special functions called as __str__ and __repr__ to provide string representation.

  • As we explore collection is future, we will observe special functions for operators such as in, not in, len etc.

  • We can also use functions (constructors) such as int, float, str etc to convert the data types.

print(__name__)

__main__

import operator

operator.add?

Docstring: add(a, b) -- Same as a + b.
Type:      builtin_function_or_method

int.__str__?

Signature:      int.__str__(self, /)
Call signature: int.__str__(*args, **kwargs)
Type:           wrapper_descriptor
String form:    <slot wrapper '__str__' of 'int' objects>
Namespace:      Python builtin
Docstring:      Return str(self).

int.__repr__?

Signature:      int.__repr__(self, /)
Call signature: int.__repr__(*args, **kwargs)
Type:           wrapper_descriptor
String form:    <slot wrapper '__repr__' of 'int' objects>
Namespace:      Python builtin
Docstring:      Return repr(self).

user =  '1,123 456 789,Scott,Tiger,1989-08-15,+1 415 891 9002,Forrest City,Texas,75063'

user.split(',')[0]
# Even though user_id is integer, it will be treated as string
# split converts a string to list of strings

'1'

type(user.split(',')[0])

str

# We can use int to convert the data type of user_id
user_id = int(user.split(',')[0])
user_id

1

type(user_id)

int

int.__repr__?

Signature:      int.__repr__(self, /)
Call signature: int.__repr__(*args, **kwargs)
Type:           wrapper_descriptor
String form:    <slot wrapper '__repr__' of 'int' objects>
Namespace:      Python builtin
Docstring:      Return repr(self).

user =  '1,123 456 789,Scott,Tiger,1989-08-15,+1 415 891 9002,Forrest City,Texas,75063'

user.split(',')[0]
# Even though user_id is integer, it will be treated as string
# split converts a string to list of strings

'1'

type(user.split(',')[0])

str

# We can use int to convert the data type of user_id
user_id = int(user.split(',')[0])
user_id

1

type(user_id)

int
Date Manipulation Functions Exercises