smartwrappers 0.0.5

A Python 3 library to manipulate objects with shared mutable wrappers

SmartWrappers

A Python 3 library to manipulate objects with shared mutable wrappers.

Installing

Python 3.6.8 or higher is required

To install the library, you can just run the following command:

# Linux/macOS
python3 -m pip install -U smartwrappers

# Windows
py -3 -m pip install -U smartwrappers

Cases to use

# We cannot change immutable objects.
# Trying to change them we just create other objects.

def plus_five(x):
    x += 5  # Creating another object here.

x = 1
plus_five(x)
print(x)  # >>> 1

# Standard solution: rewrite our code in a way our function
# calculates a new value and then we just reassign it to variables
# whose values we need to change.

def get_plus_five(x):
    return x + 5

x = 1
x = get_plus_five(x)
print(x)  # >>> 6

What if we have many objects of the same value and want them to have common state?

a = 1
b = a
c = b
# ...

a = get_plus_five(a)
# What about b, c and other links
# at different places of our project?

Usage

We can use smart wrappers for that purpose:

from smartwrappers import wrap

a = wrap(1)  # or explicitly a = SmartWrapper(1)
b = a
c = b

print(a())  # >>> 1
print(b())  # >>> 1
print(c())  # >>> 1

a(5)
print(a())  # >>> 5
print(b())  # >>> 5
print(c())  # >>> 5

def plus_five(x):
    x(x() + 5)

plus_five(a)
print(a())  # >>> 10
print(b())  # >>> 10
print(c())  # >>> 10

Matrices

We can use smart wrappers for wrapping lists:

from smartwrappers import wrap_list

a = wrap_list([1, 2, 3])
b = [a[0], a[1], a[2]]
print(a)  # >>> [1, 2, 3]
print(b)  # >>> [1, 2, 3]

a[1] = 'a'
print(a)  # >>> [1, 'a', 3]
print(b)  # >>> [1, 'a', 3] => wrappers behave like references to mutable content.

We can wrap lists with any levels of dimensions:

a = wrap_list([[1, 2], [3, 4]], dimensions=2)
b = [[a[0][0], a[1][0]], [a[0][1], a[1][1]]]  # Transposed matrix.

#  a is:
#        1 2
#        3 4
#  b is transposed matrix a:
#        1 3
#        2 4

a[0][1](0)

#  a is:
#        1 0
#        3 4
#  b keeps changes:
#        1 3
#        0 4

If we don't want to put inside our wrapper values of different types we can use StrictSmartWrapper:

from smartwrappers import wrap_strictly

a = wrap_strictly('hello', str)
a('world')  # OK.
a(5)  # Error.
b = wrap_strictly('hello', int)  # Error.