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Python decorator to turn a function into a variable definition

Project description

vardef: contained and organized variable definition

Usage Examples 🚩 | Developer Reference 👩‍💻 | Authors 👫

vardef is a simple idea for declaring variables in multiple statements in a contained and organized fashion.

A simple Python decorator built with Heart and designed for Humans

from vardef import vardef


vars_defined = 0

@vardef
def somevar() -> int:
    global vars_defined
    vars_defined += 1
    return 42

@vardef
def othervar() -> int:
    global vars_defined
    vars_defined += 1
    return 73

print(vars_defined)
# 2

print(somevar)
# 42

print(othervar)
# 73

print(type(somevar))
# <class 'int'>

print(type(othervar))
# <class 'int'>
from unittest.mock import Mock
from vardef import vardef

from somewhere import User


@vardef
def user_with_read_role() -> Mock:
    user_mock = Mock(User)
    user_mock.roles = ["READ"]
    return user_mock

print(user_with_read_role.roles)
# ['READ']

print(type(user_with_read_role))
# <class 'unittest.mock.Mock'>
import pandas as pd

from butterfree.extract import Source
from butterfree.extract.readers import TableReader
from butterfree.clients import SparkClient
from vardef import vardef


spark_client = SparkClient()

@vardef
def df() -> pd.DataFrame:
    source = Source(
        readers=[TableReader(
            id="colors",
            database="datalake_colors",
            table="colors",
        )],
        query="""
            SELECT * FROM colors
        """,
    )
    return source.construct(spark_client)

df.createOrReplaceTempView("colors")
...
from vardef import vardef


@vardef
def buggy() -> int:
    return 4 / 0

# Traceback (most recent call last):
#   File "./buggy.py", line 5, in <module>
#     def buggy() -> int:
#   File "./vardef/__init__.py", line 7, in vardef
#     return define_var()
#   File "./buggy.py", line 6, in buggy
#     return 4 / 0
# ZeroDivisionError: division by zero

Why to use vardef

  • Organization: using a vardef function allows all necessary code to define and initialize a variable to be logically separated from the outer scope. This makes it clear what code is relevant to the rest of the scope and what code is only there to assist with initialization. Also, in this way, auxiliary code is avoided being exposed to be imported or messed up by external agents.
  • Conciseness: a vardef function is a syntax sugar to avoid the need to declare a function which will only be called once to define a variable. With the decorator your code gets concise and also avoids exposing the initializer function.

For further information on how to use the decorator check out our docs!

Changelog

0.1.0 (2020-12-03)

  • First beta release

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