worktoy 0.31.2

Collection of Utilities

WorkToy v0.31.2

Collection of General Utilities

pip install worktoy

Parsing Arguments

In the present version, parse arguments with extractArg:

def func(*args, **kwargs) -> Any:
    """Let us find a str indicating name in these arguments!"""
    nameKeys = stringList('name, identifier, title, target')
    name, args, kwargs = extractArg(str, nameKeys, *args, **kwargs)
    #  And lets find an integer to represent the amount:
    amountKeys = stringList('amount, count, quantity')
    amount, args, kwargs = extractArg(int, nameKeys, *args, **kwargs

In the above example, we used two powerful convenience functions from WorkToy to parse an arbitrary collection of positional and keyword arguments to a str and an int. The stringList splits our text on commas followed by a space, providing:

nameKeys
>>> ['name', 'identifier', 'title', 'target']
amountKeys
>>> ['amount, count, quantity']

In the next part, extractArg finds the first keyword argument from the list of keys that belongs to the type given and returns it. If it finds no such argument, it returns the first positional argument encountered having the indicated type. This allows a great deal of flexibility in how a function is invoked.

The None-aware 'maybe'

In a programming language which shall rename nameless as well as typeless, the following syntax is available:

const func = (arg = null) => {
    let val1 = arg || 1.0;
    let val2 = arg ?? 1.0;
    return [val1, val2]; }

In the above code, the default argument is set to null (in this context null is treated the same as None in Python). The ?? operator is the null-coalescence operator, which is nearly the same as the or operator.
Consider the return value obtained from calling func():

func()
>>> (2)  [1, 1]

This makes sense, but what happens when we call the function on a falsy value other than null, such as 0:

func(0)
>>> (3)  [1, 0]

The first value in the return value comes from using the pipes (the logical or operator), is not aware of the difference between null and other falsy values. The null-coalescence operator is able to tell the difference. The WorkToy module brings this to python along with several derived utility functions:

maybe

In the below python code, we implement the same function using the maybe function from WorkToy:

def func(arg: Any = None) -> Any:
    """Function using the maybe from the WorkToy module"""
    val1 = arg or 1.0
    val2 = maybe(arg, 1.0)
    return [val1, val2]

The implementation of maybe simply follows a common pattern:

def maybe(*args) -> Any:
    """Implementation of maybe returns the first argument given that 
    is different from None. If no such argument is found None is 
    returned."""
    for arg in args:
        if arg is not None: 
            return arg
    return None

Unlike the ?? operator, the maybe operator handles an arbitrary number of arguments.

maybeType

The first of the derived functions finds the first argument of a particular type:

def maybeType(type_: type, *args) -> type_:
    """Returns the first argument of given type"""

maybeTypes

Adding an 's' returns every argument of given type. Further, it supports keyword arguments pad: int and padChar: Any. If pad is given it defines the length of the returned list padded with padChar or None by default. Setting pad will either pad or crop as necessary.