formula-prompt 0.0.2

A small library to lets you define formulas that you can evaluate in your terminal.

Formula Prompt

This library let's you define formulas that you can later evaluate in your command line. I use this library for school work that requires doing repetitive calculations or calculations needing a computer.

Example

Here's how you'd define formulas to find the volume of a cube and rectangular prism.

from formula_prompt import *

# 1. Define your formulas
@register_formula([NumInput("side length")])
def volume_of_cube(s):
    return s ** 3

@register_formula([
    NumInput("length"),
    NumInput("width"),
    NumInput("height")
])
def volume_of_rectangular_prism(length, width, height):
    return length * width * height

# 2. Start the command line prompt
launch_prompt()

When you run this file, a prompt will let you evaluate your formulas. Here's what it looks like!

0:	volume_of_cube
1:	volume_of_rectangular_prism
Pick a formula:
>>> 0
Input side length:
>>> 2
volume_of_cube:
8.0

Press enter to run again...
>>> 

For more examples, look at the examples folder on GitHub.

Usage details

Installation

Simply run: pip install formula-prompt

Setting up your code

To use this library:

1. Define your functions for each of your formulas. Don't worry about reading user input, this is handled by the library!

2. Add the @register_formula(...) decorator to your function. This will register you function will the library.

3. Run launch_prompt() to start the prompt.

Using @register_formula(...)

This is where the good stuff happens!

@register_formula(...) is a decorator that takes in a list of objects that describe the inputs to your formula.

These objects can be instance of the following classes:

• NumInput: For inputs that accepts a single floating-point number.

• IntInput: For inputs that accept a single integer.

• ListInput: For inputs that accept a list of floating-point numbers.

You can use optional=True to allow skipping the input (this will pass None to your function).

Here's an example.

@register_formula([
    IntInput("first optional input", optional=True),
    NumInput("second non-optional input")
])
def some_funtion(...):
    ...

Advanced details

• If ListInput, IntInput or NumInput don't meet your needs, you can define a custom class that inherits from Input and implements process(). Look at how NumInput is implemented for an example.

• You can specify the number of decimals to round the result to by either a) overwriting the global variable DEFAULT_NUMBER_OF_DECIMALS or by b) passingdecimal_places= as an argument to the @register_function(...) decorator. To not round the result, set the argument to None.

• If your function only has one input, you don't need to pass in a list. For example, @register_formula(NumInput("x")) works the same as @register_formula([NumInput("x")])