UserInputParser

A python module to parse user's input and provide helpful error messages on failure

Read The Documentation

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Usage

Installation

pip install UserInputParser

Then import the package

from inputparser import *

This will make InputParser avalaible as well as all the natively supported validator functions.

Basic Example

from inputparser import *

parser = InputParser("", str, in_list, {"allowable" : ["a", "b", "c", "d"]})

valid = parser.is_valid(input("Select an option: a, b, c, d"))

and on error...

inputparser.inputparser.UserInputError: Provided value of 'e' did not meet the constraints enforced by: in_list(). 
	Arguments passed to constraint function: 
		- allowable : ['a', 'b', 'c', 'd'] 

see more example use-cases

Features

Extensible

Type checking is included by default. If you need something more complex, that's supported too.

Evaluate elements of a list to ensure they meet your specific conditions:

from inputparser import *
 
InputParser(default_val=[], 
            allowable_types=(int, float), 
            constraint_func=are_valid_elements, 
            constraint_args={"element_constraint": in_range,
                             "constraint_args":
                                   {"allowable_range": (0.0, 0.1)}
                            })

or perhaps you want something custom. Provide your own constraint function:

from inputparser import *

# Define your own constraint function
def custom_constraint(val, str_starts_with: str):
    return True if val[0:len(str_starts_with)] == str_starts_with else False

# Create the object 
parser = InputParser(default_val="$0", 
                     allowable_types=str, 
                     constraint_func=custom_constraint, 
                     constraint_args={"str_starts_with": "$"})

Helpful Error Messages

As a user, not knowing where or why your input was wrong is aweful. Or worse, having the program produce wrong results because the user entered a percentage instead of a decimal - but didn't error.

User value provided for interest_rate in ./examples/user_input_example.json is invalid: 
Provided value of '0.2' did not meet the constraints enforced by: in_range(). 
	Arguments passed to constraint function: 
		- allowable_range : (0.0, 0.1) 
		- inclusive : True 

Using default value of 0.0

This even works for custom functions.

Lightweight

UserInputParser has no dependencies to keep your programs fast.