helping-hand is based on the go library kele/hand, which appeared on page 36 of issue #3 of Paged Out!
from the original repo:
Imagine you process lots of data. From time to time, though, the data entries are a bit tricky to handle. Writing code that handles them would require a lot of effort… but you could easily handle these individual cases yourself, because you are a human.
using it is very simple:
// given
fn parse_num(s: &str) -> Result<u8, ParseIntError> {
s.parse()
}
// change from:
let result = parse_num("1").unwrap();
// to:
let result = help_with(parse_num)("1").unwrap();if the function passed to help_with returns an error, help_with will very nicely ask you to manually provide the corresponding value
for example, running examples/parsing_numbers.rs will print the following, and then stop, waiting for input:
1
2
Error with input "three": ParseIntError { kind: InvalidDigit }
Fix:
you can then type the correct value using json, followed by EndOfFile (usually Ctrl+D).
this value will get parsed using the type’s serde::Deserialize implementation.
if in this example we type 3 followed by Ctrl+D, the program continues running, and the complete output ends up being:
1
2
Error with input "three": ParseIntError { kind: InvalidDigit }
Fix: 3
3
4
since you can type json, the function passed to help_with can return any type that implements Deserialize, like in examples/complex_type.rs, the output of which is (user input has been surrounded by <>):
hello
worldworld
Error with input "this has a semicolon instead!; 4": "incorrect number of commas"
Fix: <{"string": "this has a semicolon instead!", "times": 4}>
this has a semicolon instead!this has a semicolon instead!this has a semicolon instead!this has a semicolon instead!