Exercise Proposal: HTTP Query string builder

[mglodack]

I've recently taken on the challenge of creating a query string builder, and I found it to be a rewarding exercise.

This is an exercise that I enjoy doing whenever I learn a new language and would like to share it.

Exercise:

Write a program that provided a list of tuples can return a HTTP query string.

For example: (Rust-specific)

Input: 
let params = vec![("key1", "value1"), ("key2", "value2")];

Output: 
"?key1=value1&key2=value2"

[IanWhitney]

I haven't spent much time building query strings, are there weird edge cases to this exercise? Like handling quoted keys/values, etc?

[NobbZ]

All characters used to build the query string itself as well as characters which have special meaning in an URL/URI needs to be escaped.

First comming to my mind (because seen very often) is %20 (aka space).

[IanWhitney]

Sure. Do we expect students to implement their own escaping functions, or rely on built-in libraries? Writing their own is probably more useful in terms of learning.

In terms of edge cases, what I'm trying to find here is a progression of complexity, since I find exercises with progression to be more interesting than those that don't. So if our test cases could look like

• single key/value
• double key/value
• edge case 1
• edge case 2
• etc.

Then I think it's great. But if it's something like Gigasecond, where there are no real edge cases and all the tests pass as soon as you get the first test passing, then I find the exercise less intriguing.

This is all my opinion. I have no actual authority here.

[mglodack]

@IanWhitney Thank you for providing such great feedback. I completely agree with you that exercise with a progression of complexity are more interesting.

With regards to what functions the students should use, I believe that is entirely up to the student.

Sometimes, I write my own functions then come to realize there is a library that already exists for it. What happens then?

1. I've learned a lot more than I initially thought I would
2. If the lib is open source I now have something to compare against

Comparing solutions and getting deep into language specific functionality, I think are what exercism does extremely well.

@NobbZ Is absolutely correct that you have to escape special characters.

For now, I'm going to create a more detailed exercise proposal that has some sort of progression of complexity. Then I will paste it back here for some more feedback. 😄

[IanWhitney]

Looking forward to it! Thanks.

[wobh]

If anyone on the exercism/elisp team wants to get a jump on this, I wrote one here: https://github.com/wobh/uri-scribe

Has tests!