StackEval

User Question

How to create a list of lists where each sub-list 'increments' as follows: [1, 0, 0], [1, 1, 0], [1, 1, 1]. This works but is unwieldy and not very 'Pythonic'. I'd also like to be able to run through different values for 'numValues', say 4 to 40.

innerList = []
outerList = []
numValues = 12
loopIter = 0

for i in range(numValues):
    innerList.append(0)

for i in range(numValues):
    copyInnerList = innerList.copy()
    outerList.append(copyInnerList)

for i in range(len(innerList)):
    for j in range(loopIter + 1):
        outerList[i][j] = 1
    loopIter += 1

print(outerList)

User Question

How to fix String field does not implement Copy? I am building a simple command-line todo app in Rust. If I don't implement the copy trait I get this error: move occurs because 'todo' has type 'todo::Todo', which does not implement the 'Copy' trait. When I try to implement the Copy trait for my Todo struct, I receive the following error: field text: String does not implement the Copy trait. How do I fix this error? My code is below:

pub type todo_type = Vec<Todo>;

#[derive(Copy)]
pub struct Todo {
    id: usize,
    text: String,
    completed: bool,
}

impl Todo {
    pub fn new(text: String, id: usize) -> Todo {
        Todo {
            text,
            id,
            completed: false,
        }
    }
}

pub struct Todos {
    todos: todo_type,
}

impl Todos {
    pub fn new(todos: todo_type) -> Todos {
        Todos { todos }
    }

    pub fn get_all_todos(self) -> todo_type {
        self.todos
    }

    pub fn get_single_todo(self, todo_index: usize) -> Todo {
        unimplemented!()
    }

    pub fn add_todo(self, text: String) -> Todo {
        let id: usize = 1;

        if self.todos.len() == 0 {
            let id = 1;
        } else {
            let last_todo = match self.todos.len() {
                0 => None,
                n => Some(&self.todos[n - 1]),
            };
            let id = last_todo.unwrap().id;
        }

        let todo = Todo::new(text, id);
        self.todos.push(todo);

        todo
    }

    pub fn remove_todo(self, todo_index: usize) -> bool {
        self.todos.remove(todo_index);

        true
    }
}

User Question

Koa + TypeScript: Property 'body' does not exist on type Request. I wanted to use koa & koa-bodyparser with TypeScript but whenever I access ctx.request.body I get an error that body doesn't exist on type Request.

import Koa from 'koa'
import Router from 'koa-router'
import bodyparser from 'koa-bodyparser'

const app = new Koa()
const router = new Router()

const data = ['lorem', 'ipsum', 'dolor', 'sit', 'amet']

app.use(bodyparser())
router.post('/', (ctx, next) => {
    const phrase = ctx.request.body; // Property 'body' does not exist on type Request
    if (typeof phrase === 'string') {
        ctx.response.body = data.filter(element => element.includes(phrase))
    }
})

User Question

How to implement Comparable so it is consistent with identity-equality? I have a class for which equality (as per equals()) must be defined by the object identity, i.e. this == other. I want to implement Comparable to order such objects (say by some getName() property). To be consistent with equals(), compareTo() must not return 0, even if two objects have the same name.

Is there a way to compare object identities in the sense of compareTo? I could compare System.identityHashCode(o), but that would still return 0 in case of hash collisions.