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Rust 101 - Session 3

Recap

Ownership

fn main() {
    let nums = vec![2, 4, 6];
 let nums2 = nums;

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package main

import (
	"fmt"
	"strings"
	"syscall"
)

func main() {

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package main

import (
	"fmt"
	"strings"
	"syscall"
)

func main() {

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package main

import (
	"bufio"
	"fmt"
	"net"
	"strconv"
	"strings"
)

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Assume you have a couple of classes,

case class Person(name: String, age: Int)
case class Employee(person: Person, salary: Double)

Lets say for some reason,

• You don't want to change this source, but
• You should be able to add features save(person) and save(employee), and
• You need clearly separate implementations for both the types,

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Prerequisites

Firefox 68.0.1 (64bit) installed from Ubuntu distribution,

Steps to reproduce

1. Copy the files manifest.json and background.js in to a folder
2. Run $ web-ext run
3. In address bar type about:debugging. Temporary extensions 'Test Extension' will be loaded.
4. Click 'Debug'

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Typically, you can't use a 'new' operator on a generic type. This is because of type erasure.

scala> def create[T] = new T
<console>:7: error: class type required but T found
   def create[T] = new T
                       ^

Scala gives a way of getting around this problem, with the Manifest class.

scala> def create[T](implicit m:Manifest[T]) = m.erasure.newInstance

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Keybase proof

I hereby claim:

• I am anoopelias on github.
• I am anoopelias (https://keybase.io/anoopelias) on keybase.
• I have a public key ASBFp65xGHBRZOaP1q61K6Hvb_KSUY9TZzbbnSAh4ythugo

To claim this, I am signing this object:

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use std::cmp::max;

fn largest2(arr: [i32; 5]) -> i32 {
    arr.iter().fold(0, |num, &x| {
        max(num, x)
    })
}

fn largest3(arr: [i32; 5]) -> i32 {
    arr.iter().fold(0, max) // Do Not compile!

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10
14
9 3
2 5
6 5
9 8
0 3
4 7
2 1
0 6