[comment]: # "markdown: { smartypants: true }" ## Shadowing

### Useful Links <small>Slides: <a href="https://beyondcodebootcamp.github.io/">https://beyondcodebootcamp.github.io/</a></small> <small>Video: <a href="https://youtube.com/coolaj86">https://youtu.be/ID_GOES_HERE</a></small>

AJ ONeal <br> [@\_beyondcode](https://twitter.com/@_beyondcode) <br> [youtube.com/coolaj86](https://youtube.com/coolaj86)

Dangerous Wrong Thinker Equal Opportunity Offender Technophobic Technologist Extraordinairé

Utah Node.js Utah Rust Twitch.tv/coolaj86

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# Shadowing

When you want to _reuse_

When you want to _reuse_ the _name_ of a variable.

```rs [1-2] let answer = "42"; let answer = answer.parse::<i32>().unwrap(); ```

## Scenario

All command line args are _strings_.

(even when they're numbers)

```rs [1-7] let ageStr = env::args().skip(1).next() .unwrap(); println!("age: {}", age); let ageNum = ageStr.parse::<i32>() .unwrap(); println!("age: {}", age); ```

```rs [1] let ageStr = env::args().skip(1).next() .unwrap(); println!("age: {}", age); let ageNum = ageStr.parse::<i32>() .unwrap(); println!("age: {}", age); ```

```rs [5] let ageStr = env::args().skip(1).next() .unwrap(); println!("age: {}", age); let ageNum = ageStr.parse::<i32>() .unwrap(); println!("age: {}", age); ```

But

storing _type information_ in a _name_

... is lame.

```rs [1-11] // type of 'age' is string let age = env::args().skip(1).next() .unwrap(); println!("age: {}", age); // different memory location for new 'age', as int! // (the other age may still be useful through other references) let age = age.parse::<i32>() .unwrap(); println!("age: {}", age); ```

```rs [1-2] // type of 'age' is string let age = env::args().skip(1).next() .unwrap(); println!("age: {}", age); // different memory location for new 'age', as int! // (the other age may still be useful through other references) let age = age.parse::<i32>() .unwrap(); println!("age: {}", age); ```

```rs [6-8] // type of 'age' is string let age = env::args().skip(1).next() .unwrap(); println!("age: {}", age); // different memory location for new 'age', as int! // (the other age may still be useful through other references) let age = age.parse::<i32>() .unwrap(); println!("age: {}", age); ```

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Thanks.

FIN