104 lines
3.5 KiB
Markdown
104 lines
3.5 KiB
Markdown
# Name Badge
|
|
|
|
Welcome to Name Badge on Exercism's Elixir Track.
|
|
If you need help running the tests or submitting your code, check out `HELP.md`.
|
|
If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
|
|
|
|
## Introduction
|
|
|
|
## Nil
|
|
|
|
[Nil][nil-dictionary] is an English word meaning "nothing" or "zero". In Elixir, `nil` is a special value that means an _absence_ of a value.
|
|
|
|
```elixir
|
|
# I do not have a favorite color
|
|
favorite_color = nil
|
|
```
|
|
|
|
In other programming languages, `null` or `none` values might play a similar role.
|
|
|
|
## If
|
|
|
|
Besides `cond`, Elixir also provides the macro [`if/2`][getting-started-if-unless] which is useful when you need to check for only one condition.
|
|
|
|
[`if/2`][kernel-if] accepts a condition and two options. It returns the first option if the condition is _truthy_, and the second option if the condition is _falsy_.
|
|
|
|
```elixir
|
|
age = 15
|
|
|
|
if age >= 16 do
|
|
"You are allowed to drink beer in Germany."
|
|
else
|
|
"No beer for you!"
|
|
end
|
|
|
|
# => "No beer for you!"
|
|
```
|
|
|
|
It is also possible to write an `if` expression on a single line. Note the comma after the condition.
|
|
|
|
```elixir
|
|
if age > 16, do: "beer", else: "no beer"
|
|
```
|
|
|
|
This syntax is helpful for very short expressions, but should be avoided if the expression won't fit on a single line.
|
|
|
|
### _Truthy_ and _falsy_
|
|
|
|
In Elixir, all datatypes evaluate to a _truthy_ or _falsy_ value when they are encountered in a boolean context (like an `if` expression). All data is considered _truthy_ **except** for `false` and `nil`. In particular, empty strings, the integer `0`, and empty lists are all considered _truthy_ in Elixir.
|
|
|
|
[nil-dictionary]: https://www.merriam-webster.com/dictionary/nil
|
|
[getting-started-if-unless]: https://elixir-lang.org/getting-started/case-cond-and-if.html#if-and-unless
|
|
[kernel-if]: https://hexdocs.pm/elixir/Kernel.html#if/2
|
|
|
|
## Instructions
|
|
|
|
In this exercise you'll be writing code to print name badges for factory employees. Employees have an ID, name, and department name. Employee badge labels are formatted as follows: `"[id] - name - DEPARTMENT"`.
|
|
|
|
## 1. Print a badge for an employee
|
|
|
|
Implement the `NameBadge.print/3` function. It should take an id, name, and a department. It should return the badge label, with the department name in uppercase.
|
|
|
|
```elixir
|
|
NameBadge.print(67, "Katherine Williams", "Strategic Communication")
|
|
# => "[67] - Katherine Williams - STRATEGIC COMMUNICATION"
|
|
```
|
|
|
|
## 2. Print a badge for a new employee
|
|
|
|
Due to a quirk in the computer system, new employees occasionally don't yet have an ID when they start working at the factory. As badges are required, they will receive a temporary badge without the ID prefix.
|
|
|
|
Extend the `NameBadge.print/3` function. When the id is missing, it should print a badge without it.
|
|
|
|
```elixir
|
|
NameBadge.print(nil, "Robert Johnson", "Procurement")
|
|
# => "Robert Johnson - PROCUREMENT"
|
|
```
|
|
|
|
## 3. Print a badge for the owner
|
|
|
|
Even the factory's owner has to wear a badge at all times. However, an owner does not have a department. In this case, the label should print `"OWNER"` instead of the department name.
|
|
|
|
Extend the `NameBadge.print/3` function. When the department is missing, assume the badge belongs to the company owner.
|
|
|
|
```elixir
|
|
NameBadge.print(204, "Rachel Miller", nil)
|
|
# => "[204] - Rachel Miller - OWNER"
|
|
```
|
|
|
|
Note that it is possible for the owner to also be a new employee.
|
|
|
|
```elixir
|
|
NameBadge.print(nil, "Rachel Miller", nil)
|
|
# => "Rachel Miller - OWNER"
|
|
```
|
|
|
|
## Source
|
|
|
|
### Created by
|
|
|
|
- @angelikatyborska
|
|
|
|
### Contributed to by
|
|
|
|
- @neenjaw |