exercism/csharp/the-weather-in-deather

The Weather in Deather

Welcome to The Weather in Deather on Exercism's C# 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

Expression Bodied Members

Many types of struct and class members (fields being the primary exception) can use the expression-bodied member syntax. Defining a member with an expression often produces more concise and readable code than traditional blocks/statements.

Methods and read-only properties are amongst the members that can be defined with expression bodies.

public int Times3(int input) => input * 3;

public int Interesting => 1729;

Conditionals Ternary

Ternary operators allow if-conditions to be defined in expressions rather than statement blocks. This echoes functional programming approaches and can often make code more expressive and less error-prone.

The ternary operator combines 3 expressions: a condition followed by an expression to be evaluated and returned if the condition is true (the if part, introduced by ?) and an expression to be evaluated and returned if the condition is false (the else part, introduced by :).

int a = 3, b = 4;
int max = a > b ? a : b;
// => 4

Throw Expressions

throw expressions are an alternative to throw statements and in particular can add to the power of ternary and other compound expressions.

string trimmed = str == null ? throw new ArgumentException() : str.Trim();

Switch Expressions

A switch expression can match a value to one case in a set of patterns and return the associated value or take the associated action. The association is denoted by the => symbol. In addition, each pattern can have an optional case guard introduced with the when keyword. The case guard expression must evaluate to true for that "arm" of the switch to be selected. The cases (also known as switch arms) are evaluated in text order and the process is cut short and the associated value is returned as soon as a match is found.

double xx = 42d;

string interesting = xx switch
{
    0 => "I suppose zero is interesting",
    3.14 when DateTime.Now.Day == 14 && DateTime.Now.Month == 3 => "Mmm pie!",
    3.14 => "π",
    42 => "a bit of a cliché",
    1729 => "only if you are a pure mathematician",
    _ => "not interesting"
};

// => interesting == "a bit of a cliché"

Instructions

You have been asked to improve some legacy code relating to a weather station.

The weather station accepts readings, and outputs some indicators such as temperature and pressure.

1. Improve the conciseness and readability of appropriate methods

Refactor any appropriate methods of the WeatherStation class using expression bodied members. Use ternary operations and switch expressions where appropriate to improve expressiveness and potentially reduce errors.

Ensure that all tests continue to pass.

Source

Created by

• @mikedamay

Contributed to by

• @ErikSchierboom
• @yzAlvin