The Weather in Deather

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;

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"

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();