Tips & tricks

Small idioms with a big payoff.

Switch expressions and pattern matching

Property, positional and relational patterns replace long if/else chains.

string Describe(object shape) => shape switch
{
    Circle { Radius: > 10 } => "large circle",
    Circle c                => quot;circle r={c.Radius}",
    Rectangle(var w, var h) when w == h => "square",
    null                    => "nothing",
    _                       => "unknown shape",
};

Records with with-expressions

Immutable data types with value equality in one line.

public record Money(decimal Amount, string Currency);

var price = new Money(10m, "CAD");
var discounted = price with { Amount = 8m };   // non-destructive copy
Console.WriteLine(price == new Money(10m, "CAD")); // True: value equality

using declarations

No extra braces; disposal happens at the end of the enclosing scope.

await using var conn = new SqlConnection(cs);   // disposed at end of scope
var users = await conn.QueryAsync<User>("select * from users"); // e.g. Dapper

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