Struct best practices - rianjs/DotNetPerfTesting GitHub Wiki
Guiding principles
- Use structs to represent single notions that require strong typing. Examples: routing numbers, IBAN numbers, coordinates, etc.
- Make them immutable and therefore
readonly- Most types that are used to represent elements of your domain should be immutable whenever possible
- Implement
IEquatable<T>, and implement the==and!=operators - Implement
IComparable<T>if the value has a natural ordering - Most properties should be representable as the application of a function to the underlying value. Or in C# terms: "get-only properties".
- For example, a banking institution's canonical identifier is part of it's routing number, so this property is defined as:
public string AbaInstitutionIdentifier => RoutingCode.Substring(4, 7);
- For example, a banking institution's canonical identifier is part of it's routing number, so this property is defined as:
Struct size
The performance rule of thumb is to keep your structs to 16 bytes (128 bits) or less for regular structs. Regular in this case means non-ref, non-readonly, and not passed with in.
- In a 64-bit application, references require 8 bytes (64 bits)
- 2 references fit inside a struct on a 64-bit machine
- In a 32-bit application, references require 4 bytes (32 bits)
- 4 references fit inside a struct on a 32-bit machine