Module show_notes::e003

No. more. nulls.

• Date: October 21, 2015
• Subject: Enumerated (enum) types, pattern matching, and meaningful return values.
• Audio

Notes

Today’s episode discusses, in order:

• Enumerated types, with an eye to the difference between structs and enums, and to the differences between enums in C and in Rust.
• Pattern matching, with a focus on using them with enumerated types and some discussion about how they differ from switch blocks in C-like languages.
• Using the Option and Result enumerated types with pattern matching to provide meaningful returns from functions safely.

Order

There is a specific order to the examples below, and it is not the automatically-alphabetized order rendered by rustdoc. Instead, you should work through in the sequence they appear in the source:

1. RelatedishThings
2. demonstrate_basic_enumeration
3. demonstrate_match
4. get_an_option
5. demonstrate_option
6. get_a_result
7. demonstrate_result

Links

• New Rustacean Pull Request #1
• Work on IDE support!
  • Landing page
  • My chosen tool: JetBrains/IntelliJ
• Rustlings
• Rust FFI Omnibus

Follow/Support

• New Rustacean:
  • Twitter: @newrustacean
    • App.net: @newrustacean
    • Patreon
  • Email: hello@newrustacean.com
• Chris Krycho
  • Twitter: @chriskrycho
    • App.net: @chriskrycho

Structs

• PreexistingStruct
  Just exists to be used as an element in RelatedishThings.

Enums

• RelatedishThings
  An enumeration can hold a variety of types. This one shows you a few.

Functions

• demonstrate_basic_enumeration
  Shows how the result of an enum comes back as increasingly complex data.
• demonstrate_match
  Shows in a bit more detail how match works.
• demonstrate_option
  Shows how an option type works in practice.
• demonstrate_result
  Shows how a Result type works in practice.
• get_a_result
  Shows how to return either a meaningful result or an error as an enum.
• get_an_option
  Shows how this is used in a more meaningful context, with a standard type.
• get_complex_data 🔒
  Shows how returning a RelatedishThings::ComplexData instance works.
• get_name 🔒
  Shows how returning a RelatedishThings::SomeName instance works.
• get_reused_structure 🔒
  Shows how returning a RelatedishThings::ReusedStructure instance works.
• get_unit 🔒
  Shows how returning a RelatedishThings::Unit instance works.
• get_value 🔒
  Shows how returning a RelatedishThings::SomeValue instance works.