Protocol Buffers

A question came up on Stack Overflow yesterday which I’ve had to deal with myself before now. There are times when it’s helpful to have one value per type, and that value should be an instance of that type. To express it in pseudo-code, you want an IDictionary<typeof(T), T> except with T varying across all possible types. Indeed, this came up in Protocol Buffers at least once, I believe. .NET generics don’t have any way of expressing this, and you end up with boxing and a cast. I decided to encapsulate this (in MiscUtil of course, although it’s not in … Continue reading Mapping from a type to an instance of that type

In the first part of this series we saw that a message type and its builder are closely related. The tricky bit comes when we want to define an interface describing messages and builders. Although some members clearly depend on the data being built (the first and last name in the person example above, for instance) others apply to all messages or all builders. For instance, a message can always provide you with a suitable builder, and a builder always allows you to build it to create the actual message. Likewise the message and builder types also have methods which … Continue reading Lessons learned from Protocol Buffers, part 2: self-referential generic types

My port of the Protocol Buffers project has proved pretty interesting. I thought I’d share some of the lessons I’ve learned along the way, as well as some of the frustrations at concepts I still can’t express in C#. This was originally all going to be in one post, but I’m becoming acutely aware of how long some posts can grow. I don’t know about you, but I find very long blog posts quite intimidating, so I’ve decided to split them up into individual topics. You’ll still probably need to read the posts in order to understand them though – … Continue reading Lessons learned from Protocol Buffers, part 1: messages, builders and immutability