A guide for creating loosely coupled modules

[shawntabrizi]

Given a module A which has a dependency on module B, show how you can build module C which can be swapped with B.

Teaches:

• How to use traits properly
• Required Functions and Implemented Functions
• Making a module have no direct dependency on another module
• Building two modules which satisfy the conditions
• Some live/practical example of swapping the two

[JoshOrndorff]

I'll take this. Here's my plan in case anyone has feedback

• Marketplace module that is basically like craigslist except that it depends on a notion of "reputation system".
• Reputation system is a Trait
• SimpleFeedback module implements Reputation Trait
• BetaFeedback module implements Reputation Trait
• Marketplace can work with either notion of Reputation.

Two reputation systems I mentioned are taken from https://www-users.cs.umn.edu/~weiss039/papers/Trust-Grid2005.pdf

[shawntabrizi]

Sounds a little too complicated to me?

Why not keep it really bare bones. I would think something like a number modifier module, where one module adds to the number, the other subtracts from the number or something.

Something like a beginner and advance reputation system could work here, but making a "marketplace" module should not be an involved part of this process.

[4meta5]

I feel like this could work well with module instancing. I don't fully understand instancing yet, but it seems that srml/balances and srml/collective allow you to create multiple instances of the same module with different configurations. So, for example, if you wanted multiple councils with different voting members and different weighting algorithms. You choose council invocation among the multiple councils based on the nature of voting topics.

[JoshOrndorff]

Here's a start I've been toying with. Learneding a lot along the way. https://github.com/joshorndorff/marketplace

[shawntabrizi]

Do you want / Is it ready for for a code review? How best to give you feedback?

[JoshOrndorff]

@shawntabrizi Feedback welcome at any time. You can comment on my commits or open PRs. It isn't "ready" in the done sense, but there's plenty there. I used your simpler idea as an exercise in substrate collaborative learning today and that code lives https://github.com/JoshOrndorff/state-changer

[shawntabrizi]

I think the simpler one makes a strong foundation for a 1/2 page tutorial imo.

haven't reviewed either yet. will try to find time