This is a contest, open to programming languages from all nations, to write modular and extensible code to solve the following problem: Implement a service that can run queries on a database.
Sounds simple right? Wrong! A programmer without control over the source-code of that service must be able to later add enhancements such as statistics collecting, timeouts, memoization, and so forth. There are a few more requirements:
- the “enhancements” must be specified in a configuration object which is consumed at run-time (e.g., it could be based on user-input).
- The enhancements are ordered (stats collecting wraps timeouts, not the other way around) but it must be possible to reverse the order of the enhancements at run-time.
- The enhancements must be “surgical” and not “global”. That is, it must be possible to simultaneously have two query services, one reversed and one not reversed, and even have a query service without any enhancements.
Most programming contests emphasize things that are not modularity. This contest emphasizes things that are modularity. And its the olympics and don’t you want to be olympic? So go ahead and prove to the world that Design Patterns are no longer necessary, or that Haskell is the raddest thing since the movie Rad, or that Peanut Butter is better than Jelly. This is much more fun than inflamatory blog posts and angry reddit comments, yes? Yes.
Fork this gist!!
Your program must produce exactly this output. Note the reversing order of the enhancements and the memoization of Query instantiation:
Forward:
Instantiating Query Object
Selecting SELECT ... FROM ... FOR UPDATE ... on #<Object:0x11f6750>
Did not timeout! Yay fast database!
Measured select at 1.00 seconds
Instantiating Query Object
Executing INSERT ... on #<Object:0x11f6750>
Did not timeout! Yay fast database!
Measured select at 1.00 seconds
Executing INSERT ... on #<Object:0x11f6750>
Did not timeout! Yay fast database!
Measured select at 1.00 seconds
Backward:
Instantiating Query Object
Selecting SELECT ... FROM ... FOR UPDATE ... on #<Object:0x11f4ea0>
Measured select at 1.00 seconds
Did not timeout! Yay fast database!
Instantiating Query Object
Executing INSERT ... on #<Object:0x11f4ea0>
Measured select at 1.00 seconds
Did not timeout! Yay fast database!
Executing INSERT ... on #<Object:0x11f4ea0>
Measured select at 1.00 seconds
Did not timeout! Yay fast database!