Wednesday, December 14, 2016 Quick Facts

Quick facts on the numpy.ndarray object returned by

  • The array's shape is (height, width, 3)
  • The last shape value of 3 represents three color channels, in RGB order. This is important because OpenCV's imread function gives channels in BGR order.
  • The array has dtype=float32 with values in range 0.0-1.0. Again, this is important because OpenCV's imread function gives an array with dtype=uint8 with values in range 0-255.

I'm publishing this so I don't have to re-learn this "truth" every time I'm dealing with image loading and conversions.

Tuesday, December 6, 2016

What Code Belongs in an MVC Controller

The purpose of a controller is to act as a conduit between each user interaction and system response. Typically this involves three steps:

  • readRequest(). For a web server this means reading the inbound HTTP request, analyzing the headers, taking care of authorization.
  • doSomething(). Now that the server knows what it's being asked to do, the server can go ahead and do something useful.
  • writeResponse(). After the server has finished its job or kicked off a long-running process, it should write a response back to the user to let the user know how things went.

In a different sense, a controller's action method is just a wrapper for a function that executes actual business logic, a wrapper that translates an HTTP request into function args.

This setup makes sense to me, but what other approaches are there to writing good controllers? Please share your comments.