History

One way to ensure things do not go off course is to secure an architecture. So, we will enforce some invariants on the system. We will use the term “invariant” to refer to the set of rules we want to enforce on the system. The idea is that if we can prove the system satisfies these invariants, we can be certain it will behave in a specific way. We should establish this invariant now, not later. The reason is that if we set it later, we don’t know when! So, it will be never when it can be later than any time! We will have to change the code to satisfy the invariant, and the later we set it, the harder it is to satisfy. So, not a second later—right now! ...

Imagine a Python script which gets an HTML file, reads it, and does some calculations then writes it to a new HTML file. The HTML is sent to a web browser by a Python script. Then the web browser modifies the HTML and sends it back to the Python script. The Python script looks at this this HTML and a few other HTMLs and does some calculations and writes a new HTML file. The Python script can also write a new Python script and replace itself for the next run or just keep running unchanged. This process goes back and force between a Python script which produces a python script and html and the web browser which modifies the HTML in return. ...