Tuesday, May 14, 2019

Advantage of Python over Java

Here's a question for you: what is the advantage of using Python over Java? Because of the recent publication of the second edition of Extending Art of Illusion I've been spending time working on scripts for Art of Illusion. Straight out of the box, Art of Illusion provides scripting capability for Groovy and BeanShell. This makes sense because Art of Illusion is written in Java and both of these scripting languages are based on Java. But most other graphics programs use some variation on Python as their scripting language. In a post on Python Scripts in Art of Illusion I wrote about creating a plugin that adds Python to the languages that Art of Illusion supports. I use Python for things I do in my day job mostly because it's available. But with adding it to Art of Illusion I have a direct comparison between Java and Python. It got me thinking. Is there some reason to choose to script in Python rather than using Java, Groovy, or BeanShell?

When I setup the interpreter, I did my best to provide consistency between what can be done with Python and what can be done with Groovy. The types of scripts are the same. The editor windows are the same. The libraries linked in from Art of Illusion are the same. I'm using the Jython interpreter, so everything that can be called from a Java class can be called from Python. So, in considering the question it really does come down to language differences.

Groovy and Python handle blocks differently. Java is very similar to C, so a block is whatever is within curly braces. In Python blocks are handled by indenting. There's nothing particularly advantageous for one over the other. It is personal preference. Personally, I've fine with both. Comments are also handled differently. Groovy uses C++ style comments while Python uses # to mark a comment. Again, that's just personal preference. Strings are handled by both and what you can do with strings is very similar.

The biggest difference between Python and Java is that Python has powerful list processing capability built right in while Java treats it as more of an afterthought. Given that 3D graphics scenes are lists of objects and objects are lists of polygons and polygons are lists of vertices, how a scripting language processes lists is important. In Python, a list is denoted by square brackets, []. In Art of Illusion we're most likely to get a list by using values returned from some Java function. In addition to lists, Python has dictionaries (square brackets {}), which are an unordered table that maps keys to values. It also has sets, which are unordered collections of unique objects.

A list might simply be every object in the scene or every object of a certain type and we want to perform some operation on each of the objects in the list. We might use a dictionary if we want to refer to objects by name. Sets are only truly useful in combination. We might have a set of edge vertices and a set of interior vertices. We might have a set of visible vertices and a set of invisible vertices. If we wanted to perform some operation on all of the visible edge vertices then we could get the intersection of the edge vertices set and the visible set and then loop through that set rather than having a check in our loop for whether a set of conditions is met. Of course, it is possible to do this with Java as well, but having it inherent in the language is nice.