Most software projects inadvertently plan to build a throwaway product for delivery to customers, instead of heeding Fred Brooks:
In most projects, the first system built is barely usable…
Plan one to throw away; you will, anyhow.
Luckily, when building Text Collector, only my own management expectations burdened me, so I had an opportunity to build a real pilot and chuck it.
I wrote the pilot in Java and it included all the major features I knew I would need. Thanks to Steve Yegg popping up for the first time in a few years, I heard about Kotlin, so I switched to Kotlin for the real program.
Now that it’s in alpha, I can reasonably compare the size of the two programs:
By many standards, this is small, and smaller yet when you consider that I’ve counted using simply the “wc” command, so the numbers include whitespace and comments.
The pilot included all major functionality, but ignored most edge cases. It featured mms and sms collection with:
- Date filtering
- Message preview (small collections only)
- Pdf creation
- Pdf sharing
- Inline image rendering (no scaling)
- Zooming (without panning or clamping)
For the real program, I kept all the pilot features except contact filtering, added handling for many edge cases, and added features:
- Organization by conversation
- Zip creation
- Reporting usage statistics and errors
- Failure diagnostics and debug features
- Option to cancel collections in progress
- Pre-calculated layout (allows preview for large collection)
So, the Kotlin app has roughly twice the features, with roughly twice the amount of code. At first glance, it doesn’t seem like that significant a difference, but breaking it down this way lets me count up the lines associated with new features only: 1.3 thousand. Thus, the part roughly equivalent to the pilot weighs in at 2.2k lines of Kotlin to Java’s 1.9.
In other words, Kotlin, handling edge cases, is only 15% larger than the equivalent Java that ignores edge cases with wild abandon.
My commit log shows that the Java version took about one month, while the Kotlin version took three. That seems pretty dismal: two thousand lines per month in Java and closer to one thousand in Kotlin, but…
The Java pilot had no tests, the real, Kotlin version adds 6.6 thousand lines worth of test code.