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Garage Door Opener – Storing the configuration II

I wrote about my “generic” config class in a previous build log, and alluded to how I wasn’t really sure it was the best plan of attack.

It wasn’t.

All of the casting was painful, the setup was annoying and unnecessary (From both a memory and CPU time POV) – there was little (if any) advantage in using it.

In the end, I wrote a concrete class with mutators for each attribute. This meant each attribute is already the correct type, so there was no annoying casting, and I could control and optimise the serialisation and deserialisation.

You can see the class on Github.

The mutators are pretty straight forward, as is the serialisation:

The boolean values (as well as encryption mode and mqtt Auth mode) are compacted using bit-masks, effectively fitting five config items into one byte. Next, I store single integer and double integer values (I use doubles for port numbers), and finally strings.

The strings are encoded by putting their length in the first byte, effectively limiting string length to 255 characters, which is fine – DNS names are limited to this, and that is the biggest thing the config will store. It also makes it possible to avoid overruns, as we have an effective upper limit, so if we go past that index, we know something is broken.

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