NML: 16-cargo industry support

[GarryG]

There's nothing wrong with using the current development version to get going

Shhhh .. by waiting for the official release gives me a reason to concentrate on my other projects for now. Besides once I start the Industry set again, I have lots of plans and new ideas.

[Andrew350]

I had a quick question regarding the change to 16-cargo support:

Are the changes savegame-safe?

In other words, if I update an industry NewGRF to use the new NML 0.5 syntax but otherwise don't change it's behavior, will it remain compatible to savegames using that NewGRF with the "old" industry code? My gut says it should be fine, but I don't know how the conversion is handled "under the hood", and while a little bit of testing hasn't revealed any obvious issues, it's hard to say about the effects in the long term. I understand if this is an unknown, but figured I should ask just to be safe

Also, I want to take the opportunity to thank those who worked on this I've been dreading what it would take to convert the old code to the new, only to find out it was in fact extremely easy. The new syntax is not only more powerful but indeed easier to understand and more intuitive, so thank you for the work you do to keep making the game even better

[jfs]

I think the answer is "maybe safe"!
As long as the cargo types for accepts and produces end up declared in the same order (so using the same indexes on the industries) it should be compatible. The question is getting NML to generate the correct order, which I think is possible.

[andythenorth]

My guess would be that the new action 0 props would be missing from the industry instances. AFAICT, they're instantiated when the industry is built in game, and not migrated if the grf changes.

That's my interpretation from changing industries many times, I haven't read the actual OpenTTD code.