[REQ] Accessing the parent Cell from a State

[jsoulier]

Is your feature request related to a problem? Please describe.
Yes.

I'd like a way to print the latitude and longitude of the State from the loggers. Currently, I'm writing the lat/long into each State and printing it from there. Since the data is constant (as it is based on the cell position), it should be stored in the Cell instead. However, I can't access the Cell from the State.

Describe the solution you'd like
A way of accessing the parent Cell from a State during printing. Maybe instead of using stream operators, an explicit std::string getString(const State& state, const Cell& parentCell) in the State class would work?

Describe alternatives you've considered

1. Storing the lat/long directly in the States

Thanks

[romancardenas]

Can you work on a PR for this? It's been a while since I don't program in C++, but if I remember correctly, it is possible to define default implementations for these functions right? I'm thinking about backward compatibility: it would be desirable if your new getString function defaults into using stream operations.

[jsoulier]

Yeah I can work on a PR. But AFAIK you can't do a default implementation because States are added as template types i.e. there's no base type for a default implementation.

[jsoulier]

Looking at it now, it would be nice to be able to reference the parent cell at all times, not just while printing. My use case is I'm computing fire spread from cell A to cell B. To compute cell B, I need params from cell A (slope, fuel, etc). Since I only have state A, I need to store slope, fuel, etc in state A. Anything const should be stored in the cells to avoid duplication.

Would storing a const ref to the cell from the state be acceptable? In the state ctor, it could take a cell reference and optionally store that. This would mean removing the default ctor or using pointers instead and allow null cell pointers

[romancardenas]

Give it a try. It should be OK if you don't touch the cell reference. A const pointer should work. Be careful with circular references though, they usually are the source of problems.