implement `get_tmp_cache`

[ranocha]

This function is required for some interoperability with Trixi.jl.

CC @jmbender

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.09%. Comparing base (6845b50) to head (787d8a5).

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```diff @@ Coverage Diff @@ ## main #113 +/- ## ======================================= Coverage 98.09% 98.09% ======================================= Files 6 6 Lines 1414 1420 +6 ======================================= + Hits 1387 1393 +6 Misses 27 27 ```

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[ranocha]

Do you understand the error below, @SKopecz?

┌ Error: failed to run `@example` block in src/index.md:173-178
│ ```@example SIR
│ using Plots
│ 
│ plot(sol, label = ["S" "I" "R"], legend=:right)
│ plot!(sol, idxs = ((t, S, I, R) -> (t, S + I + R), 0, 1, 2, 3), label = "S+I+R") #Plot S+I+R over time.
│ ```
│   exception =
│    Incorrect specification of `idxs`

I have not changed this part of the docs and it worked before...

[JoshuaLampert]

You could test that by forcing SciMLBase@2.44.0.

[ranocha]

Good idea. It's running in #114

[ranocha]

Yes, that's the issue: https://github.com/SciML/SciMLBase.jl/issues/746

[ranocha]

Re-running CI so that we can check the results with the latest version of SciML including a bug fix.

[ranocha]

No, didn't help...

[SKopecz]

I'd suggest to discard the line plot!(sol, idxs = ((t, S, I, R) -> (t, S + I + R), 0, 1, 2, 3), label = "S+I+R") in the docs. I find the syntax idxs = ((t, S, I, R) -> (t, S + I + R), 0, 1, 2, 3) rather cumbersome. Instead we could use something like

plot!(sol.t,sum.(sol.u), label = "S+I+R")

[ranocha]

I'd suggest to discard the line plot!(sol, idxs = ((t, S, I, R) -> (t, S + I + R), 0, 1, 2, 3), label = "S+I+R") in the docs. I find the syntax idxs = ((t, S, I, R) -> (t, S + I + R), 0, 1, 2, 3) rather cumbersome. Instead we could use something like

plot!(sol.t,sum.(sol.u), label = "S+I+R")

Done in https://github.com/SKopecz/PositiveIntegrators.jl/pull/113/commits/787d8a5a73b7bf3e89b0b058d388090cddd94b9e