Consider Removing IComponentCollection (v4)

[Chris3606]

Currently, the component system in GoRogue has IComponentCollection, which is really just an interface used for an implementation of a collection of components. It also provides ComponentCollection, which is a concrete implementation of that interface.

However, it may be worth considering removing IComponentCollection and simply providing ComponentCollection instead. I'm not aware of very many use cases where a custom implementation of IComponentCollection is the correct answer to a problem, since ComponentCollection is quite efficient and versatile. Futhermore, if ComponentCollection.GetAll<T> uses a custom enumerator (which is coming in a PR soon), accessing GetAll through an interface reference is actually significantly slower, since it requires boxing.

If there is a compelling use case for IComponentCollection, I will happily leave it; but I simply haven't seen a use case that I can recall where it solved a problem; and if it solves a non-existent problem and also costs performance, it would make sense to remove it.

[Chris3606]

Adding some performance tests that back this up:

The version of ComponentCollection in beta5 uses a custom iterator for GetAll. The following benchmarks that implementation:

Method	TypesOfComponents	ComponentsPerType	Mean	Error	StdDev
GetAllMockA	1	2	40.04 ns	0.808 ns	0.930 ns
GetAllMockAViaInterface	1	2	92.37 ns	0.324 ns	0.270 ns
GetAllIMock	1	2	41.74 ns	0.423 ns	0.375 ns
GetAllIMockViaInterface	1	2	99.77 ns	1.441 ns	1.203 ns
GetAll2MockA	1	2	57.40 ns	1.104 ns	1.133 ns
GetAll2MockAViaInterface	1	2	67.15 ns	0.460 ns	0.384 ns
GetAll2IMock	1	2	63.50 ns	1.108 ns	1.037 ns
GetAll2IMockViaInterface	1	2	77.80 ns	0.367 ns	0.286 ns
GetAllMockA	1	10	62.71 ns	0.242 ns	0.202 ns
GetAllMockAViaInterface	1	10	204.15 ns	0.646 ns	0.539 ns
GetAllIMock	1	10	87.27 ns	0.512 ns	0.427 ns
GetAllIMockViaInterface	1	10	241.40 ns	0.895 ns	0.747 ns
GetAll2MockA	1	10	140.73 ns	0.703 ns	0.623 ns
GetAll2MockAViaInterface	1	10	150.34 ns	1.819 ns	1.702 ns
GetAll2IMock	1	10	174.75 ns	0.571 ns	0.506 ns
GetAll2IMockViaInterface	1	10	193.57 ns	0.297 ns	0.232 ns
GetAllMockA	2	2	37.46 ns	0.181 ns	0.160 ns
GetAllMockAViaInterface	2	2	91.72 ns	1.025 ns	0.959 ns
GetAllIMock	2	2	59.91 ns	0.999 ns	0.934 ns
GetAllIMockViaInterface	2	2	137.84 ns	0.317 ns	0.248 ns
GetAll2MockA	2	2	56.13 ns	0.259 ns	0.229 ns
GetAll2MockAViaInterface	2	2	67.87 ns	0.703 ns	0.587 ns
GetAll2IMock	2	2	93.69 ns	0.846 ns	0.750 ns
GetAllMockA	2	10	58.19 ns	0.157 ns	0.123 ns
GetAllMockAViaInterface	2	10	202.02 ns	0.342 ns	0.286 ns
GetAllIMock	2	10	167.17 ns	0.422 ns	0.374 ns
GetAllIMockViaInterface	2	10	426.41 ns	2.096 ns	1.750 ns
GetAll2MockA	2	10	141.43 ns	1.630 ns	1.525 ns
GetAll2MockAViaInterface	2	10	147.20 ns	1.177 ns	1.043 ns
GetAll2IMock	2	10	313.42 ns	3.609 ns	3.199 ns
GetAll2IMockViaInterface	2	10	339.23 ns	1.494 ns	1.324 ns

"GetAll" represents the current, custom enumerator version, both called via a concrete variable of type ComponentCollection, and on that same instance but via an interface. The GetAll2 implementation is an alternate implementation which uses yield return, rather than a custom enumerator, which keeps the interface version closer time-wise, but is slower overall. In both cases, however, the interface is slower.