Enrich document with using getter function over state struct instance

[haoyang9804]

Inspired by this issue: #15525. I guess it's better to add a document for this special return type since it's truly confusing.

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[cameel]

Just a note on general structure here: the section on getters is already a bit too verbose IMO, with a lot of space and examples given to what are essentially obscure corner cases. I think we shouldn't make it even longer. We should consolidate the examples and make text more coherent. The focus should be kept primarily on explaining what getters are, the other things are just notes.

[haoyang9804]

Just a note on general structure here: the section on getters is already a bit too verbose IMO, with a lot of space and examples given to what are essentially obscure corner cases. I think we shouldn't make it even longer. We should consolidate the examples and make text more coherent. The focus should be kept primarily on explaining what getters are, the other things are just notes.

How about merging struct example and mapping example? They are all corner cases that can lead to confusion.

[cameel]

Yes, they should be consolidated IMO. We could have just one example showing them all. Or even just a general description of how the ABI for a getter looks like. Which is relevant e.g. when you want to override a function with a getter and should be mentioned too.

[haoyang9804]

Yes, they should be consolidated IMO. We could have just one example showing them all. Or even just a general description of how the ABI for a getter looks like. Which is relevant e.g. when you want to override a function with a getter and should be mentioned too.

Good suggestion. But I can only help with the consolidation part. I'm not very familiar with ABI.

[haoyang9804]

I think the Complex example is useful for benefit users' understanding in getter function. Maybe we can remove this example and only leave examples of array and struct the mitigate confusion.

[haoyang9804]

I think the Complex example is useful for benefit users' understanding in getter function. Maybe we can remove this example and only leave examples of array and struct the mitigate confusion.

I have merged the struct example and the array example. As for the Complex one that combine mapping and struct, since it implies no corner case, I removed it.
As for the ABI part, I think I can submit another pr after gaining some background.