FRAME: Introduce shelve/restore to nonfungible/nonfungibles

[gavofyork]

fungible API has deactivate and reactivate functions, which is useful for making teleport usages a bit safer. Similar functions should be introduced to the nonfungible and nonfungibles API and in a companion PR utilised during teleports.

[ruseinov]

I assume this is actionable, will take this on.

[ruseinov]

Not that I think about it - it would be nice to understand how this should work. I'm currently investigating the code to figure out what would be a good approach to this.
Once I have more overview - will likely ask more questions.

[ruseinov]

@jsidorenko I guess it's easier to ask you since you've touched this a lot.

I assume that this has to affect can_transfer. So basically in concrete implementations we'd have some sort of flag that's going to be set on shelve and restore and checked in can_transfer.

From what I have seen there are only 3 pallets currently using any of these traits (v1 and v2): nis, uniques and nft.

Please let me know if my assumptions are correct.

[jsidorenko]

For nfts fractionalization pallet we've added a new trait called LockableNonfungible that has two methods: lock and unlock. You can see the code here.
Then, on a runtime level, you can provide the custom implementation as shown here in addition to the Locker implementation that allows to check whether the nft is locked or not.

[ruseinov]

@gavofyork I wonder what the vision is for these methods.
For example, in case of fungible(s) API activate and deactivate methods are in the Transfer trait that has to be implemented by the pallet.

In case of this PR locking functionality is done by simply passing the NftLocker to the pallet and calling it's methods directly.

As far as I understand the idea here is to have those shelve/restore methods call the underlying locker (or whatever) implementation, exposing this API to whoever needs to use from outside the pallet itself.

[jsidorenko]

Solved in the NFT fractionalization PR; feel free to close this issue if happy with the solution: https://github.com/paritytech/substrate/pull/12565/files#diff-6eb7941669d2217ef2902ce147d26330e444322ef640e990be2929565ddd1f34