Make filter initialization compile

[TheBlueMatt]

I think Box<dyn> is maybe the simplest to understand for new Rust users. We could also use Arc<dyn> or simply &dyn .

Addresses the issue noted at https://github.com/lightningdevkit/lightningdevkit.org/discussions/55#discussioncomment-1044139

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[jochasinga]

I think Option<Box<dyn Filter>> isn't allowed because it doesn't implement Deref.

https://github.com/lightningdevkit/lightningdevkit.org/discussions/55#discussioncomment-1059653

[TheBlueMatt]

The constructor takes an Option, the struct is parameterized by the thing inside the option (which must be Deref), so this should work. See https://docs.rs/lightning/0.0.99/lightning/chain/chainmonitor/struct.ChainMonitor.html#method.new

[jochasinga]

I think Option<Box<dyn Filter>> isn't allowed because it doesn't implement Deref.

#55 (reply in thread)

I think Option<Box<dyn Filter>> isn't allowed because it doesn't implement Deref.

#55 (reply in thread)

UPDATE: My confusion over ChainMonitor::new(...) accepting Option<Box<dyn Filter>> and Box<dyn Filter>. This is all good.