Multiple improvements to the decl_module! macro

[bkchr]

1. Removes weird where origin = Origin where system = System and replaces with more rusty syntax:
   where origin = Origin, system = System.
2. Makes it possible to easier implement deposit_event by either writing fn deposit_event() = default which creates the default implementation or by using fn deposit_event(my_event: MyEvent) { //myimpl } which supports any custom implementation. This fixes: Automatically impl deposit_event  #920
3. Calls are now required to be implemented directly in the decl_module! macro. This reduces boilerplate code, as now extra impl<T: Trait> Module<T> block is required.

This currently does not compile on stable, we need to wait for Thursday (23.10), where the required feature will be released as stable with rust 1.30.0.

[gavofyork]

doesn't build, needs resolving...

[bkchr]

Yeah as written in the description, this requires rust 1.30.0 that should be released today.

[chrisdcosta]

I'm not sure if this is related I think this may be causing breaking changes to custom modules (Gavin's demo?) - I'm getting compile errors error: no rules expected the token 'normalize' this error originates in a macro outside of the current crate on rust 1.30.0 with or without function code in the impl<T: Trait> Module<T>

[bkchr]

@chrisdcosta do you have more context for me? Did you tried to redo gav's demo? If yes, you now need to place your implementation directly into the decl_macro!.

So before you had something like:

decl_macro! {
    struct Module {
        fn my_call(origin, data:i32) -> Result;
    }
}

impl Module {
   fn my_call(origin, data: i32) -> Result { 
        //my impl
   }
}

Now you have to write it like:

decl_macro! {
    struct Module {
        fn my_call(origin, data: i32) -> Result { 
            //my impl
        }
    }
}

[chrisdcosta]

Yes I'd seen the changes in the SRML modules. I was building using the paired-down demo version of substrate generated by substrate-node-new but it may have been installed before your recent updates from master. Am checking this now.

[bkchr]

Okay

[chrisdcosta]

OK I've tied this error down - it's not a problem with the build - it's my use of a type definition for origin in the struct following the live demo.

In the live demo the function signature for set_payment inside the struct Module explicitly typed the first argument fn set_payment(_: T::Origin, value: T::Balance) -> Result {...}.

This causes the error - and presumably is because the changes mean that if origin is typed in the where of the struct definition it does not now need to be specified in the structs own function signatures. Is this correct?

[chrisdcosta]

Should add that it now compiles correctly like this fn set_payment(_origin, value: T::Balance) -> Result {...}