Batch execution of submessages

[hussein-aitlahcen]

Hi,

I found that to batch a sequence of messages atomically from a contract, I had to reintroduce the following pattern:

enum MyContractMsg {
 Batch { messages: Vec<CosmosMsg> }
}


// In your handler
match msg {
   MyContractMsg::Batch { messages } if sender == self_addr =>  Response::new().add_messages(messages)
   ...
}

// Somewhere
Response::new().add_message(SubMsg::reply_on_error(REPLY_ID, wasm_execute(self_address, MyContractMsg::Batch { messages }))

The idea here is to execute N messages and get a single reply if any of them is failing (and also revert any state change made by a message in this sequence). In this case, we re-dispatch a contract message with the sequence and execute them from there, the top level reply_on_error is then executed when the previously mentioned case happen (any message error, everything is reverted). Is there a more idiomatic way to do that? If not, maybe it would be interesting to change SubMsg to accept a list of CosmosMsg? Or perhaps introduce a CosmosMsg::Batch { messages: Vec<CosmosMsg> } variant with a feature flag?

[chipshort]

That looks like a nice solution to me.
I don't think we need add an additional message for something that can be achieved this nicely in contract code.