I guess I have to make use of the utility.batch call but I am not sure how to pass the different anonymous proxy TXs in the batch call. I am also not sure of the use of the variable index in the anonymous call. Maybe it is there to distinguish the different anonymous proxy transactions?
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The reason for the index in the anonymous call in pallet-proxy is exactly for the purposes of disambiguating multiple anonymous proxies in a single transaction.
It's because of the way that the proxies module deterministically generates account IDs for proxies: https://github.com/paritytech/substrate/blob/f98ef8abfc54bb7801b21be899e63f5058350e14/frame/proxy/src/lib.rs#L648-L664
pub fn anonymous_account( who: &T::AccountId, proxy_type: &T::ProxyType, index: u16, maybe_when: Option<(T::BlockNumber, u32)>, ) -> T::AccountId { let (height, ext_index) = maybe_when.unwrap_or_else(|| { ( system::Pallet::<T>::block_number(), system::Pallet::<T>::extrinsic_index().unwrap_or_default(), ) }); let entropy = (b"modlpy/proxy____", who, height, ext_index, proxy_type, index) .using_encoded(blake2_256); Decode::decode(&mut TrailingZeroInput::new(entropy.as_ref())) .expect("infinite length input; no invalid inputs for type; qed") } As you can see, it takes the block height and current extrinsic index within the block as inputs. If this isn't within a batch call, then there's no need for disambiguation. However, if multiple calls to anonymous_account occur within the same extrinsic, they need a disambiguating input to the account ID generation function.
pub fn anonymous( origin: OriginFor<T>, proxy_type: T::ProxyType, delay: T::BlockNumber, index: u16, ) -> DispatchResult { let who = ensure_signed(origin)?; let anonymous = Self::anonymous_account(&who, &proxy_type, index, None); // .. remainder omitted } This is why fn anonymous accepts an index the user can use to avoid collisions in a batch.
