dev: make EVM an implicit argument of EVM-modifying functions

[enitrat]

func charge_gas{range_check_ptr}(self: model.EVM*, amount: felt) -> model.EVM* {

takes the EVM as explicit parameters and returns a new instance.
It could be refactored to

func charge_gas{range_check_ptr, evm: model.EVM*}(amount: felt) {

[joseSalazar4]

Hey there! Could I take this one? I believe the idea is to modify the attributes of the EVM received so we don't create a new instance with almost all the parms being the same on the second instance creation, correct?

[enitrat]

@ClementWalter should we go forward with this?

[ClementWalter]

@joseSalazar4 it wouldn't save any steps actually, it's just to (possibly) increase readability. Tbh I'm not 100% sure that it'd be much better though, because the explicit f(evm) -> evm shows well that the evm is updated, as opposed to f().

If you want to give it a try, please, but be aware of the fact that upon PR, when actually seing it, we may decide to close instead of merge

[ClementWalter]

(to be more precise, in Cairo Zero, using an implicit arg is exactly the same as defining the same arg (same name and type) as input and output

[joseSalazar4]

Your comment makes a lot of sense, this is better being explicit, agreed.