Path payment that allows you to specify how much you will send about stellar-protocol

[MonsieurNicolas]

Can you expand on scenarios - properties on Offers themselves may help and be more generic

[jedmccaleb]

I have $10 and I want to send all of it to you but you only want EUR.
Actually maybe this should just be accomplished in 2 steps. a normal order to convert the USD -> EUR and then a payment. A little gross since you have to also add/remove the trust line to EUR.

[istrau2]

@jedmccaleb I don't think that 2 step method works though (because an offer is a limit order and path payment is a market order).

To me, a path payment is mechanism for conversion between assets at market rate, a very useful function. While there are obviously scenarios where you want to specify the destination amount (like paying a merchant in their preferred asset), there are a host of scenarios where one would want to specify the source amount.

I think we should think about hard forking (or whatever the term is in stellar) to modify the protocol.

[jedmccaleb]

a limit order is a market order if you set the limit low enough. (path payment is also a limit order anyway since you put in the max to send)

The real issue is that the 2 step method isn't atomic. But this is probably solvable by allowing a payment that sends as much of an asset as it can. So then in one tx you would have 4 operations:

• add trust for EUR
• sell USD for EUR
• send as much EUR as you can to B
• remove trust for EUR

[istrau2]

@jedmccaleb
Yeah, I guess you are right about the real issue (not having the two operations be atomic).

Couple of points with your proposed solution:

1. Why solve it that way? It seems like quite a roundabout way of solving the issue (as opposed to simply allowing a path payment that specifies a source amount)?

2. Also, I think that kind of a series of operations would run into issues if the user already has a balance of EUR (then that balance would get sent as well). Additionally, it seems to me that there is no way to specify a maximum amount on the payment operation since you don't know what cumulative rate the trade will execute at ahead of time.

[jedmccaleb]

Yeah I'm open to a protocol change to add this I just want to make sure we need to first

[istrau2]

@jedmccaleb Wouldn't adding a maximum amount for a payment require a protocol change as well?

[MonsieurNicolas]

reason I was asking about offers and clarification on scenarios in the first place was that I was thinking we could create offers that cannot be taken partially for example which seems like a very useful building block.

[jonjove]

Addressed by CAP-24