Quote from: Kallisteiros on July 16, 2018, 11:37:30 PM

The best practice is to generate a different bitcoin address for each visitor in the restaurant, which would result in a different QR code each time. Firstly, reusing the same address twice is discouraged. And second, trying to distinguish users by amount they sent or by correlating the time they do it is a very unstable strategy. What if the payment gets delayed? What if you have more than one checkout point/waiter with the smartphone? Generating a separate address for each check solves all problems.

If it was not for a restaurant, but, let's say, a public display with the address to send donations, and you wanted to hide the total, you could change the address each time you receive a payment there.

And finally, what you propose can fully be done only in complete hell-bent on privacy blockchains like Monero. In Monero, you can display your address publicly, a sender can see their transaction confirmed, but they can never know how much XMR went into the same address from other senders, and, by extension, how much total you have in your account.

Definitely agree. Note that although right now bitcoin is under public blockchain, the industry is promoting and concerning about the development of privacy coin. In the wechat payment system in China, our accounts can provide a new and different QR codes for new transactions. It is a good idea about generating different QR code to avoid duplicate transaction at the same time or cannot record correctly.