It's about power dynamics. You ask someone above you. You tell someone below you. You discuss with someone on the same level as you. If you're smart, you'll q

It's about power dynamics. You ask someone above you. You tell someone below you. You discuss with someone on the same level as you. If you're smart, you'll quickly spot the assholes who think they're above others - you probably shouldn't comment on their code at all, other than 'great, looks good'. If you think someone is below you, you're an asshole. If you want to discuss, you need to include the word 'because'. 'Hey, can we do X, because I/we will need it for Y?' is the way I usually go about it. By the way, discussions are best had before anyone writes code, not after. So for me, I don't do code review - if someone's bad enough that they need their code reviewed on a regular basis, I will be leaving soon anyway.