The author said that most comments in code are duplication, not all. And that is true in the average case. Most code comments explain what the code is doing and how it does it, and so need to be updated when either of that changes. Then they get out of date, etc.
Typically, comments can just be merged into the code directly by extracting well named methods, and using better names for variables.
Good comments tend to not be redundant, they tend to tell you "why" information and be written at the level of intent rather than at the level of implementation. And thus they don't need to be continually updated when the implementation changes.
> Good comments tend to not be redundant, they tend to tell you "why" information and be written at the level of intent rather than at the level of implementation. And thus they don't need to be continually updated when the implementation changes.
This. The exception being when things have to get messy for reasons of performance or other non-obvious constraints- at which point, the comments should document why it's messy, but may also provide some guidance around the messy code.
While I can't disagree with your statement, that's not what I got as the focus of his comment. The part about code duplication is the last sentence of the comment. Before that he does state that it would be better to write precise readable code, which no one disputes (I hope), but I don't see that as a reason to discount proper comments.
I have written comments as he described where they practically duplicate the code they are describing. But when I do that it's because I'm working with multidimensional arrays and I use comments to remind me what section of what array inside what array I'm currently working on. If I change the structure of the array and don't update the comments then that's my fault.
I was reacting more to the first sentence, where he said that "poor, incorrect, outdated, misleading comments" must be the most annoying aspect of comments. I believe he is right in this regard, but this where I feel he is blaming the tool for someone misusing it.
Typically, comments can just be merged into the code directly by extracting well named methods, and using better names for variables.
Good comments tend to not be redundant, they tend to tell you "why" information and be written at the level of intent rather than at the level of implementation. And thus they don't need to be continually updated when the implementation changes.