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| ▲ | 9rx 19 hours ago | parent [-] | | > I'm saying that this tenet is misleading. Doesn't that go without saying? There is no tenet that isn't misleading when presented to a general audience. Fair that if you come from a position where you understand the full context and nuance under which the tenet was built then you should be able to free yourself from being mislead, but, of course, this time is no exception. > If several packages consume the same interface, then you it's not reasonable to define the interface at the consumer because you'd just have to copypaste it. Where several packages find interface commonality, there is no doubt a set of "primary" functions that roll up shared functionality around that interface. The package of shared functions is understood to be the consumer under that scenario. Where several packages stumbled upon the same interface without any shared functionality, copy/pasting is warranted. In this case, while the interfaces may look the same, they do not carry the same intent and that needs to be communicated. Another oft-misunderstood tenet, do not repeat yourself, does not imply avoid repetitive code. | | |
| ▲ | the_gipsy 10 hours ago | parent [-] | | I don't quite see when a package is "understood to be the consumer" of... itself? We're talking about other packages importing an interface. I can give you a concrete example. I have a "storage" package, that exports multiple storage implementations/backends. Files, in-memory, S3, zip... Some other packages pick one of the implementations to instantiate, depending on the use case (this is NOT a case of mocking for testing or anything like that). Most other packages work with a "storage" interface, as they're only concerned with reading/writing to "storage". So the storage package, or in any case some package, has to export the interface. Otherwise, every consuming package would have to copypaste that interface, which is NOT warranted. | | |
| ▲ | 9rx 8 hours ago | parent [-] | | Actual code is always better, but based on the description it seems a bit strange that there would be a single package that exports multiple implementations. Presumably each distinct implementation should be its own package. None of these packages would export the interface. An additional package would export the interface and provide the common functionality around that interface. Those common functions would be considered the consumer. In fact, the standard library offers an example of exactly this: io/fs. | | |
| ▲ | the_gipsy 5 hours ago | parent [-] | | No, I cannot agree that this would be called the consumer. Yes, you have technically moved the interface type away from the implementation, but just for the sake of it, without any other upsides. The consumer is still the package that is using and importing this interface type, just from another package now. | | |
| ▲ | 9rx 2 hours ago | parent [-] | | That is the beauty of engineering: There is no universal truth, just different tradeoffs. Meaning that you don't need to agree, nor should you even seek agreement. You can and should forge your own path if different tradeoffs are warranted for your unique needs. But, this is the "idiomatic" approach. The upside is consistency for future readers. Code is for humans to read, after all. Most codebases follow this pattern, so it will be familiar when the next person encounters it. If you have a reason to do things differently, go for it. Nobody knows your problem better than you, so you cannot listen to others anyway. I am quite curious about what you see in the different tradeoffs you are accepting, though! What has you weighing them in favour? | | |
| ▲ | the_gipsy 16 minutes ago | parent [-] | | Sorry but I haven't really seen this pattern anywhere, care to give some examples? All libraries that I recall ever using always export a single package, including interfaces. I just took a look, and even io exports a bunch of structs along the interfaces they implement. And `error` is like a basic type of the runtime. |
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