Is reviewing generated code on topic ?
Scenarios:
If we were asking about any generated output other than code, the answer would be an obvious and resounding "No, you can't judge a program based on its output."
And I know that's not exactly what's being asked here, but that's essentially the intent behind the first two scenarios described in this question. In these cases, we're stuck with a user who has put the cart before the wagon. He's written an app to generate output... but he's unsure what the output should look like.
So, realistically, what should be reviewed, is a sample of what the generator might produce.
If you're writing code-generation code, you need a very concise, specific goal as for what the generated code should look like. And I'm completely fine with seeing a project created for the sake of hammering out what the output of the generated code should look like. And in this case, that it is generated code is irrelevant (and should be left out of the question).
From here, once the template for the generated code has been reviewed and hammered down, and the developer creating the code generation software is satisfied with the output, then the code generation software should be based on its code--not on the code it outputs.
In no other circumstance would we consider it acceptable to review a piece of code based on its output--why should output that happens to itself be code be any different?
I have a lexer and a parser generated by ANTLR4 in C# ..but I didn't write that code, and even if I put it up for review, and even if it does get reviewed, then what? I'm not going to modify generated code and rename all the generated methods to PascalCase because that's how C# code should look like - these changes will be lost as soon as I regenerate the code!
However the grammar file, if I had written it myself (or the parts I wrote myself), would be suitable for a code review; reviewing that grammar file requires knowledge of the generator tool (here ANTLR), so no one reviewing it is going to suggest naming my grammar rules in PascalCase (to generate C#-ish method names) because they know the tool has a Java background and will not even recognize the grammar rules if I do that.
Knowing what the generator input (like that grammar file) is supposed to be doing helps reviewers - if I say "that grammar takes VBA code for input", then reviewers can assume that as working code, the grammar effectively produces a working lexer and parser that can process VBA; asking for ways to fix issues would be off-topic - I couldn't ask how I could change my grammar to recognize commented-out code, for example.
But I could ask about the naming of the grammar rules (which is crucial here); I could ask about redundant or convoluted ways to achieve what the grammar is doing and whether/how that could be improved.
But the generated code? Reviewing it would only waste everyone's time.
What generated code are we talking about?
Are we talking about a whole game that has been generated? Good luck in making such a generator in the first place. But even if you did, I would have to say: No. I don't consider this really "your code", even if you did write the method or not. You didn't write the code.
Are we talking about a generated constructor? I use my IDE all the time to generate constructors, toString methods, equals and hashCode implementations, etc. Are such code on-topic? Absolutely. (At least I don't see any close votes on my questions...)
A question with parts of the code generated? Sure.
A question with all of the code generated? No thanks.
.Equals() implementation based on some parameters that I pass in. Why would I not be allowed to show you the resulting output and ask whether the implementation follows conventions?
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Commented
Mar 12, 2015 at 14:45
In other words, I think we can review the generated code as long as the feedback is directly going back to improving the generator (possible with first-party generators).
Generated code is not code that you have written, especially if the Generator is a 3rd-Party application/generator.
I would say, no.
If you wrote the code for the Generator then the output would be to show that the code(generator) that you wrote works. only in that instance would a question including Generated code be on topic.
The other question, is code Generated by a 3rd party generator my code?
I personally feel that if we are having to look at output to 'review' code, then we are not really 'reviewing' code, but rather determining that the code that generated the output works correctly. And in that respect, that indicates (to me) that the generator code is broken and thus it is off topic for code review.
A definition from the GNU General Public License is applicable here. In that license, the source code in the preferred form for modification must be provided along with any binaries.
That wording works very well here - so we can review Yacc source files, but not Yacc's output, and similarly for RPC stubs and and other code-generating tools. There's no point reviewing code that will not (perhaps cannot) be edited by a human.
If the code under review is itself a code generator, then it's useful to illustrate the question with sample input/output pairs, but best to be clear that is not for review (e.g. by marking as a quotation using > prefix).
Yes, it's always ontopic.
Either you write the generator yourself or you configure the generator in a way that it creates output the way you want it.
In both scenarios you have a direct influence on the resulting code and as such warrants a review. This counts for the generator code, the configuration code and the generated code.
