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If there is a useful metric, then I haven't found it yet. The data on cyclomatic complexity[1] does not convince me, and in practice, the linters I've seen have

If there is a useful metric, then I haven't found it yet. The data on cyclomatic complexity[1] does not convince me, and in practice, the linters I've seen have complained about boring code like this: switch (foo) { case KIND_1: return parseObjectOfKind1(); case KIND_2: return parseObjectOfKind2(); case KIND_3: return parseObjectOfKind3(); ... case KIND_15: return parseObjectOfKind5(); case KIND_16: return parseObjectOfKind16(); } There are 16 paths and yet this code is easy to follow. There is no substitute for human judgement (code reviews). [1] https://en.wikipedia.org/wiki/Cyclomatic_complexity#Correlation_to_number_of_defects https://en.wikipedia.org/wiki/Cyclomatic_complexity#Correlat...

Waterluvian 6y ago
That's what I was thinking about when I used "ideas". To me there's one main idea in all that code: "we are returning a parsed object of a kind" Not that I'm trying to sell "ideas". I don't even know. But it's this very loose concept that floats around my mind when writing code. How many ideas are there in a stanza? Ahh too many. I should break out one of the larger ideas to happen before.
- segfaultbuserr 6y ago
  Speaking of measuring "ideas", the holy grail of complexity metric is Kolmogorov complexity - theoretically, the inherent complexity of a piece of data (including code) can be defined as the shortest possible program that generates it. For example, 20 million digits of pi or a routine that uses 20 branches to return the same object has low Kolmogorov complexity, because it's easy to write a generator for that, meanwhile a parser is more complex. But it's only a mathematical construction and is uncomputable, just like the halting problem. In real life, for some applications a good compression algorithm like LZMA is sufficient to approximate it. But I'm not sure if it's suitable for measuring computer programs - it would still have a strong correlation to the number of lines of code.
nitrogen 6y ago
It kind of encourages you to use a lookup table or polymorphism, which isn't far off from what the compiler is likely to do with that switch statement. As for correlation to number of defects, another important factor is maintainability (velocity of new features in growing programs, keeping up with infrastructure churn in mature programs). If reducing perceived complexity improves maintainability, and if measuring cyclomatic complexity despite its flaws helps reduce perceived complexity, then it's still a useful metric.
- Waterluvian 6y ago
  Feels like one of those classic, "no one tool gives you the one correct answer. They all give you data and you come to an informed conclusion having utilized one or many of them."
- gurkendoktor 6y ago
  > It kind of encourages you to use a lookup table or polymorphism And I think that is a problem. switch()ing over an enum will give you a warning about unhandled cases in some languages. But if you start building your own lookup tables, you will be just as prone to typos like mine, except with more code, and less static analysis. Yet the cyclomatic complexity drops from 16 to 1. I don't think that's a healthy incentive.
  - nitrogen 6y ago
    I think that's a fair criticism of a specific failing of a specific complexity metric. A reasonable response, especially if switch statements or pattern matches in your language are better at detecting completeness than other approaches, might be changing the metric to reward switch statements that completely cover the input range. It also makes it clear why any one metric should not be a target with no exceptions. I don't think it invalidates the concept of measuring complexity.
    - gurkendoktor 6y ago
      There are many things that the complexity calculator could take into account: the specifics of the language, the libraries that are used (which could start threads or contain hidden conditionals), the kind of project (following a spec vs. explorative programming), and so on. I think it's easy to come up with an algorithm that's better than a coin flip or counting LOC. But to be useful, the algorithm has to be on par with the judgement of the developers who check in the code and review it. Otherwise the false positives will take time away from other bug-reducing activities like code reviews and writing tests. Of course I don't have data to prove it, but I'm convinced that every complexity checker I've encountered in the last 15 years has been a (small) net negative for the project. Maybe machine learning will improve the situation.
colonelpopcorn 6y ago
Except it's not easy to follow. Why does kind 15 return a parsed object of kind 5? That's not counting the complexity of each function called, either.
- johncolanduoni 6y ago
  I think they were using the numbers as stand-ins for what would be in reality names be descriptive names (foo, bar, etc.).
- gurkendoktor 6y ago
  Ouch, sorry for the typo. But I'll double down on this: The fact that the typo is so obvious underlines that the structure is easy to review :)
wvenable 6y ago
> case KIND_15: return parseObjectOfKind5(); I don't like this type of code for exactly this reason.
- Twisol 6y ago
  The association between the two has to be written somewhere. Can you provide an alternative approach that isn't vulnerable to typos?
  - Jtsummers 6y ago
    Their point seems to be in the mismatch of names. Imagine seeing this sequence, with names instead of numbers: switch(HTTP_METHOD) { case PUT: processPut(...); case POST: processPost(...); case GET: processDelete(...); // wtf case DELETE: processGet(...); // mate? } To the reader that appears to be an error even if it is precisely the thing you want to happen.
  - Leherenn 6y ago
    Depends on your language, but you could use the type system instead; e.g. the function is chosen by the compiler based on the type of the value. In more dynamic languages, you could probably use introspection. Lastly, this does not alleviate the association issue, but I prefer the alternative of declaring the associations in an array/map somewhere, and using map[enum_value]() instead of the switch.
    - slaymaker1907 6y ago
      In a lot of ways, I think the map solution is actually worse. There isn't an easy way to figure out what code is used for a given enum value with the map alone. The searchability depends on how the map is initialized. Not to mention a map will always introduce null or option types that you have to handle. A map can be a good solution though, particularly if it's something like mapping enum values to strings that is constructed via EnumClass.values().map... or something so that you know the map is a total function.
oftenwrong 6y ago
This is one of the benefits of Cognitive Complexity: https://www.sonarsource.com/docs/CognitiveComplexity.pdf https://www.sonarsource.com/docs/CognitiveComplexity.pdf >Switches >A `switch` and all its cases combined incurs a single structural increment. >Under Cyclomatic Complexity, a switch is treated as an analog to an `if-else if` chain. That is, each `case` in the `switch` causes an increment because it causes a branch in the mathematical model of the control flow. >But from a maintainer’s point of view, a switch - which compares a single variable to an explicitly named set of literal values - is much easier to understand than an `if-else if` chain because the latter may make any number of comparisons, using any number of variables and values. >In short, an `if-else if` chain must be read carefully, while a `switch` can often be taken in at a glance.
- slaymaker1907 6y ago
  Great paper! I particularly liked how they treat boolean expressions. It kind of has a mathematical justification as well since a series of only && or || is trivial for a SAT solver. I disagree with them on assuming method calls being free in terms of complexity. Too much abstraction makes it difficult to follow. I've heard of this being called lasagna code since it has tons of layers (unnecessary layers). Maybe the complexity introduced by overabstraction requires other tools to analyze? It's tricky to look at it via cylcomatic complexity or cognitive complexity since it is non-local by nature.

Waterluvian 6y ago

That's what I was thinking about when I used "ideas". To me there's one main idea in all that code: "we are returning a parsed object of a kind" Not that I'm trying to sell "ideas". I don't even know. But it's this very loose concept that floats around my mind when writing code. How many ideas are there in a stanza? Ahh too many. I should break out one of the larger ideas to happen before.

segfaultbuserr 6y ago
Speaking of measuring "ideas", the holy grail of complexity metric is Kolmogorov complexity - theoretically, the inherent complexity of a piece of data (including code) can be defined as the shortest possible program that generates it. For example, 20 million digits of pi or a routine that uses 20 branches to return the same object has low Kolmogorov complexity, because it's easy to write a generator for that, meanwhile a parser is more complex. But it's only a mathematical construction and is uncomputable, just like the halting problem. In real life, for some applications a good compression algorithm like LZMA is sufficient to approximate it. But I'm not sure if it's suitable for measuring computer programs - it would still have a strong correlation to the number of lines of code.

nitrogen 6y ago

It kind of encourages you to use a lookup table or polymorphism, which isn't far off from what the compiler is likely to do with that switch statement. As for correlation to number of defects, another important factor is maintainability (velocity of new features in growing programs, keeping up with infrastructure churn in mature programs). If reducing perceived complexity improves maintainability, and if measuring cyclomatic complexity despite its flaws helps reduce perceived complexity, then it's still a useful metric.

Waterluvian 6y ago
Feels like one of those classic, "no one tool gives you the one correct answer. They all give you data and you come to an informed conclusion having utilized one or many of them."
gurkendoktor 6y ago
> It kind of encourages you to use a lookup table or polymorphism And I think that is a problem. switch()ing over an enum will give you a warning about unhandled cases in some languages. But if you start building your own lookup tables, you will be just as prone to typos like mine, except with more code, and less static analysis. Yet the cyclomatic complexity drops from 16 to 1. I don't think that's a healthy incentive.
- nitrogen 6y ago
  I think that's a fair criticism of a specific failing of a specific complexity metric. A reasonable response, especially if switch statements or pattern matches in your language are better at detecting completeness than other approaches, might be changing the metric to reward switch statements that completely cover the input range. It also makes it clear why any one metric should not be a target with no exceptions. I don't think it invalidates the concept of measuring complexity.
  - gurkendoktor 6y ago
    There are many things that the complexity calculator could take into account: the specifics of the language, the libraries that are used (which could start threads or contain hidden conditionals), the kind of project (following a spec vs. explorative programming), and so on. I think it's easy to come up with an algorithm that's better than a coin flip or counting LOC. But to be useful, the algorithm has to be on par with the judgement of the developers who check in the code and review it. Otherwise the false positives will take time away from other bug-reducing activities like code reviews and writing tests. Of course I don't have data to prove it, but I'm convinced that every complexity checker I've encountered in the last 15 years has been a (small) net negative for the project. Maybe machine learning will improve the situation.

colonelpopcorn 6y ago

Except it's not easy to follow. Why does kind 15 return a parsed object of kind 5? That's not counting the complexity of each function called, either.

johncolanduoni 6y ago
I think they were using the numbers as stand-ins for what would be in reality names be descriptive names (foo, bar, etc.).
gurkendoktor 6y ago
Ouch, sorry for the typo. But I'll double down on this: The fact that the typo is so obvious underlines that the structure is easy to review :)

wvenable 6y ago

> case KIND_15: return parseObjectOfKind5(); I don't like this type of code for exactly this reason.

Twisol 6y ago
The association between the two has to be written somewhere. Can you provide an alternative approach that isn't vulnerable to typos?
- Jtsummers 6y ago
  Their point seems to be in the mismatch of names. Imagine seeing this sequence, with names instead of numbers: switch(HTTP_METHOD) { case PUT: processPut(...); case POST: processPost(...); case GET: processDelete(...); // wtf case DELETE: processGet(...); // mate? } To the reader that appears to be an error even if it is precisely the thing you want to happen.
- Leherenn 6y ago
  Depends on your language, but you could use the type system instead; e.g. the function is chosen by the compiler based on the type of the value. In more dynamic languages, you could probably use introspection. Lastly, this does not alleviate the association issue, but I prefer the alternative of declaring the associations in an array/map somewhere, and using map[enum_value]() instead of the switch.
  - slaymaker1907 6y ago
    In a lot of ways, I think the map solution is actually worse. There isn't an easy way to figure out what code is used for a given enum value with the map alone. The searchability depends on how the map is initialized. Not to mention a map will always introduce null or option types that you have to handle. A map can be a good solution though, particularly if it's something like mapping enum values to strings that is constructed via EnumClass.values().map... or something so that you know the map is a total function.

oftenwrong 6y ago

This is one of the benefits of Cognitive Complexity: https://www.sonarsource.com/docs/CognitiveComplexity.pdf https://www.sonarsource.com/docs/CognitiveComplexity.pdf >Switches >A `switch` and all its cases combined incurs a single structural increment. >Under Cyclomatic Complexity, a switch is treated as an analog to an `if-else if` chain. That is, each `case` in the `switch` causes an increment because it causes a branch in the mathematical model of the control flow. >But from a maintainer’s point of view, a switch - which compares a single variable to an explicitly named set of literal values - is much easier to understand than an `if-else if` chain because the latter may make any number of comparisons, using any number of variables and values. >In short, an `if-else if` chain must be read carefully, while a `switch` can often be taken in at a glance.

slaymaker1907 6y ago
Great paper! I particularly liked how they treat boolean expressions. It kind of has a mathematical justification as well since a series of only && or || is trivial for a SAT solver. I disagree with them on assuming method calls being free in terms of complexity. Too much abstraction makes it difficult to follow. I've heard of this being called lasagna code since it has tons of layers (unnecessary layers). Maybe the complexity introduced by overabstraction requires other tools to analyze? It's tricky to look at it via cylcomatic complexity or cognitive complexity since it is non-local by nature.