This write-up is partly inspired by a recent post by Vlad Mihalcea on LinkedIn about the recently introduced text blocks in Java. More about them can be read here.
Now, that’s a nice feature. I’ve used it in Scala several years ago, and other languages also have it, so it seems like a no-brainer to introduce it in Java.
But, syntactic sugar (please don’t argue whether that’s precisely syntactic sugar or not) can be problematic and lead to “syntactic diabetes”. It has two possible issues.
The less important one is consistency – if you can do one thing in multiple, equally valid ways, that introduces inconsistency in the code and pointless arguments of “the right way to do things”. In this context – for 2-line strings do you use a text block or not? Should you do multi-line formatting for simple strings or not? Should you configure checkstyle rules to reject one or the other option and in what circumstances?
The second, and bigger problem, is code readability. I know it sounds counter-intuitive, but bear with me. The example that Vlad gave illustrates that – do you want to have a 20-line SQL query in your Java code? I’d say no – you’d better extract that to a separate file, and using some form of templating, populate the right values. This is certainly readable when you browse the code:
String query = QueryUtils.loadQuery("age-query.sql", timestamp, diff, other); // or String query = QueryUtils.loadQuery("age-query.sql", Arrays.asList("param1Name", "param2Name"), Arrays.asList(param1Value, param2Value);
Queries can be placed in /src/main/resources and loaded as templates (and cached) by the
QueryUtils. And because of the previous lack of text blocks, you would not prefer ugly string concatenated queries inside your code.
But now, with this feature, you are tempted to do that, because, well, it looks good. Same goes for Elasticsearch queries, for JSON templates and whatnot. With this “sugar” you have more incentive to just put them in the code, where they, arguably, make the code less readable. If you really have to debug the query, as opposed to assuming its semantics by its name and relying on a proper implementation, you can easily go to
age-query.sql and work with it. Just like when you extract a private method with some implementation details so that it makes the calling method more readable and easy to follow.
Both problems have manifested themselves in my Scala experience, which I’ve summed up in my talk “Scala – the good, the bad and the very ugly” (only slides available). Scala allows you to express things nicely and in multiple ways, which leads to inconsistencies and horrible code readability in some cases.
Counter intuitively, sometimes the syntactic improvements may be worse for code readability. Because they introduce complexity and because they make it easier to do the wrong thing.
That’s not a universal complaint, and certainly syntactic sugar is needed – you don’t have to write
List<String> list = new ArrayList<String>() if you can use the diamond operator. But each such feature should be well thought not just for how easy it makes to write the code, but also how easy it is to read it, and more importantly - what type of code it incentivizes.
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