4 ms·

There's a JVM language out there that initially allowed try-statements without catch or finally clauses, e.g try{ //for a short time only to decide

• ddlatham 15y ago
  What benefits does an empty try block give you? You can always use braces to separate a block without try at all.
  • superkarn 15y ago
    You can use it to suppress exceptions.
  • vorg 15y ago
    > What benefits does an empty try block give you? An empty try block allows us to repeat variable declarations with the same name in a long stretch of scripty-style code. > You can always use braces to separate a block without try at all. You can use braces in Java, but not in that language I'm talking about: it'll throw an error saying "Ambiguous expression could be a parameterless closure expression, an isolated open code block, or it may continue a previous statement; solution: Add an explicit parameter list, e.g. {it -> ...}, or force it to be treated as an open block by giving it a label, e.g. L:{...}, and also either remove the previous newline, or add an explicit semicolon ';'". The standalone-try looked far more elegant than: dudlabel:{ //do something } Better for that despot to re-enable standalone try-statements in Groovy than petitioning the Java 8 designers that thin arrows look better than industry-standard thick arrows.
    • mattgreenrocks 15y ago
      > An empty try block allows us to repeat variable declarations with the same name in a long stretch of scripty-style code. Either I'm missing something here, or this is really as bad as it sounds. I understand you want nested scopes that end before the method's scope ends, but cannot for the life of me think of a defensible code example. Why not just make them into methods?
      • ajuc 15y ago
        In C++ block is often a way to ensure automatic variable destruction. This is important, because in C++ often there is important stuff going on in destructor. For example in RAII idiom. Example: ... ... { //critical section QMutexLocker locksInConstructorAndUnlocksInDestructor(&mutex); a = doStuff(a,b,c); b = doOtherStuff(a,b,c); c = andAnother(a,b,c); } .. .. It would be overkill to make this block a function, especially when code in critical section changes many variables.
        • scott_s 15y ago
          This is an accepted idiom in C++, but I don't think it makes much sense in Java, since there are no destructors.
      • strictfp 15y ago
        And why not pick java simpler nested scope syntax '{ //doit }'?
      • vorg 15y ago
        I did say scripty code. My typical scripting session from scratch starts with opening a simple editor and starting to type in code. The structure is loose, perhaps it's testing something I've written in another file in a statically-typed language. As the code evolves, I slowly give it more structure by reworking it. At some stage I MIGHT put some code into methods. But before that stage, nested scopes are useful because I'm far less likely to pass the wrongly-named variable into a function when I'm cutting and pasting code. An example coding snippet... def out= new File("blah") try{ def testdata= "abcdefg" def result= SomethingToTest(testdata, out) assert result == result.getSth() } try{ def testdata= "hijk" try{ def result= SomethingToTest(testdata, out) assert result == result.getSth() } try{ def result= SomethingToTest(testdata) assert result == result.getSth() } } If I use testdata1, testdata2, result1, result2, etc, I might forget to rename a variable after cutting and pasting, and think a test works when it doesn't.
• jmillikin 15y ago
  But one of its despots, five years after the language was first released, changed the syntax to make a catch or finally clause compulsory, e.g Are you the person who believes the Groovy developers are personally working to invalidate your web tutorials so they can discredit your fork of the language? Lest HN think I'm being ungenerous, please read http://groovy.codeplex.com/wikipage?title=Blog01 http://groovy.codeplex.com/wikipage?title=Blog01 , which features similar language regarding "despots". Of course, Groovy also differentiates itself from Guava by having a dedicated language syntax, which is no doubt why the cartel don't want to standardize it. If it was standardized, they couldn't make some random blogger's sample code stop working by suddenly requiring all try-statements to have an empty finally clause.
  • vorg 15y ago
    > the Groovy developers Probably just one of them.
• yock 15y ago
  Perhaps you can educate me on your better reasoning, but the only purpose I can see for an empty try block is to limit the scope of variables in a method. Quite frankly, if you find yourself in need of artificially limiting the scope of variables in a method, you've probably done too much in the method and need to refactor. Try block are for just that, trying something you know ahead of time might fail. There's no point in using the try paradigm if you don't also intend to handle the expected failure.
  • felipemnoa 15y ago
    If you just want to limit the scope you can just enclose your code in braces without the try. A try without the catch or finally is meaningless.