C++ says “We have try at home”

(devblogs.microsoft.com)

44 points | by ibobev 5 hours ago

4 comments

  • jasode 2 hours ago
    The submitted title is missing the salient keyword "finally" that motivates the blog post. The actual subtitle Raymond Chen wrote is: "C++ says “We have try…finally at home.”"

    It's a snowclone based on the meme, "Mom, can we get <X>? No, we have <X> at home." : https://www.google.com/search?q=%22we+have+x+at+home%22+meme

    In other words, Raymond is saying... "We already have Java feature of 'finally' at home in the C++ refrigerator and it's called 'destructor'"

    To continue the meme analogy, the kid's idea of <X> doesn't match mom's idea of <X> and disagrees that they're equivalent. E.g. "Mom, can we order pizza? No, we have leftover casserole in the fridge."

    So some kids would complain that C++ destructors RAII philosophy require creating a whole "class X{public:~X()}" which is sometimes inconvenient so it doesn't exactly equal "finally".

    • thombles 1 hour ago
      HN has some heuristics to reduce hyperbole in submissions which occasionally backfire amusingly.
      • mort96 1 hour ago
        Yeah it's a huge mistake IMO. I see it fucking up titles so frequently, and it flies in the face of the "do not editorialise titles" rule:

            [...] please use the original title, unless it is misleading or linkbait; don't editorialize.
        
        It is much worse, I think, to regularly drastically change the meaning of a title automatically until a moderator happens to notice to change it back, than to allow the occasional somewhat exaggerated original post title.

        As it stands, the HN title suggests that Raymond thinks the C++ 'try' keyword is a poor imitation of some other language's 'try'. In reality, the post is about a way to mimic Java's 'finally' in C++, which the original title clearly (if humorously) encapsulates. Raymond's words have been misrepresented here for over 4 hours at this point. I do not understand how this is an acceptable trade-off.

      • pjmlp 1 minute ago
        You have a few minutes to change the title after the submission, I do it all the time.
      • tux3 1 hour ago
        It's rare to see the mangling heuristics improve a title these days. There was a specific type of clickbait title that was overused at the time, so a rule was created. And now that the original problem has passed, we're stuck with it.
    • vidarh 44 minutes ago
      I'm curious about the actual origin now, given that a quick search shows only vague references or claim it is recent, but this meme is present in Eddie Murphys "Raw" from 1987, so it is at least that old.
  • winternewt 13 minutes ago
    Destructors are vastly superior to the finally keyword because they only require us to remember a single time to release resources (in the destructor) as opposed to every finally clause. For example, a file always closes itself when it goes out of scope instead of having to be explicitly closed by the person who opened the file. Syntax is also less cluttered with less indentation, especially when multiple objects are created that require nested try... finally blocks. Not to mention how branching and conditional initialization complicates things. You can often pair up constructors with destructors in the code so that it becomes very obvious when resource acquisition and release do not match up.
    • jchw 3 minutes ago
      Destructors and finally clauses serve different purposes IMO. Most of the languages that have finally clauses also have destructors.

      > Syntax is also less cluttered with less indentation, especially when multiple objects are created that require nested try... finally blocks.

      I think that's more of a point against try...catch/maybe exceptions as a whole, rather than the finally block. (Though I do agree with that. I dislike that aspect of exceptions, and generally prefer something closer to std::expected or Rust Result.)

  • tryfinally 1 hour ago
    I always wonder whether C++ syntax ever becomes readable when you sink more time into it, and if so - how much brain rewiring we would observe on a functional MRI.
    • sigmoid10 1 hour ago
      It does... until you switch employers. Or sometimes even just read a coworker's code. Or even your own older code. Actually no, I don't think anyone achieved full readability enlightenment. People like me just hallucinated it after doing the same things for too long.
      • Yoric 47 minutes ago
        Sadly, that is exactly my experience.
      • usrnm 1 hour ago
        And yet, somehow Lisp continues to be everyone's sweetheart, even though creating literal new DSLs for every project is one of the features of the language.
        • vkazanov 18 minutes ago
          Lisp doesnt have much syntax to speak of. All of the DSLs use the same basic structure and are easy to read.

          Cpp has A LOT A of syntax: init rules, consts, references, move, copy, templates, special cases, etc. It also includes most of C, which is small but has so many basic language design mistakes that "C puzzles" is a book.

    • deliciousturkey 38 minutes ago
      In my opinion, C++ syntax is pretty readable. Of course there are codebases that are difficult to read (heavily abstracted, templated codebases especially), but it's not really that different compared to most other languages. But this exists in most languages, even C can be as bad with use of macros.

      By far the worst in this aspect has been Scala, where every codebase seems to use a completely different dialect of the language, completely different constructs etc. There seems to have very little agreement on how the language should be used. Much, much less than C++.

    • m-schuetz 1 hour ago
      "using namespace std;" goes a long way to make C++ more readable and I don't really care about the potential issues. But yeah, due to a lack of a nice module system, this will quickly cause problems with headers that unload everything into the global namespace, like the windows API.

      I wish we had something like Javascript's "import {vector, string, unordered_map} from std;". One separate using statement per item is a bit cumbersome.

    • z0ltan 19 minutes ago
      [dead]
  • mojuba 1 hour ago
    I like how Swift solved this: there's a more universal `defer { ... }` block that's executed at the end of a given scope no matter what, and after the `return` statement is evaluated if it's a function scope. As such it has multiple uses, not just for `try ... finally`.
    • dwattttt 1 hour ago
      I was contemplating what it would look like to provide this with a macro in Rust, and of course someone has already done it. It's syntactic sugar for the destructor/RAII approach.

      https://docs.rs/defer-rs/latest/defer_rs/

    • troglo-byte 33 minutes ago

          #include <iostream>
          #define RemParens_(VA) RemParens__(VA)
          #define RemParens__(VA) RemParens___ VA
          #define RemParens___(...) __VA_ARGS__
          #define DoConcat_(A,B) DoConcat__(A,B)
          #define DoConcat__(A,B) A##B
          #define defer(BODY) struct DoConcat_(Defer,__LINE__) { ~DoConcat_(Defer,__LINE__)() { RemParens_(BODY) } } DoConcat_(_deferrer,__LINE__)
      
          int main() {
              {
                  defer(( std::cout << "Hello World" << std::endl; ));
                  std::cout << "This goes first" << std::endl;
              }
          }
      • rezonant 19 minutes ago
        Why would that be preferable to just using an RAII style scope_exit with a lambda
      • _nalply 21 minutes ago
        Your code has a bug! Why doesn't this work?

            defer(( some_code )); defer(( more_code ));
            </s>