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Help me sort out the meaning of “{}” as a constructor argument

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Re: Help me sort out the meaning of “{}” as a constructor argument

#81

Post by CJefferson »

gpderetta wrote: post #2

The answer to the problem can be found in the comments, but not in a single place: X {{}}; will: for T = DefCtor call the initializer_list constructor with a single default constructed element. The outer brakets are for the initalizer list and the inner ones are for the DefCtor constructor. The brackets for T constructor itself are allowed to be elided. for T = NoDefCtor, the previous overload resolution is not valid…

This issue is what stopped me contributing to the C++ standard. We knew brace initialisation was broken before C++11 came out, even std::vector was a mess.

Re: Help me sort out the meaning of “{}” as a constructor argument

#82

Post by marcosdumay »

pklausler wrote: post #20
johan_larson wrote: post #14

Earlier quoted context omitted.

Any sense of where the C++ refugees are heading? Rust? Go?

Haskell, at least in my case.

Haskell has syntax that is as problematic as this one, and a huge number of extension combinations that nobody can be sure not to be problematic.

I'm running into it as much as I can too, but it does look like a language we should replace with something simpler once we get an specification that works.

Re: Help me sort out the meaning of “{}” as a constructor argument

#83

Post by clappski »

sqeaky wrote: post #75
firethief wrote: post #63

Earlier quoted context omitted.

Those languages all have heavy runtime environments; if a segfault occurs it's an interpreter bug. Whether the mistakes you can make are a result of "undefined behavior" is a different question whether from the consequences of a mistake are an abrupt termination, or an abrupt termination with a helpful error message.

This is how it works in Ruby. In the CRuby/MRI interpretter when a segfault happens it calls the #to_s method on the current execution context, to get the some memory address and technical details. Ruby happens to be flexible enough that you can override that method. Then you can call whatever you want and you have effectly "recovered" from a segfault. The parser is totally in an inconsistent state and could crash at…

You can do the same thing in C++, either by intercepting signals on Linux, or setting up a structured exception handler on Windows. It's useful when you either A) want to attempt a recovery or B) have a complex tear down.

Re: Help me sort out the meaning of “{}” as a constructor argument

#84

Post by nommm-nommm »

blub wrote: post #79
nommm-nommm wrote: post #56

Earlier quoted context omitted.

Java is over two decades old and one of the most widely used languages in the world. It has absolutely stood the test of time. While it does has its pain points its nowhere near as terrible as C++ and (in my opinion) is improving with new versions, and honestly, I think its a joy to program in though that might not be a "cool" thing to say. Whereas C++ is a chore to program in. That's my opinion, maybe I'm just too u…

Well, there's not a lot of room for problems to crop up when all one can do is define classes :) Still, here's a few for you: the design of Cloneable is considered to be a mistake, as are exception specifications. These have real negative consequences. File IO was laughably bad and completely unintuitive needing several classes for the simplest of tasks (perhaps this was fixed more recently, but funny you should ment…

Like I said, Java has its pain points but Java's pain points are both being drastically improved on with time (java.time anyone?) and was never as bad (in my opinion) as C++. My main point is that Java has stood the test of time without becoming as bad as C++.

I'm not impressed by "classes, methods, interfaces in abundance, class hierarchies and factories." I find Java a joy to program in because I can just Get Shit Done™ and things do what I expect them to do.

In my old age I just want to get shit done, challenging myself is no longer very appealing. That's a personal preference though. There was a time that wasn't the case.

Obviously managed code is not for every application but its good enough for most. I am eternally grateful for C++ programmers for the applications where C++ (or other lower level languages) are needed because I wouldn't want to be doing that. I think C++ programmers, as a group, are so used to C++ idiosyncrasies that they don't see them as idiosyncrasies. That goes for any group though.

For what its worth my first language was C++ but C++ always "astonished" me.

(I've never had a problem with boxing and unboxing. Java has had autoboxing for a really long time so those days of manual boxing/unboxing are ancient history)

Re: Help me sort out the meaning of “{}” as a constructor argument

#85

Post by bitL »

astral303 wrote: post #77
edblarney wrote: post #53

Earlier quoted context omitted.

I think this comment is fair, but could be misinterpreted. Scala allows you to do the same thing in many different ways, and with operator overloading ... the approach you chose to coding defines almost a 'custom syntax' for a project. Which makes it very hard to read sometimes - you have to infer the 'style' before you can get too far. To be fair - that's a different kind of 'inconvenience' than C++ from C - but the…

Exactly, the "custom syntax" is the problem. The problem is that Scala seems to attract the same type of thinking as C++, where there is a culture that rewards obscure, bizarre syntax. I mean, why is it an exclamation mark to send messages to actors in Akka? I need to write code to get things done. I want to spend minimal time figuring out bizarre operator-overloaded library syntax.

Fun like this:

http://www.flotsam.nl/dispatch-periodic-table.html

When I was a teenager, it was fun to do that in C++ until I realized everybody thought it was fun but their version of fun wasn't compatible with my version of fun.

Re: Help me sort out the meaning of “{}” as a constructor argument

#86

Post by munificent »

nommm-nommm wrote: post #56
munificent wrote: post #33

Earlier quoted context omitted.

> I've since moved on to languages that weren't full of problems like this I think you mean aren't full of those problems yet . :) There's a lot of nasty corners in C++ but almost all of them are because it effectively has 40 years of wild success. (I say 40 because C++ inherits C's baggage and success.) It's totally reasonable to pick a younger language with fewer warts. Become an expert in it! Be productive! Ship l…

Java is over two decades old and one of the most widely used languages in the world. It has absolutely stood the test of time. While it does has its pain points its nowhere near as terrible as C++ and (in my opinion) is improving with new versions, and honestly, I think its a joy to program in though that might not be a "cool" thing to say. Whereas C++ is a chore to program in. That's my opinion, maybe I'm just too u…

> Java is over two decades old and one of the most widely used languages in the world.

Half the age of C++ (and it's ancestor C which is it largely compatible with).

> It has absolutely stood the test of time.

Sure, it's held up really well. It takes advantage of the fact that baking in GC, memory safety, and platform independence sweeps a lot of C++'s nastiness under the rug. Of course, those choices are also what generally makes Java unsuitable for many of the things you can do in C++.

Even so, Java has certainly acquired it's share of cruft. Primitives, type erasure, checked exceptions, Uri.equals() hitting the network (!), nested classes, covariant arrays, arrays and lists being different and arrays getting all the nice syntax, etc.

Re: Help me sort out the meaning of “{}” as a constructor argument

#87

Post by nommm-nommm »

munificent wrote: post #86
nommm-nommm wrote: post #56

Earlier quoted context omitted.

Java is over two decades old and one of the most widely used languages in the world. It has absolutely stood the test of time. While it does has its pain points its nowhere near as terrible as C++ and (in my opinion) is improving with new versions, and honestly, I think its a joy to program in though that might not be a "cool" thing to say. Whereas C++ is a chore to program in. That's my opinion, maybe I'm just too u…

> Java is over two decades old and one of the most widely used languages in the world. Half the age of C++ (and it's ancestor C which is it largely compatible with). > It has absolutely stood the test of time. Sure, it's held up really well. It takes advantage of the fact that baking in GC, memory safety, and platform independence sweeps a lot of C++'s nastiness under the rug. Of course, those choices are also what g…

Agreed but in my opinion the cruft in Java is not nearly as bad as the cruft in C++. That's a personal opinion though, I'm mostly a Java programmer in my day job so that may cloud my perception of the language because I'm so used to it. I've never fought with Java like I have with C++.

Re: Help me sort out the meaning of “{}” as a constructor argument

#88

Post by seanwilson »

ksk wrote: post #74
seanwilson wrote: post #60

Earlier quoted context omitted.

My comment started with "C++ FAQs are full of massively complex conundrums like this for problems you just don't get in other languages" so I was making a general comment prompted by the article. > C++ is meant for low level system programming, when performance or size are constraints on the problem you're trying to solve. The problem domain itself entails a certain amount of care. Agree with this but my view is you…

IMO, Code golf is an excellent metric. Only someone who masters a language and knows its weird edge cases and obscure syntax can make sense of the answers, or attempt to present an answer themselves. If writing code with minimal bugs is your goal, then you don't need to master the language at all. So, I don't even know what we're arguing about. Looks like we agree on most things. So lemme ask you, can you name books…

> IMO, Code golf is an excellent metric. Only someone who masters a language and knows its weird edge cases and obscure syntax can make sense of the answers, or attempt to present an answer themselves.

To me, mastering a language is knowing how to use it in a way to solve a problem in the fastest development time with minimal bugs and maintainable code which does not match up with code golf. C++ gives you lots of ways to introduce weird bugs which isn't something code golf demonstrates.

> So lemme ask you, can you name books (or courses) that teach C++, and devote a significant chunk (or any) of the material to cover such arcane syntax topics?

The C++ Programming Language book and Effective Modern C++ are good and they're full of "don't do this or something bad will happen!" parts. I'm not really concerned about a few arcane syntax problems but I am concerned that C++ has a lot of undefined behaviour that lets you shoot yourself in the foot in a way that other languages avoid.

Re: Help me sort out the meaning of “{}” as a constructor argument

#89

Post by edblarney »

astral303 wrote: post #77
edblarney wrote: post #53

Earlier quoted context omitted.

I think this comment is fair, but could be misinterpreted. Scala allows you to do the same thing in many different ways, and with operator overloading ... the approach you chose to coding defines almost a 'custom syntax' for a project. Which makes it very hard to read sometimes - you have to infer the 'style' before you can get too far. To be fair - that's a different kind of 'inconvenience' than C++ from C - but the…

Exactly, the "custom syntax" is the problem. The problem is that Scala seems to attract the same type of thinking as C++, where there is a culture that rewards obscure, bizarre syntax. I mean, why is it an exclamation mark to send messages to actors in Akka? I need to write code to get things done. I want to spend minimal time figuring out bizarre operator-overloaded library syntax.

"I need to write code to get things done. "

Yes. But their cultures are a little different.

C++ I think is 1/2 academic, 1/2 Engineering - with a lot of voices, and a lot of anachronistic 'grey beards' arguing over stuff. Even for Java, James Gosling said 'Sun less less a company than it is a debating society'.

Scala is almost purely academic - but driven by a single person / small team. Scala was not designed to solve an Engineering problem, thus it seems a little 'intellectually masturbatory' (pardon the term).

Scala is way to hard to learn - partly because it's a 'new paradigm' but partly for the reasons aforementioned. So it's only going to make it's way into production for specific entities.

Scala may have a 'big future' if tutorials, training and approaches settle down on commonly accepted standards and practices.

Re: Help me sort out the meaning of “{}” as a constructor argument

#90

Post by pjmlp »

johan_larson wrote: post #73
bitL wrote: post #44

Earlier quoted context omitted.

The main advantage of C was that it allowed you to type stuff super fast comparing with Pascal ( {} instead of Begin .. End etc.) and had some very handy shortcuts for often used operations like ()?:, ++, --, += etc. Less verbose language, less need to type syntactic structures. You could basically keep the flow of what is in your mind with the progress on your keyboard and forget about typing it; you were simply ass…

I'd say the two more important advantages were a) the bare-metal view C gave you, down to individual bytes, which was important for systems-level programming, and b) the lack of overhead from things like bounds checking and garbage collection, which was useful on the butt-slow machines in the 70s and 80s.

Lots of languages allowed for a) and b), including the ones I mentioned, C wasn't neither the only one nor the first one.
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