I am scared by what C++ people think is fun.
Fun with C++26 reflection: Keyword Arguments
21–30 of 147 posts
Re: Fun with C++26 reflection: Keyword Arguments
#22Earlier quoted context omitted.
at that point why not just pass in a struct as your argument
I suppose it depends on your application. I worked in embedded devices where stack was limited and the compiler was .... less than reliable about how it would manage passing a large struct to your function, which is why I mentioned passing in a pointer instead
yes a pointer to struct would be acceptable as well
Re: Fun with C++26 reflection: Keyword Arguments
#23I just don't understand why some people are so fascinated by this. Can you all admit that this is not at all practical? I swear C++ folks like it for the sake of it. No other engineer do this. Only antiques people or whatever. Can you imagine an engineer that is adamant on using his mystifying bespoke tool instead of just using a ruler. "But what if I have to measure it in the 4th dimension!?". I was expecting someth…
Personally, I write the simplest subset of C++ I possibly can at all times. Loops, variables, classes and the STL library when useful. The more advanced features you use, the easier it is to make subtle mistakes, confuse someone who hasn't seen that feature before, or just make everyone working on the software wary of ever touching it.
I do the same thing. C++’s feature is incredibly broad, and sprinkling in just a bit too much templating can result in code that is cleaner, but harder to reason about when reading it back after a month.
For example, using C++ 20 ranges over simple loops is an example of where brevity and “cleanliness” can reduce clarity because the heavy templating and operator overloading hides what the code actually does.
On the other hand, sometimes one can’t avoid the complexity when writing a library that aims to work on many platforms, and with special tricks such as SIMD, as is present in the Eigen library.
Re: Fun with C++26 reflection: Keyword Arguments
#24Earlier quoted context omitted.
Reflection is such an insanely useful tool that pretty much all modern languages have it. As usual C++ is 20 years behind language design and brings terrible syntax. But it is tremendously useful. https://en.wikipedia.org/wiki/List_of_reflective_programming...
Isn't the reason why so many other languages have reflection due to the fact that they essentially have the information there from the get-go? For example, C# and Java have their intermediate language that has a bunch of meta information attached to it already or the info can be added easily if need be. Is C++ not more raw in its compilation process from code to object files? I mean sure, I guess meta-data could be a…
When I started out programming in C#, I used reflection sometimes to circumvent the language’s design and restrictions. This resulted in brittle and hard to reason about code. Reflection should never be used to do this.
So I do think you’re right that reflection can (and will) be abused by beginners if present as a language feature.
With that said, I don’t know much about the internals of the C++ compiler, but having built a simple reflection system for C++, I think the important thing is just being able to serialize and deserialize POD structs to and from some representation (e.g. json). For more advanced data, such as images or specific binary (file) formats, it’s easier to write custom writing / reading, encoding / decoding logic.
Re: Fun with C++26 reflection: Keyword Arguments
#25Earlier quoted context omitted.
Reflection is such an insanely useful tool that pretty much all modern languages have it. As usual C++ is 20 years behind language design and brings terrible syntax. But it is tremendously useful. https://en.wikipedia.org/wiki/List_of_reflective_programming...
Isn't the reason why so many other languages have reflection due to the fact that they essentially have the information there from the get-go? For example, C# and Java have their intermediate language that has a bunch of meta information attached to it already or the info can be added easily if need be. Is C++ not more raw in its compilation process from code to object files? I mean sure, I guess meta-data could be a…
C++ compilers also had this information since forever(basically reflection is giving to the end user some level of access to the AST nodes information) - the objections against reflection were always more political or about end-user design of the feature.
Re: Fun with C++26 reflection: Keyword Arguments
#26Earlier quoted context omitted.
I've seen cases where people do things like my_func(/*arg1=*/val1,/*arg2=*/val2) And I suppose you could write a validator to make sure that this worked. Or using an anonymous structure in C99, or a named structure in C89. And of course a pointer if you care about register/stack usage etc. I'm not sure what the other options are.
at that point why not just pass in a struct as your argument
depending on the platform this may cause things to be pushed / poped on the stack instead of being passed as registers
Re: Fun with C++26 reflection: Keyword Arguments
#27There are tons of more insightful examples in the proposal[0]. C++26 reflection could replace most meta programming tricks, though the syntax isn't the most pleasant.
Re: Fun with C++26 reflection: Keyword Arguments
#28I just don't understand why some people are so fascinated by this. Can you all admit that this is not at all practical? I swear C++ folks like it for the sake of it. No other engineer do this. Only antiques people or whatever. Can you imagine an engineer that is adamant on using his mystifying bespoke tool instead of just using a ruler. "But what if I have to measure it in the 4th dimension!?". I was expecting someth…
Honestly, all I ever want is to be enumerate a struct data member or an enum at compile time, and be able to get the name, type and value of each iterated member. That's it. That's all I want.
Re: Fun with C++26 reflection: Keyword Arguments
#29Earlier quoted context omitted.
I suppose it depends on your application. I worked in embedded devices where stack was limited and the compiler was .... less than reliable about how it would manage passing a large struct to your function, which is why I mentioned passing in a pointer instead
yes a pointer to struct would be acceptable as well
In 1998 perhaps. It wouldn't be acceptable to today's C++ value-semantics crowd. Are you sure that you want to take the indirection penalty? or that the compiler will optimise it away?
Re: Fun with C++26 reflection: Keyword Arguments
#30Earlier quoted context omitted.
Reflection is such an insanely useful tool that pretty much all modern languages have it. As usual C++ is 20 years behind language design and brings terrible syntax. But it is tremendously useful. https://en.wikipedia.org/wiki/List_of_reflective_programming...
Isn't the reason why so many other languages have reflection due to the fact that they essentially have the information there from the get-go? For example, C# and Java have their intermediate language that has a bunch of meta information attached to it already or the info can be added easily if need be. Is C++ not more raw in its compilation process from code to object files? I mean sure, I guess meta-data could be a…
>Isn't the reason why so many other languages have reflection due to the fact that they essentially have the information there from the get-go?
C++26 reflection is compile-time reflection, not runtime reflectiom, it doesn't require any extra information in the binary. It just uses information that the compiler already has at compilation time.