C++

1755 readers
1 users here now

The center for all discussion and news regarding C++.

Rules

founded 1 year ago
MODERATORS
126
-1
The Myth of Smart Pointers (www.logikalsolutions.com)
submitted 10 months ago by lysdexic to c/cpp
127
128
129
130
131
30
submitted 11 months ago by lysdexic to c/cpp
132
133
134
 
 

Jack London once said, "You can't wait for inspiration. You have to go after it with a club". When it comes to game development, the SDL project may well be such a club. How is it made, though?

What bugs does SDL have? And what Sam Lantinga says about it?

https://pvs-studio.com/en/blog/posts/cpp/1081/

@cppguide
@cpp
@c_discussions

135
10
submitted 11 months ago by lysdexic to c/cpp
136
13
submitted 11 months ago* (last edited 11 months ago) by lawmurray to c/cpp
 
 

C++ trick I pulled today. Like an explicit constructor but context dependent. Any alternatives from folks who've needed to do similar? One thing I still need to dig into a little deeper is how copy elision behaves here.

137
13
submitted 11 months ago by lysdexic to c/cpp
138
139
140
141
 
 

An excellent talk by Timur about type punning, the UB weirdness that accompanies it and attempts at doing something similar with modern C++ without UB (which led to std::bit_cast and other proposals) while revisiting notions like aliasing and alignment.

142
10
submitted 11 months ago by lysdexic to c/cpp
143
144
11
submitted 11 months ago by lysdexic to c/cpp
145
 
 

If you're writing code that's doing lots of memory allocations (e.g. lots of nodes being created in some huge graph at runtime and/or you're also doing lots of type erasure, and most importantly you can't know in advance how many you'll need) then you might wanna take a look at C++17's std::pmr instead of trying to write your own allocators (which is still a good idea if the goal is just to learn).

In particular, what would interest you the most are the memory resources themselves, which are in the memory_resource header file (https://en.cppreference.com/w/cpp/header/memory_resource ).

I had great success using in particular unsynchronized_pool_resource (perfect in single-threaded settings where you're sure you don't want other threads to access that resource) and monotonic_buffer_resource (perfect when you don't care about reusing previously freed memory and care more about speed, so that the cost of one allocation is then just a pointer increment inside a buffer and "deallocation" is a no-op) in our production code and, depending on the scenario, achieved speedups between x2 and x3 compared to using the standard allocator.

You can directly use the .allocate and .deallocate member functions of those resources (although the semantics will be a bit different from your usual malloc and free, as you need to remember the alignment and the size of the allocated space when you want to deallocate). You also have standard containers inside std::pmr that can be bound to one of those memory resources in a type-erased way (hence the "polymorphic" in the name), like std::pmr::vector or std::pmr::list.

There's also an awesome CppCon talk by John Lakos in two parts which explains those allocation strategies:

146
147
12
submitted 1 year ago by lysdexic to c/cpp
148
16
submitted 1 year ago by lysdexic to c/cpp
149
150
12
submitted 1 year ago by lysdexic to c/cpp
 
 

TL;DR

At last the experiment is over, and CMake 3.28 has official support for C++ 20 named modules enabled without having to set the CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API variable.

view more: ‹ prev next ›