Lords Of Tech

Category: Programming

You can define template methods in .cpp files without explicit instantiation, as long as they are private

For years I’ve been programming in C++ with the belief that the bodies of template methods had to be in headers. Only recently I learned that splitting template methods between header and source is, in fact, often perfectly fine.
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C++20 Resumable functions: Goodbye state machines, no one will mourn you

C++20 allows writing functions that suspend and can continue at the next line. This has an amazing application at avoiding writing annoying and error-prone state machines. This article showcases how coroutines can clean up a function that would usually need an ugly state machine.
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Error codes are far slower than exceptions

TL;DR On modern 64-bit PC architectures, C++ exceptions only add unreachable code with destructor calls into functions and their effect on performance is below 1%, but such low values are difficult to measure. Handling rare errors with return values requires additional branching that slows down the program in realistic scenarios by about 5% and are also less convenient. If an exception is actually thrown, stack unwinding costs about 2 µs per stack frame.
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