Calypso/TipsAndTricks

Constructing C++ classes or structs inside malloc'd memory

When a C++ library expects to be granted ownership of a piece of memory, the allocation shouldn't be done by the GC unless you always keep a reference to the allocated memory, which is pointless additional work and not always possible.

Calypso provides a small runtime library which contains some commonplace utility functions, such as cppNew and cppDelete to bypass the GC while constructing C++ class/struct objects:

import cpp.memory; // cppNew and cppDelete
import (C++) std.unique_ptr;

auto testClass = cppNew!MyCppClass(...); // malloc then ctor call
unique_ptr!MyCppClass owner;
owner.reset(testClass);

// testClass will be free'd by the owner's dtor