2.9 Traits ¶

Traits are extensions to the D programming language to enable programs, at compile time, to get at information internal to the compiler. This is also known as compile time reflection.

GNU D implements a __traits(getTargetInfo) trait that receives a string key as its argument. The result is an expression describing the requested target information.

version (OSX)
{
    static assert(__traits(getTargetInfo, "objectFormat") == "macho");
}

Keys for the trait are implementation defined, allowing target-specific data for exotic targets. A reliable subset exists which a D compiler must recognize. These are documented by the D language specification hosted at https://dlang.org/spec/traits.html#getTargetInfo.

The following keys are recognized by GNU D.

cppRuntimeLibrary

The C++ runtime library affinity for this toolchain.

cppStd

The version of the C++ standard supported by extern(C++) code, equivalent to the __cplusplus macro in a C++ compiler.

floatAbi

Floating point ABI; may be ‘hard’, ‘soft’, or ‘softfp’.

objectFormat

Target object format.