Thread: Throw statement without a try statment to accompany it.

Hi there,

I've found some odd code in one of my projects.

Code:

#if defined(DEBUG) || defined(_DEBUG) 
	// Enable the D3D12 debug layer.
{
	ComPtr<ID3D12Debug> debugController;
	ThrowIfFailed(D3D12GetDebugInterface(IID_PPV_ARGS(&debugController)));
        D3D12GetDebugInterface(IID_PPV_ARGS(&debugController));
	debugController->EnableDebugLayer();
}

ThrowIfFailed is defined as:

Code:

#ifndef ThrowIfFailed
#define ThrowIfFailed(x)                                              \
{                                                                     \
    HRESULT hr__ = (x);                                               \
    std::wstring wfn = AnsiToWString(__FILE__);                       \
    if(FAILED(hr__)) { throw DxException(hr__, L#x, wfn, __LINE__); } \
}
#endif

And the class constructor passed to the throw call initializes the following class:

Code:

class DxException
{
public:
    DxException() = default;
    DxException(HRESULT hr, const std::wstring& functionName, const std::wstring& filename, int lineNumber);

    std::wstring ToString()const;

    HRESULT ErrorCode = S_OK;
    std::wstring FunctionName;
    std::wstring Filename;
    int LineNumber = -1;
};

All seems ok. Only trouble is I thought a throw call was usually in a block with a try statement. I can't find a try statement anywhere.

How is throw allowed to call like that without a try statement?

Thanks

Epic answer, thanks very much