Best method for storing this pointer for use in WndProc

Question

I\'m interested to know the best / common way of storing a this pointer for use in the WndProc. I know of several approaches, but each as I underst

Answer 1

You can use GetWindowLongPtr and SetWindowLongPtr; use GWLP_USERDATA to attach the pointer to the window. However, if you are writing a custom control I would suggest to use extra window bytes to get the job done. While registering the window class set the WNDCLASS::cbWndExtra to the size of the data like this, wc.cbWndExtra = sizeof(Ctrl*);.

You can get and set the value using GetWindowLongPtr and SetWindowLongPtr with nIndex parameter set to 0. This method can save GWLP_USERDATA for other purposes.

The disadvantage with GetProp and SetProp, there will be a string comparison to get/set a property.