SendMessage ?

In the file windows_gui.rb of the home_stretch, there are two def_api(s) for the SendMessage:

def_api 'SendMessage',         ['L', 'L', 'L', 'P'], 'L', :send_with_buffer

def_api 'SendMessage',         ['L', 'L', 'L', 'L'], 'L'

The win32api is:
LRESULT WINAPI SendMessage( __in HWND hWnd, __in UINT Msg, __in WPARAM wParam, __in LPARAM lParam
);

The only difference between the two def_api(s) is the fourth parameter, one is ‘P’, and the other is ‘L’.

The first def_api is noted as sent_with_buffer. I wonder if that makes the fourth parameter different.

- Dat

Hi, Dat.

The meanings of the wParam and lParam parameters depend on which Windows message you’re sending. For WM_GETTEXT, lParam is a pointer to a buffer to receive the control’s text, so it’s defined in Ruby as 'P'. For the other Windows messages used in the book, it’s used as a long integer, 'L'.

—Ian