Re: handler for dynamically created button

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 18 May 2007 09:40:37 -0400

Message-ID:

<3sWdnXMc9PhKMdDbnZ2dnUVZ_tOmnZ2d@comcast.com>

buly wrote:

Thank you, I searched bug which I had in my code.

And if I want to define buttons event dynamically, how can I do it? E.g. I
have many events methods defined in my project and I have dynamic dialog
which is parsed from xml file. One of parameters there is name of method
which will be called when button will be clicked.
I thought that I will define struct array which will be returned by
GetThisMessageMap.

I defined:
static AFX_MSGMAP_ENTRY _messageEntries[100];

and I filled structure in by
void CEventDialog::addEvent(int itemId, char *method)
{
    if( m_iEventCount < MAX_EVENT )
    {
        _messageEntries[m_iEventCount].nMessage = WM_COMMAND;
        _messageEntries[m_iEventCount].nCode = (WORD)BN_CLICKED;
        _messageEntries[m_iEventCount].nID = (WORD) itemId;
        _messageEntries[m_iEventCount].nLastID = (WORD) itemId;
        _messageEntries[m_iEventCount].nSig = AfxSigCmd_v;
        _messageEntries[m_iEventCount].pfn = (static_cast< AFX_PMSG > (method));

        _messageEntries[m_iEventCount+1].nMessage = 0;
        _messageEntries[m_iEventCount+1].nCode = 0;
        _messageEntries[m_iEventCount+1].nID = 0;
        _messageEntries[m_iEventCount+1].nLastID = 0;
        _messageEntries[m_iEventCount+1].nSig = AfxSig_end;
        _messageEntries[m_iEventCount+1].pfn = (AFX_PMSG)0;

        m_iEventCount++;
    }
}

but in line
_messageEntries[m_iEventCount].pfn = (static_cast< AFX_PMSG > (method));
there is error:
error C2440: 'static_cast' : cannot convert from 'char *' to 'AFX_PMSG'

Do you have any idea how to do it?
Thanks

I have no idea how to dynamically create a message map, but you
certainly can't use a character string that names the function. The
struture needs a function pointer, which is the address of the actual
function. Function names do not exist at run time, only function
addresses. You would have to add another table to let you look up a
function address from a function name.

An easier approach that you could consider is to use macros like
ON_CONTROL_RANGE and ON_COMMAND_RANGE in a message map at design time.
They would let you allocate a certain range of IDs for a control type,
such as up to 100 buttons, and then handle them all with just one line
in the map:
ON_CONTROL_RANGE(BN_CLICKED, IDC_BUTTON1, IDC_BUTTON100, OnBtnCLick)

--
Scott McPhillips [MVP VC++]