Re: data in g_signal_connect

[<olafandjasper hushmail com>]

Thank you all very much...Both of your posts helped... John I un-globalized
and Olexiy used the correct API/proto.
O

On Thu, 13 Nov 2003 08:31:23 -0800 John Cupitt <john cupitt ng-london org uk>
wrote:
>Hi, you're creating an instance of MY_DATA in the header file, then
>including that header in two places. So you're getting two versions
>of MY_DATA. You should never make variables in headers, only declare
>that they exist elsewhere (with an extern).
>
>Remove the line "struct MY_DATA mydata;" from the header, and remove
>the "extern" from the declaration in SQLstuff.c.
>
>In any case, it's probably not wise to use globals like this. It's
>better to g_new( MY_DATA ) to allocate a new one off the heap, and
>then make sure you g_free() it somewhere sensible.
>
>HTH,
>
>John
>
>olafandjasper hushmail com wrote:
>> Hello again:
>> This is a follow-up of a previous thread I started in early Nov.
>> I appreciate the help I got from the list, but I am still having
>difficulty.
>> Someone suggested I use a different prototype, but I got the same
>(wrong)results:
>>    void slectActionBin (GtkWidget     *widget,
>>                         GdkEvenButton *event,
>>                         MY_DATA       *data)
>> 
>> The problem is the data is not being printed out in the callback
>routine.
>> You can see, at the bottom of this post, that there is
>> nothing in data and the address is diff :(
>> 
>> Can someone help get my data so it is visable/correct in the called
>cb
>> routine.
>> I think (maybe) I am not casting it properly or something, but
>when I
>> called the callback routine directly (commented out the g_connect_signal)
>> the data was correct....hmmmm
>> 
>> Here is the code that does not work:
>> =========================================================
>> mySupport.h:
>> struct MY_DATA {
>>    char bin[1000];
>>    char doc[1000];
>> };
>>                                                              
>      
>>            
>> struct MY_DATA mydata;
>> 
>> =========================================================
>> mySupport.c:
>> void selectActionBin(GtkWidget      *button,
>>                      struct MY_DATA *data)
>> {
>>   /* This is the code that does not work */
>>   printf("In call back, data = <%s>\n",data->bin);
>>   printf("In call back, data = <%s>\n",data->doc);
>>   printf("In call back, data is at %p\n", data);
>>   printf("In call back, &data is at %p\n", &data);
>> }
>> =========================================================
>> SQLstuff.c:
>> -- This is where I set up my callback/data 
>> extern struct MY_DATA mydata;
>> int doQuery(char *sqlStr)
>> {
>>   strcpy(mydata.bin,"Test data");
>>   strcpy(mydata.doc,"Test data");
>>   printf("Data is <%s> before callback\n",mydata.bin);
>>   printf("Data is <%s> before callback\n", mydata.doc);
>>   printf("Data is at %p before callback\n", mydata);
>>   printf(" &data is at %p before callback\n", &mydata);
>>   g_signal_connect(G_OBJECT (butWidget),
>>                    "button_press_event",
>>                    G_CALLBACK (selectActionBin),
>>                    &mydata);
>> }
>> =========================================================
>> output: (as you can see the callback is called but nothing is
>>          in the data and the address are diff) :(
>> 
>> Data is <Test data> before callback
>> Data is <Test data> before callback
>> Data is at 0x74736554 before callback
>> &data is at 0x80513a0 before callback
>> 
>> In call back, data = <>
>> In call back, data = <>
>> In call back, data is at 0x8a3e6e0
>> In call back, &data is at 0xbfffd944
>> 
>> 
>> Thanks,
>> O
>> 
>> 
>> 
>> 
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>
>
>



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