Re: Check existence of data area in ILE C

It makes no sense to me why you resolve a pointer to the data area to 
check existence but then use a retrieve api to get the contents? Why not 
just monitor for the exception on the retrieve function? You can remove 
the message in the handler using something like this:

_INTRPT_Hndlr_Parms_T *errmsg
   QMHCHGEM(&(errmsg->Target), 0, (char *)&errmsg->Msg_Ref_Key, 
"*REMOVE   ", "", 0,  errStruct);


On 3/10/2015 4:36 PM, CRPence wrote:
> On 10-Mar-2015 10:20 -0500, Zvi Kave wrote:
>> Sorry. It is too much complicated for me.
>> Waiting for simpler solution.
>> Perhaps a change in the exception handler?:
>>  #pragma exception_handler(ERROR_OCCURED, ca, 0, _C2_MH_ESCAPE, \
>>                              _CTLA_HANDLE, "MCH3401")
>>
>
>   Of course that would not resolve the issue of concurrency introduced 
> by performing a separate /check for existence/ test prior to invoking 
> the request to /Retrieve Data Area/ that itself performs the same 
> existence check.  Nevertheless...
>
>   I was unaware that the capability to suppress the messaging was 
> exposed externally in any of the HLLs, but a quick search of the 
> KnowledgeCenter revealed that there are both of the Exception Control 
> Actions available to the C language, "_CTLA_IGNORE_NO_MSG" and 
> "_CTLA_HANDLE_NO_MSG", which apparently provide the equivalent effect 
> of the message suppression:
> <http://www.ibm.com/support/knowledgecenter/ssw_ibm_i_71/rzarf/prag_exception_handler.htm%23prag_exception_handler> 
>
> "...
> ctl_action
>
>     Specifies an integer constant to indicate what action should take 
> place for this exception handler. If handler is a function, the 
> default value is _CTLA_INVOKE. If handler is a label, the default 
> value is _CTLA_HANDLE. This parameter is optional.
>
>     The following are valid exception control actions that are defined 
> in the <except.h> header file:
>
>     #define name     Defined value and action
> ...
> _CTLA_HANDLE_NO_MSG     Defined to 3. The exception is handled but 
> messages are not logged before calling the handler. The exception will 
> no longer be active when the handler gets control. Exception messages 
> are not logged. Msg_Ref_Key in the typedef _INTRPT_Hndlr_Parms_T is 
> set to zero. Exception processing ends when the exception handler 
> returns. This is valid for functions and labels.
>  ...
> _CTLA_IGNORE_NO_MSG     Defined to 132. The exception is handled and 
> messages are not logged. Control is not passed to the handler function 
> named on the directive and exception will no longer be active. 
> Execution resumes at the instruction immediately following the 
> instruction that caused the exception. This is valid for functions only.
>  ..."
>

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