How can I use SerialPortError to get a human readable text in QSerialPort 5.2? The only thing I know is error() returns enum. I have the list of the errors in Qt documentation. I don't want to reinvent the wheel. For example, 1 indicates accessing to non existed port.
QIODevice, the parent class of QSerialPort, has an errorString() method. The documentation states:
Returns a human-readable description of the last device error that occurred.
Unfortunately, a quick glance through the code reveals that QSerialPort does not set the error string when it sets the error code. It looks like you will need to generate the error strings yourself.
errorString() may still return a valid error string if the error was set by QIODeivce instead of QSerialPort.
Related
When It is possible to define a custom ErrorCollector class for handling google::protobuf parsing errors
struct ErrorCollector : ::google::protobuf::io::ErrorCollector
{
void AddError(int line, int column, const std::string& message) override
{
// log error
}
void AddWarning(int line, int column, const std::string& message) override
{
// log warning
}
};
When parsing from a text file, you can use the protobuf TextFormat class and register your custom ErrorCollector
::google::protobuf::io::IstreamInputStream input_stream(&file);
::google::protobuf::TextFormat::Parser parser;
ErrorCollector error_collector;
parser.RecordErrorsTo(&error_collector);
if (parser.Parse(&input_stream, &msg))
{
// handle msg
}
For parsing wire format, I currently use Message::ParseFromArray
if (msg.ParseFromArray(data, data_len))
{
// handle msg
}
This doesn't allow me to specify a custom ErrorCollector though.
I've searched through the source code, but as of yet have been unable to find if this is possible.
Is it possible to use an ErrorCollector when parsing wire format?
Is there another way to intercept parse errors and make them available to client code?
There are essentially two ways that parsing the wire format could fail:
The bytes are not a valid protobuf (e.g. they are corrupted, or in a totally different format).
A required field is missing.
For case 1, protobuf does not give you any more information than "it's invalid". This is partly for code simplicity (and speed), but it is also partly because any attempt to provide more information usually turns out more misleading than helpful. Detailed error reporting is useful for text format because text is often written by humans, but machines make very different kinds of errors. In some languages, protobuf actually reports specific errors like "end-group tag does not match start-group tag". In the vast majority of cases, this error really just means "the bytes are corrupted", but inevitably people think the error is trying to tell them something deeper which they do not understand. They then post questions to stack overflow like "How do I make sure my start-group and end-group tags match?" when they really should be comparing bytes between their source and destination to narrow down where they got corrupted. Even reporting the byte position where the parse error occurred is not very useful: protobuf is a dense encoding, which means that many random corrupt byte sequences will parse successfully, which means the parser may only notice a problem somewhere later down the line rather than at the point where things actually went wrong.
The one case that clearly is useful to distinguish is case 2 (missing required fields) -- at least, if you use required fields (I personally recommend avoiding them). There are a couple options here:
Normally, required field checks write errors to the console (on stderr). You can intercept these and record them your own way using SetLogHandler, but this doesn't give you structured information, only text messages.
To check required fields more programmatically, you can separate required field checking from parsing. Use MessageLite::ParsePartialFromArray() or one of the other Partial parsing methods to parse a message while ignoring the absence of required fields. You can then use the MessageLite::IsInitialized() to check if all required fields are set. If it returns false, use Message::FindInitializationErrors() to get a list of paths of all required fields that are missing.
I am trying to use an ActiveX control in my program.
QAxWidget* mAX = new QAxWidget();
mAX->setControl("{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}");
I know that there is a function:
put_ChannelType(long newValue)
But when I try to execute it:
mAX->dynamicCall("put_ChannelType(long)",2);
mAX->dynamicCall("put_ChannelType(int)",2);
mAX->dynamicCall("put_ChannelType(long)",QVariant(2));
mAX->dynamicCall("put_ChannelType(int)",QVariant(2));
I get:
QAxBase: Error calling IDispatch member put_ChannelType: Bad parameter count
Any idea what is going wrong ?
EDIT:
Weird thing is if I call
mAX->dynamicCall("put_ChannelType()");
I do not get any error message...
EDIT 2:
This also fails (as Constantin suggested)
QList<QVariant> varlist;
varlist << (int)1;
mAX->dynamicCall("put_ChannelType(int)",varlist);
Got this solved using the generateDocumentation() function.
I was using this ActiveX control in another application, but an MFC one.
It seems the function names I was referring to (which were in a machine generated IDispatch wrapper class created by VS) were not the same as the ones Qt listed.
i.e. put_ChannelType is actually SetChannelType...
Maybe this is just a version issue ?
Anyways, important part is knowing that generateDocumentation() can list you all the functions you can call with dynamicCall.
Is it OK?
mAX->dynamicCall("put_ChannelType(const QVariant &)", (long)2);
I am trying to determine if a given XML file is valid (has proper syntax and structure), and I am using Xerces. I have been able to succesfully read proper files but when I give it files with incorrect syntax, no errors are thrown.
I have been fishing around and found out that I might have to use an Error handler and user setErrorHandler to catch the errors instead of the traditional try-throw-catch exception handling.
The problem that I am having though is that I am very confused how to declare the proper handler, set it to my parser and then read the errors if there are any that show up.
Is there any chance somebody could shed some light on my situation?
// #input_parameter from function: const string & xmlConfigArg
xercesc::DOMDocument* doc = NULL;
string xmlConfig(xmlConfigArg);
Handler handler; // I'm not sure what type of handler to use
_parser->setErrorHandler(&handler);
try{
_parser->parse(xmlConfigArg.c_str());
doc = _parser-> getDocument();
}catch(...){
//Nothing is ever caught here
}
You need to derive a class from ErrorHandler (< xercesc/sax/ErrorHandler.hpp >)
then overwrite all the virtual methods there.
After doing so, You can get the error code from the class you created. No exceptions will be thrown in the parsing, so you can wave the try/cache block (or keep it for a different use).
I'm trying to connect a wxListCtrl event to a function in C++, and it should be straightforward. Generally using Connect() works, but for one reason or another, it isn't recognizing the event name (EVT_LIST_ITEM_SELECTED). I've included wx/listctrl.h, and even checked to make sure the event is listed (it is; not in listctrl, but in listbase which is included in listctrl).
Here is the problem line:
parent->Connect (ID_Objects, wxEVT_LIST_ITEM_SELECTED, (wxObjectEventFunction) &Editor::objectSelected);
The specific error is that identifier "wxEVT_LIST_ITEM_SELECTED" is undefined. The parent is a wxFrame.
In other places, I've used the same syntax but with a different event type and it worked fine.
So what am I doing wrong?
try
wxEVT_COMMAND_LIST_ITEM_SELECTED
Ensure that <wx/listctrl.h> is included in the file that contains parent->Connect (ID_Objects, wxEVT_LIST_ITEM_SELECTED, ...
c++
mfc
if CHttpConnection::OpenRequest returns a null what can I use to get the internet error.
The mfc artical doesn't say what a bad responce looks like. I just said it returns a handle to a CHttpFile.
Did you see what is the error code returned by GetLastError() ? Get the error code and perform a error lookup (Tools->Error Lookup) to get the description about the code. Normally you will get the exact reason for the failure using this.