one signal to two slots for reading and logging in a file

[QJak]

hi
I want to read from serial port (rs232) then processing and in the same time saving in a file. one way is using QThread but could i use "readyRead" signal with two slots like this instead of QTread?

signal(readyRead) , slot(doing some things and processing)

signal(readyRead) , slot(saving_file())

[high_flyer]

I don't know what threads have to do with the question.
Any way, have a look at the signal/slot documentation.
If you do, you will see you can connect any signal to any number of slots.
So yes, you can connect your readyRead() signal to two different slots.

[Lesiok]

But if in the first slot you do readAll() on the serial port then in the second you will not read anything from the port.

[QJak]

thanks. i need to read in two slots. but in first slot after reading, i do some processing and in second slot after reading i need to put it into a file.
if i understand your answer, you mean is that second slot can not read?

[Lesiok]

Yes. Why not to use one slot and simple call logging method from slot ?

[QJak]

realy thanks. please help me to do this. how can i use a slot and call saving into a file?

[Lesiok]

Slot is normal class method. So in body call some another method with QByteArray argument to save data to file.
These are the basics of C++.

[QJak]

thanks again. you mean i call saving function from body of slot? (i need to do two works (1-reading and processing 2-reading and writing in a file) together like tread.
please explain more

[Lesiok]

Yes. In slot You need :

1. Read data from port.
2. Process data.
3. Write data in a file.

Steps 2 and 3 can be swapped.

[QJak]

thanks but processing and writing after that is too slow. i need to do 2 jobs in the same time
is this work correct to emit a signal after reading like this:
i define a signal in name of : signal_saving(QByteArray) and connect this signal to the second slot below
then define 2 slots: slot1_readingAndProcessing() , slot2_saving(QByteArray)
after connecting signal_saving(QByteArray) to slot2_saving(QByteArray) i emit this signal after reading data in body of first slot. imean:
slot1_readingAndProcessing()
{
reading data and put in QByteArray
emit signal_saving(QBytArray)
then processing
}


is this correct?

[Lesiok]

Yes, this is correct under one condition : connection to slot2_saving is in Qt::QueuedConnection. In Qt::DirectConnection emiting a signal is equivalent to calling the method. Read documentation.

[QJak]

this way has not my desier result (working paralel). please help me

[d_stranz]

...thanks but processing and writing after that is too slow. i need to do 2 jobs in the same time...

...working paralel...

please help me

Please explain why you insist this must be a parallel operation (you say so here and in your other posts). What is your "processing" that makes it so slow? And writing a small amount of data to a log file should be very fast, unless you are opening and closing the file for every write.

Based on what you are asking and how you are asking it, I am not sure you understand enough to write a multi-threaded application that will work correctly.