QSignalMapper

[Ali Reza]

hi all

i want to make a multi-stream http proxy. i faced to a problem.
my problem is about "look up host"
i used QHostInfo to do this.(function LookupHost(...))
as we know this function emit a signal that have one parameter (QHostInfo &)
but i want connect each stream look up to it's own function
in other words i want this slot:

void LookUpResult(QHostInfo @hi , int id)

void LookUpResult(QHostInfo @hi , int id)

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that id is the identifier of a specific stream.
how to implement this??
please help

thanks in advance.

[Ginsengelf]

Hi, I don't think you can do that with QSignalMapper.
As a (little bitugly) work-around you can connect all signals to one slot and use sender() to check which stream sent the signal.

Ginsengelf

[Ali Reza]

hi Ginsengelf
thanks for replying

please explain more. i do not understand what your mean !

thanks again...

[Ali Reza]

help me!!!
i do not take my answer.
please offer me a solution... or a new approach or ...

regards

[amleto]

hi all

i want to make a multi-stream http proxy. i faced to a problem.
my problem is about "look up host"
i used QHostInfo to do this.(function LookupHost(...))
as we know this function emit a signal that have one parameter (QHostInfo &)
but i want connect each stream look up to it's own function
in other words i want this slot:

void LookUpResult(QHostInfo @hi , int id)

void LookUpResult(QHostInfo @hi , int id)

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that id is the identifier of a specific stream.
how to implement this??
please help

thanks in advance.

just copy the example in the docs

qsignalmapper

[Ali Reza]

this link get me 404 not found !!!

[amleto]

changed it.

not sure exactly what you're trying to do, though. There needs to be something that knows the id to use, but you dont show where that is in your code

[Ali Reza]

how to implement with QSignalMapper ?? (if possible)

[amleto]

Why do you want

void LookUpResult(QHostInfo hi , int id)

when id = hi.lookupId()?*

*I believe this is true but I'm not certain.

[Ali Reza]

i want to implement a multi stream HTTP proxy that accept many connections from the browser.
my proxy must look up IP address of the host that specified by each TCP stream (for each http request from browser)
thus i must look up the ip for each stream concurrently
i used QHostInfo ( method LookUpHost() ).
now i want connect the result of this function to my customized slot:

void LookUpResult(QHostInfo @hi , int id)

void LookUpResult(QHostInfo @hi , int id)

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how ???

thanks

[amleto]

well, you were given the id earlier when you called lookupHost. so save 'id', and when you receive HostInfo you will be ready to call that slot.

[Ali Reza]

please explain to me by coding. i do not understand your mean.
thanks

[amleto]

tell me, what is the difference between

hostinfo.lookupId() and your 'int id' in void LookUpResult(QHostInfo @hi , int id)??

I say there is no difference!

Therefore you don't need

void LookUpResult(QHostInfo @hi , int id)

void LookUpResult(QHostInfo @hi , int id)

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because you can use

void LookUpResult(QHostInfo hi)
{
  int id = hi.lookupId();
  // ...
}

void LookUpResult(QHostInfo hi)
{
  int id = hi.lookupId();
  // ...
}

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[Ali Reza]

sorry for my bad English.

my 'id' is a identifier of a stream that established by a internet browser.
i don't know the hostinfo.lookuoid() is what !
please tell me the above function what returns.

thanks

---

Added after 5 minutes:

thanks dear amleto
i understand what you say
my problem solved .

thanks very very much...

[amleto]

sorry, finally I think I understand your problem. I think what I suggested above might not work as you want.

class MyMapper : QObject
{
// Q_OBJECt etc
 
public:
  MyMapper(int id) : id_(id) {}
 
 
public slots:
  void myResultLookup(QHostInfo info)
  {
    //...
    resultLookup(info, id_);
    deleteLater(); // this object no longer needed?
  }
 
private:
  int id_;
 
};
 
void YourMethod()
{
 
  int streamId = ...;
  QString hostname = ...;
  MyMapper* mapper = new MyMapper(streamId);
  QHostInfo::lookupHost(hostname, mapper, SLOT(myResultLookup(QHostInfo)));
}

class MyMapper : QObject
{
// Q_OBJECt etc

public:
  MyMapper(int id) : id_(id) {}


public slots:
  void myResultLookup(QHostInfo info)
  {
    //...
    resultLookup(info, id_);
    deleteLater(); // this object no longer needed?
  }

private:
  int id_;

};

void YourMethod()
{

  int streamId = ...;
  QString hostname = ...;
  MyMapper* mapper = new MyMapper(streamId);
  QHostInfo::lookupHost(hostname, mapper, SLOT(myResultLookup(QHostInfo)));
}

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[Ali Reza]

thanks again ...
solved !

---

Added after 4 minutes:

hey amleto
excuse me, another problem
is there any way to IP caching in Qt Creator ?

[amleto]

not sure. probably time for a new thread!

[Ali Reza]

Hey amleto
*** NOT SOLVED ***
your snipped code about Host look up is wrong.
in definition of myResultLookup from Mapper class ,you call resultLookup. but this function is member of another class!!
what can i do?

regards

[amleto]

My code isn't wrong, it's just not complete. That function comes from your code. you figure out how to pass it in

[Ali Reza]

excuse me !
i did not understand
1.you define a new class that named "MyMapper" that inherits "QObject". but this definition get me the following error:
" 'QObject' is an inaccessible base of 'MyMapper' ".
2.you call function "resultLookup(info, id_);" in line 13 in your code. but this function is not accessible here (this function is member of another class)

plz tell me how your code is right ?

thanks alot dear amleto !