Re: [Boost-users] Problem with boost::signal. How to call just one slotin signal

8 Jun 2005


      ...
Allow me to offer a suggestion from what I understand of your description of the problem:
1- For your special callback, save it off somewhere as a boost.function<>
2- then call the boost.function<> you have saved before calling your signals
Although you said you didn't fully understant my question, I managed
to solve my problem with your suggestions =)

I basicly used boost.function<> instead of the .slot_type, and
for my luck, boost.signal.connect( ) accepted boost.function<>
as it's parameter :)

Thanks alot,
...
Brian
...
-----Original Message-----
From: boost-users-bounces@lists.boost.org [mailto:boost-users-
bounces@lists.boost.org] On Behalf Of Juho Mäkinen
Sent: Monday, June 06, 2005 11:56 PM
To: boost-users@lists.boost.org
Subject: [Boost-users] Problem with boost::signal. How to call just one
slotin signal
Hello.
I'm having problems with boost::signal. I have a simple callback
system:
typedef boost::signal<void (const String &)> StringCallbacks;
TSharedPtr<StringCallbacks> stringCallbacks;
stringCallbacks contains void (Const String &) -callback functions.
New callback functions are registered into the callback system with
registerCallback -function:
template<class VarType>       class SettingUpdater {
  private:
    VarType & reference;
SettingUpdater(VarType & var) : reference(var) { }
public:
    void operator()(const String & setting)
    {
       // do someting irrelevant for the question here
       // with the reference -variable
    }
};
boost::signals::connection registerCallback(StringCallbacks::slot_type
callback)
{
  // PROBLEM: I'd like to call the callback once without calling every
callback
  // which are possibly registered already into the signal before this.
// Register the new callback into the signal.
  return stringCallbacks.get()->connect(callback);
}
The actual usage of registerCallback:
int localVariable;
registerCallback(SettingUpdater<int>(localVariable));
Question:
As you might already see above, I'd like to call the callback function
once in the registerCallback function without calling every callback
already registered in the stringCallbacks signal.
I first tried something like
String param = "foo";
callback(param);
but that won't compile.
I also tried callback.get_slot_function()(param);
That compiles, but it won't execute the operator() -function in
SettingUpdater.
Calling the signal will execute all callbacks registered, so the
SettingUpdater
function seems working. How I can execute the operator() function
in SettingUpdater<> inside registerCallback function by the
callback parameter passed to registerCallback function?
Thanks in advance =)
- Juho Mäkinen
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