Need help understanding code

Hi,

Could somebody tell me what this following code means (syntax wise)

MessageIOGateway :: MessageIOGateway(int32 encoding) :
   _maxIncomingMessageSize(MUSCLE_NO_LIMIT),
   _outgoingEncoding(encoding),
   _aboutToFlattenCallback(NULL), _aboutToFlattenCallbackData(NULL),
   _flattenedCallback(NULL), _flattenedCallbackData(NULL),
   _unflattenedCallback(NULL), _unflattenedCallbackData(NULL)
#ifdef MUSCLE_ENABLE_ZLIB_ENCODING
   , _sendCodec(NULL), _recvCodec(NULL)
#endif
{
   /* empty */
}


Thank you,
Riyaz

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 > Hi,
 >
 > Could somebody tell me what this following code means (syntax wise)
 >
 > MessageIOGateway :: MessageIOGateway(int32 encoding) :
 >    _maxIncomingMessageSize(MUSCLE_NO_LIMIT),
 >    _outgoingEncoding(encoding),
 >    _aboutToFlattenCallback(NULL), _aboutToFlattenCallbackData(NULL),
 >    _flattenedCallback(NULL), _flattenedCallbackData(NULL),
 >    _unflattenedCallback(NULL), _unflattenedCallbackData(NULL)
 > #ifdef MUSCLE_ENABLE_ZLIB_ENCODING
 >    , _sendCodec(NULL), _recvCodec(NULL)
 > #endif
 > {
 >    /* empty */
 > }

It's a constructor implementation, initializing a whole bunch of
members, and the class declaration probably has something like
the following:

#ifdef MUSCLE_ENABLE_ZLIB_ENCODING
    Foo *_sendCodec;
    Bar *_recvCodec;
#endif

-- 
A. Kanawati
 XXXX@XXXXX.COM 

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"Mohammed Riyaz" < XXXX@XXXXX.COM > wrote...
 > Could somebody tell me what this following code means (syntax wise)
 >
 > MessageIOGateway :: MessageIOGateway(int32 encoding) :
 >   _maxIncomingMessageSize(MUSCLE_NO_LIMIT),
 >   _outgoingEncoding(encoding),
 >   _aboutToFlattenCallback(NULL), _aboutToFlattenCallbackData(NULL),
 >   _flattenedCallback(NULL), _flattenedCallbackData(NULL),
 >   _unflattenedCallback(NULL), _unflattenedCallbackData(NULL)
 > #ifdef MUSCLE_ENABLE_ZLIB_ENCODING
 >   , _sendCodec(NULL), _recvCodec(NULL)
 > #endif
 > {
 >   /* empty */
 > }

Not sure which part you're finding puzzling.  Perhaps the colon and
the commas.  If so, look up "constructor initializer list" in your
favourite C++ book.

V


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 > Hi,
 >
 > Could somebody tell me what this following code means (syntax wise)
 >
 > MessageIOGateway :: MessageIOGateway(int32 encoding) :
 >   _maxIncomingMessageSize(MUSCLE_NO_LIMIT),
 >   _outgoingEncoding(encoding),
 >   _aboutToFlattenCallback(NULL), _aboutToFlattenCallbackData(NULL),
 >   _flattenedCallback(NULL), _flattenedCallbackData(NULL),
 >   _unflattenedCallback(NULL), _unflattenedCallbackData(NULL)
 > #ifdef MUSCLE_ENABLE_ZLIB_ENCODING
 >   , _sendCodec(NULL), _recvCodec(NULL)
 > #endif
 > {
 >   /* empty */
 > }

This is the constructor for the class "MessagelOGateway".
The constructor takes an int32 argument "encoding"
Everything after the ":" are member initialization

Joe



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> Could somebody tell me what this following code means (syntax wise)
This is just a constructor definition in a .cpp file for the
class MessageIOGateway.  What don't you understand?  There's
some uppercase items (constants? #defines?) and the #ifdef
that may be declared somewhere else, but it's still a ctor.

It's no different than this simplified class:

// X.h file
class X {
  X(int i);
  int _x, _y;
};

// x.cpp file
X::X(int i) : _x(i), _y(2)
{
}

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1. This is a constructor for the class MessageIOGateway : a "member 
function" having the same name as the class it is in is called a 
constructor.
See  http://www.**--****.com/ ++-faq-lite/ctors.html
2. All the stuff like _maxIncomingMessageSize(MUSCLE_NO_LIMIT) are 
initializations of members of the class.
See  http://www.**--****.com/ ++-faq-lite/ctors.html#faq-10.6
3. The #ifdef/#endif initializes some extra members if the symbol 
MUSCLE_ENABLE_ZLIB_ENCODING is defined.

HTH,
Julien

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It's the definition of a constructor of a class named MessageIOGateway 
with an extensive member initialization list and an empty body.

Which part are you having problems with?

-- 
Gerhard Menzl

#dogma int main ()

Humans may reply by replacing the obviously faked part of my e-mail 
address with "kapsch".

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It is the definition of a constructor for the class MessageIOGateway,
it takes an argument how the outgoing message should be encoded.
All pointer data members are initialized with 0. 

If compression is enabled (i.e., MUSCLE_ENABLE_ZLIB_ENCODING is defined)
MessageIOGateway has additional data members for the outgoing and
incoming codec to use.

Stephan Brnimann
 XXXX@XXXXX.COM 
      Open source rating and billing engine for communication networks.

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