ns3::OutputStreamWrapper Class Reference

A class encapsulating an output stream. More...

#include "output-stream-wrapper.h"

Inheritance diagram for ns3::OutputStreamWrapper:

Collaboration diagram for ns3::OutputStreamWrapper:

Public Member Functions
	OutputStreamWrapper (std::ostream *os)
	Constructor.
	OutputStreamWrapper (std::string filename, std::ios::openmode filemode)
	Constructor.
	~OutputStreamWrapper ()
std::ostream *	GetStream ()
	Return a pointer to an ostream previously set in the wrapper.
Public Member Functions inherited from ns3::SimpleRefCount< OutputStreamWrapper >
	SimpleRefCount ()
	Default constructor.
	SimpleRefCount (const SimpleRefCount &o)
	Copy constructor.
uint32_t	GetReferenceCount () const
	Get the reference count of the object.
SimpleRefCount &	operator= (const SimpleRefCount &o)
	Assignment operator.
void	Ref () const
	Increment the reference count.
void	Unref () const
	Decrement the reference count.

Private Attributes
bool	m_destroyable
	Can be destroyed.
std::ostream *	m_ostream
	The output stream.

Detailed Description

A class encapsulating an output stream.

This class wraps a pointer to a C++ std::ostream and provides reference counting of the object. This class is recommended for users who want to pass output streams in the ns-3 APIs, such as in callbacks or tracing.

This class is motivated by the fact that in C++, copy and assignment of iostreams is forbidden by std::basic_ios<>, because it is not possible to predict the semantics of the stream desired by a user.

When writing traced information to a file, the tempting ns-3 idiom is to create a bound callback with an ofstream as the bound object. Unfortunately, this implies a copy construction in order to get the ofstream object into the callback. This operation, as mentioned above, is forbidden by the STL. Using this class in ns-3 APIs is generally preferable to passing global pointers to ostream objects, or passing a pointer to a stack allocated ostream (which creates object lifetime issues).

One could imagine having this object inherit from stream to get the various overloaded operator<< defined, but we're going to be using a Ptr<OutputStreamWrapper> when passing this object around. In this case, the Ptr<> wouldn't understand the operators and we would have to dereference it to access the underlying object methods. Since we would have to dereference the Ptr<>, we don't bother and just expect the user to Get a saved pointer to an ostream and dereference it him or herself. As in:

void
TraceSink(Ptr<OutputStreamWrapper> streamWrapper, Ptr<const Packet> packet)
{
    std::ostream *stream = streamWrapper->GetStream();
    *stream << "got packet" << std::endl;
}

This class uses a basic ns-3 reference counting base class but is not an ns3::Object with attributes, TypeId, or aggregation.

Definition at line 60 of file output-stream-wrapper.h.

Constructor & Destructor Documentation

OutputStreamWrapper() [1/2]

ns3::OutputStreamWrapper::OutputStreamWrapper	(	std::string	filename,
		std::ios::openmode	filemode )

Constructor.

Parameters

filename	file name
filemode	std::ios::openmode flags

Definition at line 20 of file output-stream-wrapper.cc.

References m_ostream, NS_ABORT_MSG_UNLESS, NS_LOG_FUNCTION, and ns3::FatalImpl::RegisterStream().

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OutputStreamWrapper() [2/2]

ns3::OutputStreamWrapper::OutputStreamWrapper

(

std::ostream *

os

)

Constructor.

Parameters

os	output stream

Definition at line 33 of file output-stream-wrapper.cc.

References m_ostream, NS_ABORT_MSG_UNLESS, NS_LOG_FUNCTION, and ns3::FatalImpl::RegisterStream().

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~OutputStreamWrapper()

ns3::OutputStreamWrapper::~OutputStreamWrapper

(

)

Definition at line 42 of file output-stream-wrapper.cc.

References m_destroyable, m_ostream, NS_LOG_FUNCTION, and ns3::FatalImpl::UnregisterStream().

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Member Function Documentation

GetStream()

std::ostream * ns3::OutputStreamWrapper::GetStream

(

)

Return a pointer to an ostream previously set in the wrapper.

See also

SetStream

Returns

a pointer to the encapsulated std::ostream

Definition at line 54 of file output-stream-wrapper.cc.

References m_ostream, and NS_LOG_FUNCTION.

Member Data Documentation

m_destroyable

bool ns3::OutputStreamWrapper::m_destroyable

private

Can be destroyed.

Definition at line 87 of file output-stream-wrapper.h.

Referenced by ~OutputStreamWrapper().

m_ostream

std::ostream* ns3::OutputStreamWrapper::m_ostream

private

The output stream.

Definition at line 86 of file output-stream-wrapper.h.

Referenced by OutputStreamWrapper(), OutputStreamWrapper(), ~OutputStreamWrapper(), and GetStream().

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The documentation for this class was generated from the following files:

• src/network/utils/output-stream-wrapper.h
• src/network/utils/output-stream-wrapper.cc