NSCL DAQ Software Documentation
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CIOInteractor

Name

CIOInteractor -- Separate prompt and input interactors.

Synopsis


#include <IOInteractor.h>
         
 class CIOInteractor {

  CIOInteractor(CInteractor& rInput, CInteractor& rOutput);

  virtual ~CIOInteractor();

  const CInteractor* getOutput();
  const CInteractor* getInput();
  virtual int Read(UInt_t nBytes, void* pBuffer);
  virtual int Write(UInt_t nBytes, void* pBuffer);
  virtual void Flush();
}

Description

This class models an interactor that is made up of a read-only and a write-only interactor. Prompt/written data goes to the write-only interactor while reads go to the read-only interactor. A sample usage would be for an interactive application where the output interactor would be a CFdInteractor connected to stdout, and the input interactor CFdInteractor connected to stdin

Note that this class has no copy constructor as it is not possible to ensure that all iteractor classes now and in the future will have copy constructors. In most cases, this is not a restriction.

Public member functions

CIOInteractor(CInteractor& rInput, CInteractor& rOutput);

Constructs the interactor, rInput is the interactor that will be used to get the input credentials. rOutput the interator to which prompts will be sent.

const CInteractor* getOutput();

Informational function that returns a pointer to the output interactor used to construct this object.

const CInteractor* getInput();

Informational function that returns a pointer to the input interactor used to construct this object.

virtual int Read(UInt_t nBytes, void* pBuffer);

Attempts to read nBytes from the input interactor into the buffer pointed to by pBuffer. The return value is determined by the type of the actual interactor, but generally is the actual number of bytes read. Usually a negative value indicates an error condition of some sort, and a zero indicates there is no data to be read, either because the end of the data source has been reached or because the input source is a non-blocking entity.

virtual int Write(UInt_t nBytes, void* pBuffer);

Writes nBytes of data from pBuffer to the output interactor. The return value depends on the actual interactor. Usually negative values indicate an error, zero usually indicates output to a non-blocking entity that is not able to accept output at that time, and values less than nBytes represent devices with some blocking/buffering factor that has been exceeded by the write.

virtual void Flush();

Flushes data in output buffes the output interactor may have.

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