Class to handle loadig of dynamic libraries. More...

#include <DynLib.h>

Public Member Functions
	DynLib (const std::string &library, const std::string &prefix=std::string(), const std::string &funcName=std::string(), bool closeOnDestruction=True)
	Load the dynamic library.
	DynLib (const std::string &library, Bool closeOnDestruction, const std::string &prefix="lib", const std::string &suffix=".so")
	Load the dynamic library with the given name, prefix, and suffix.
	~DynLib ()
	Close the dynamic library if told so in the constructor.
void *	getFunc (const std::string &funcName)
	Get a pointer to a function in the dynamic library.
void *	getHandle () const
	Get the dynamic library handle.
Private Member Functions
void	open (const std::string &name)
	Open (load)the dynamic library.
void	close ()
	Close (unload) the dynamic library (if opened).
Private Attributes
void *	itsHandle
Bool	itsDoClose

Detailed Description

Class to handle loadig of dynamic libraries.

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25

  <h3>Intended use:</h3> Public interface

 <h3>Prerequisite</h3><ul>     <li> Basic knowledge of the dlopen function family
 </ul>

  <h3>Synopsis</h3> 
  This class makes it possible to load a dynamic library and execute an
  initialization function. Furthermore one can get a pointer to any function
  in the dynamic library and close the library.

  It is a wrapper around functions dlopen, dlsym, and dlclose.

  If dlopen and so is not supported on a platform, the class acts as if
  the shared library could not be found.

  <h3>Example</h3> @anchor DynLib_example

         DynLib dl("bitflagsengine", "register_bitflagsengine");
         AlwaysAssert (dl.getHandle());

loads the executes library bitflagsengine and executes the given register initialization function.

Motivation

dlopen is a standard UNIX system call, but some operating systems do not support it or have different function names (notably Windows). In this way use of dynamic libraries is centralized and can easily b tailored as needed.

Definition at line 76 of file DynLib.h.

Constructor & Destructor Documentation

casa::DynLib::DynLib	(	const std::string &	library,
		const std::string &	prefix = `std::string()`,
		const std::string &	funcName = `std::string()`,
		bool	closeOnDestruction = `True`
	)

Load the dynamic library.

It is tried with prefixes "lib" and prefix and suffixes ".so" and ".dylib". If not loaded successfully, the internal handle is NULL.
If a non-empty funcName is given, that function is looked up and executed. Its signature must be void func(). Note that the function name should not be mangled, thus declared extern "C". An exception is thrown if the library is loaded successfully, but funcName could not be found.
If closeOnDestruction=True, the dynamic library is closed on destruction of the DynLib object.

casa::DynLib::DynLib	(	const std::string &	library,
		Bool	closeOnDestruction,
		const std::string &	prefix = `"lib"`,
		const std::string &	suffix = `".so"`
	)

Load the dynamic library with the given name, prefix, and suffix.

If not loaded successfully, the internal handle is NULL.
If closeOnDestruction=True, the dynamic library is closed when the DynLib object is destructed.

casa::DynLib::~DynLib ( )

Close the dynamic library if told so in the constructor.

Member Function Documentation

void casa::DynLib::close ( ) [private]

Close (unload) the dynamic library (if opened).

void* casa::DynLib::getFunc ( const std::string & funcName )

Get a pointer to a function in the dynamic library.

   The pointer has to be casted with a reinterpret_cast to a function
   pointer with the correct signature. When compiling with -pedantic the
   compiler will give a warning for such a cast, because on some systems
   (in particular some micro-controllers) a data pointer differs from a
   function pointer. However, that problem cannot be solved.
   For example:

          typedef Int MyFunc(Int, Int);
          void* initfunc = DynLib::getFunc (mod, ("register_"+name).c_str());
          if (initFunc) {
            MyFunc* func = reinterpret_cast<MyFunc*>(initfunc);
            Int result = func(1,2);
          }

casts to a function returning Int and taking two Ints.
A null pointer is returned if the function could not be found.

void* casa::DynLib::getHandle ( ) const [inline]

Get the dynamic library handle.

Definition at line 131 of file DynLib.h.

References itsHandle.

void casa::DynLib::open ( const std::string & name ) [private]

Open (load)the dynamic library.

Member Data Documentation

Bool casa::DynLib::itsDoClose [private]

Definition at line 144 of file DynLib.h.

void* casa::DynLib::itsHandle [private]

Definition at line 143 of file DynLib.h.

Referenced by getHandle().

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

casacore/casa/OS/DynLib.h

Public Member Functions