TPluginHandler


class description - source file - inheritance tree

class TPluginHandler : public TObject

    private:
TPluginHandler() TPluginHandler(const char* base, const char* regexp, const char* className, const char* pluginName, const char* ctor) Bool_t CanHandle(const char* base, const char* uri) const char* GetBase() const const char* GetCtor() const const char* GetPlugin() const const char* GetRegexp() const void SetupCallEnv() public:
TPluginHandler(const TPluginHandler&) Int_t CheckPlugin() static TClass* Class() Long_t ExecPlugin(Int_t nargs) const char* GetClass() const virtual TClass* IsA() const Int_t LoadPlugin() virtual void ShowMembers(TMemberInspector& insp, char* parent) virtual void Streamer(TBuffer& b) void StreamerNVirtual(TBuffer& b)

Data Members

    private:
TString fBase base class which will be extended by plugin TString fRegexp regular expression which must be matched in URI TString fClass class to be loaded from plugin library TString fPlugin plugin library which should contain fClass TString fCtor ctor used to instantiate object of fClass TMethodCall* fCallEnv !ctor method call environment TFunction* fMethod !ctor method or global function Int_t fCanCall !if 1 fCallEnv is ok, -1 fCallEnv is not ok Bool_t fIsMacro plugin is a macro and not a library Bool_t fIsGlobal plugin ctor is a global function

Class Description

                                                                      
 TPluginManager                                                       
                                                                      
 This class implements a plugin library manager. It keeps track of    
 a list of plugin handlers. A plugin handler knows which plugin       
 library to load to get a specific class that is used to extend the   
 functionality of a specific base class and how to create an object   
 of this class. For example, to extend the base class TFile to be     
 able to read RFIO files one needs to load the plugin library         
 libRFIO.so which defines the TRFIOFile class. This loading should    
 be triggered when a given URI contains a regular expression defined  
 by the handler. Handlers can be defined for example as resources     
 in the .rootrc file, e.g.:                                           
                                                                      
   Plugin.TFile:       ^rfio:   TRFIOFile    RFIO   "<constructor>"   
   Plugin.TSQLServer:  ^mysql:  TMySQLServer MySQL  "<constructor>"   
   +Plugin.TSQLServer: ^pgsql:  TPgSQLServer PgSQL  "<constructor>"   
   Plugin.TVirtualFitter: *     TFitter      Minuit "TFitter(Int_t)"  
                                                                      
 Where the + in front of Plugin.TSQLServer says that it extends the   
 existing definition of TSQLServer, usefull when there is more than   
 one plugin that can extend the same base class. The "<constructor>"  
 should be the constructor or a static method that generates an       
 instance of the specified class. Global methods should start with    
 "::" in their name, like "::CreateFitter()".                         
 Instead of being a shared library a plugin can also be a CINT        
 script, so instead of libDialog.so one can have Dialog.C.            
 The * is a placeholder in case there is no need for a URI to         
 differentiate between different plugins for the same base class.     
 For the default plugins see $ROOTSYS/etc/system.rootrc.              
                                                                      
 Plugin handlers can also be registered at run time, e.g.:            
                                                                      
   gROOT->GetPluginManager()->AddHandler("TSQLServer", "^sapdb:",     
                                         "TSapDBServer", "SapDB",     
             "TSapDBServer(const char*,const char*, const char*)");   
                                                                      
 A list of currently defined handlers can be printed using:           
                                                                      
   gROOT->GetPluginManager()->Print(); // use option="a" to see ctors 
                                                                      
 The use of the plugin library manager removes all textual references 
 to hard-coded class and library names and the resulting dependencies 
 in the base classes. The plugin manager is used to extend a.o.       
 TFile, TSQLServer, TGrid, etc. functionality.                        
                                                                      


TPluginHandler(const char *base, const char *regexp, const char *className, const char *pluginName, const char *ctor)
 Create a plugin handler. Called by TPluginManager.

Bool_t CanHandle(const char *base, const char *uri)
 Check if regular expression appears in the URI, if so return kTRUE.
 If URI = 0 always return kTRUE.

void SetupCallEnv()
 Setup ctor or static method call environment.

Int_t CheckPlugin()
 Check if the plugin library for this handler exits. Returns 0
 when it exists and -1 in case the plugin does not exist.

Int_t LoadPlugin()
 Load the plugin library for this handler. Returns 0 on successful loading
 and -1 in case the library does not exist or in case of error.

Long_t ExecPlugin(Int_t va_(nargs), ...)
 Execute ctor for this plugin and return pointer to object of specific
 class. User must cast the returned long to the correct class.
 This method accepts a variable number of arguments to be passed
 to the ctor, where nargs is the number of arguments, followed
 by nargs arguments. Returns 0 in case of error.



Inline Functions


        TPluginHandler TPluginHandler(const char* base, const char* regexp, const char* className, const char* pluginName, const char* ctor)
           const char* GetBase() const
           const char* GetRegexp() const
           const char* GetPlugin() const
           const char* GetCtor() const
           const char* GetClass() const
               TClass* Class()
               TClass* IsA() const
                  void ShowMembers(TMemberInspector& insp, char* parent)
                  void Streamer(TBuffer& b)
                  void StreamerNVirtual(TBuffer& b)
        TPluginHandler TPluginHandler(const TPluginHandler&)


Author: Fons Rademakers 26/1/2002
Last update: root/base:$Name: $:$Id: TPluginManager.cxx,v 1.19 2003/05/15 20:01:30 brun Exp $
Copyright (C) 1995-2002, Rene Brun and Fons Rademakers. *


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