Erpsystem Development Tutorial 04 Framework Module Management

Learned from the demo program,

In the framework main program engineering file, forms are replaced with Utangramframework,

Each module has a tmodule subclass and a getmoduleclass export function

So how does the framework manage the modules?

Let's start with the module.

UnitDlloneplugin;Interfaceusessysutils,classes,utangrammodule,sysmodule,regintf; Type Tusermodule=Class (tmodule)Private    PublicConstructor Create;Override; destructor Destroy; Override; procedureInit;Override; procedureFinalOverride; procedureNotify (Flags:integer; Intf:iinterface);Override; class procedureRegistermodule (Reg:iregistry);Override; class procedureUnregistermodule (Reg:iregistry);Override; End;ImplementationinitializationRegistermoduleclass (tusermodule);FinalizationEnd.

This is the Tmodule subclass of the module, thecode below initialization is executed first , so let's take a look at the registermoduleclass function on the Utangrammodule.pas

UnitUtangrammodule;{$weakpackageunit on}InterfaceusesSysutils,regintf,sysmodule;procedureInstallmodule (reg:iregistry);procedureUninstallmodule (reg:iregistry);functionGetmoduleclass:tmoduleclass; Exports Installmodule, Uninstallmodule, Getmoduleclass;ImplementationvarFmoduleclass:tmoduleclass;procedureRegistermoduleclass (moduleclass:tmoduleclass);beginFmoduleclass:=Moduleclass;End;functionGetmoduleclass:tmoduleclass;beginResult:=Fmoduleclass;End;End.

Registermoduleclass (tusermodule); in fact, the Tmodule subclass in the module is saved to a class reference variable fmoduleclass;

The exported function Getmoduleclass returns the fmoduleclass, so the Tmodule subclass of the module can be obtained by exporting the function Getmoduleclass

Next we look at the main program

Forms is replaced with Utangramframework, and a Application object is defined in the Utangramframework file, which means

Program HOST; uses   utangramframework,  in'mainform.pas' {  Frmmain}; {$R *.res} begin   application.initialize;  Application.mainformontaskbar:= True;  Application.createform (Tfrmmain, frmmain);  Application.Run; End.

The Application object here is actually defined by Utangramframework.

Unit Utangramframeworkttangramapp=Classvar  Application:ttangramapp; initialization   application:=ttangramapp.create; Finalization   Application.free;

In this way, the application object defined by the framework is created at the beginning of the program, and then we start with this line of code and debug to see how the module is managed

First enter the Tangramapp constructor

The floadmodulefromregistry here is Ttangramapp's Loadmodulefromregistry property variable, and the Set framework defaults to module loading from XML

The Fmodulemgr is a Tmodulemgr object, which is responsible for the management of the module, and the constructor of the module management class.

This creates a TObjectList object that is used to save the list of modules.

Tsingletonfactory.create (Iregistry, @CreateRegObj); Several lines are the creation of a class factory, which is described in detail in the interface management.

Continue, when all the units that contain the initialization section are executed, the program entry

Enter these functions to see

As can be seen, in fact, Ttangramapp just a few of the same name function, the actual call or to the Application object of forms, so that the winner program before starting to have the opportunity to do some initialization work

Next run to the Run function

Floadmodulefromregistry is set to true in the constructor, and we have not modified this property, so here we begin to load the module automatically.

This calls the module management class Tmodulemgr object Fmodumgr for module loading, into Loadmodules

The Getmodulelist function is responsible for reading the module file path that needs to be loaded automatically from the XML file and saving it to alist

This first determines if the file exists, and if it exists, it is ready to load

This creates a Ttangrammodule object based on the module's file, which is responsible for loading the module

This determines the type of the module and then loads it, after the load is completed

 @GetModuleClassPro: = GetProcAddress (Fmodulehandle,   getmoduleclass   " );  if  Assigned (getmoduleclasspro) then  begin   fmodulecls:  =getmoduleclasspro;    Fvalidmodule:  =fmodulecls<>nil  ;  if  (Fmodulecls<>nil ) " Span style= "color: #0000ff;"      >and  (createmoduleobjinstance) then    Fmoduleobj:  =fmodulecls.create;  end ; 

Get the module's export function Getmoduleclass, if this function is saved and called, save the return value to Fmodulecls, this fmodulecls save is the Tmodule subclass in the module, and create the object

procedureTmodulemgr.loadmodulefromfile (ConstModulefile:string);varModule:ttangrammodule;begin  TryModule:=ttangrammodule.create (modulefile,self.    Floadbatch);  if module.isvalidmodule  then fmodulelist.add (Module) ElseModule.free; Except on E:exception Do    beginwriteerrfmt (Err_loadmodule, [Extractfilename (Modulefile), e.message]); End; End;End;

If it is a valid module, it is added to the object list Fmodulelist

procedure Ttangramapp.run; begin  if  then  begin     fmodulemgr.loadmodules;    fmodulemgr.init;    End ;  Forms.Application.Run;  fmodulemgr.final; End;

When all modules are loaded, start module initialization

This takes out the Module object list fmodulelist each object in the initialization

Notice here that the fmoduleobj.init fmoduleobj is a Tmodule object, which is the object created by the Tmodule subclass in the Getmoduleclass return module when the module is loaded.

While Init is a virtual function in Tmodule, the actual call here is actually the INIT function implemented by the Tmodule subclass in the module.

When all modules are initialized, enter the message loop until the main form exits, calling the module's terminating function

procedure Ttangramapp.run; begin  if  then  begin     fmodulemgr.loadmodules;    Fmodulemgr.init;   End ;  Forms.Application.Run;  fmodulemgr.final; End;

Tmodulemgr provides two interface Imoduleloader,imoduleinstall for developers to customize module loading and installation

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Erpsystem Development Tutorial 04 Framework Module Management