我想知道当要访问的属性嵌套在另一个属性中时,从 Delphi 访问后期绑定属性或方法的正确方法是什么。让我解释。
检查此示例应用程序以检查防火墙是否处于活动状态,声明的 3 个函数使用HNetCfg.FwMgr
COM 对象并返回相同的值。
{$APPTYPE CONSOLE}
uses
Variants,
ActiveX,
Comobj,
SysUtils;
//in this function i don't use any "helper" property to hold the temp value of the properties.
function FirewallIsActive1 : Boolean;
var
Firewall : OleVariant;
begin
Firewall := CreateOleObject('HNetCfg.FwMgr');
Result := Firewall.LocalPolicy.CurrentProfile.FirewallEnabled;
end;
//here i hold the value of the LocalPolicy property
function FirewallIsActive2 : Boolean;
var
Firewall : OleVariant;
Policy : OleVariant;
begin
Firewall := CreateOleObject('HNetCfg.FwMgr');
Policy := Firewall.LocalPolicy;
Result := Policy.CurrentProfile.FirewallEnabled;
end;
//Here i use a "helper" variable for each property
function FirewallIsActive3 : Boolean;
var
Firewall : OleVariant;
Policy : OleVariant;
Profile : OleVariant;
begin
Firewall := CreateOleObject('HNetCfg.FwMgr');
Policy := Firewall.LocalPolicy;
Profile := Policy.CurrentProfile;
Result := Profile.FirewallEnabled;
end;
var
i : Integer;
begin
try
CoInitialize(nil);
try
Writeln(BoolToStr(FirewallIsActive1,True));
Writeln(BoolToStr(FirewallIsActive2,True));
Writeln(BoolToStr(FirewallIsActive3,True));
Readln;
finally
CoUninitialize;
end;
except
on E:Exception do
begin
Writeln(E.Classname, ':', E.Message);
Readln;
end;
end;
end.
我问这个问题是因为我想知道 Delphi 编译器是否能够生成代码以在 3 个函数的任何情况下处理 olevariants?