Delphi(Pascal)检查是否分配了每个字段

Question

我在Delphi中使用windows dll,我必须检查我的功能是否分配得很好.

我声明了函数类型,以便将我的dll函数放在类属性中,如下所示:

type
  MPOS_OpenResource = function (ResID: DWORD; CplNum:BYTE; BlockingMode: DWORD):WORD;stdcall;
  MPOS_CloseResource = function (ResID: DWORD; CplNum:BYTE):WORD;stdcall;
  MPOS_GetResourceID = function (CplNum : Byte; ResID : PDWord) : word;stdcall;
  ...

然后,我为我的dll类中的每个相应字段分配一个方法,如下所示:

@Self.m_MPOS_OpenResource := GetProcAddress( libHandler, '_MPOS_OpenResource@12' );
@Self.m_MPOS_CloseResource := GetProcAddress( libHandler, '_MPOS_CloseResource@8' );
@Self.m_MPOS_GetResourceID := GetProcAddress( libHandler, '_MPOS_GetResourceID@8');
...

我最后检查每个分配是否使用了一个巨大的if条款:

If(not Assigned(@m_MPOS_OpenResource) OR
  not Assigned(@m_MPOS_CloseResource) OR
  not Assigned(@m_MPOS_GetResourceID) OR 
...) then { Some code for exception}

我想避免if使用反射的giantic 子句,但我找不到有用的东西.我尝试了很多东西,最后一个开始:

for f in rttiType.GetFields() do 
  if(not Assigned(rttiType.GetField(f.Name).GetValue(Self)) 
      OR (Self.FieldAddress(f.Name) = Nil)) then begin
    ShowMessage('Field not assigned');
  end;
end;

但它不起作用.有人可以帮我吗？

Answer 1

您可以编写一个包装函数来执行测试:

procedure CheckedGetProcAddress(libHandle: HMODULE; const name: string; var proc: Pointer);
begin
  proc := GetProcAddress(libHandle, PChar(Name));
  if not Assigned(Proc) then
    raise EProcNotFound.Create(...);
end;

然后你写:

CheckedGetProcAddress(libHandler, '_MPOS_OpenResource@12', @@Self.m_MPOS_OpenResource);
CheckedGetProcAddress(libHandler, '_MPOS_CloseResource@8', @Self.m_MPOS_CloseResource);
CheckedGetProcAddress(libHandler, '_MPOS_GetResourceID@8', @Self.m_MPOS_GetResourceID);

FWIW,处理程序是错误的术语.这是一个模块句柄,因此应该命名您的变量libHandle.