初始化部分不被调用 [英] The initialization part is not called

问题描述

我正在为Delphi和C ++ Builder维护VirtualTreeView组件.使用Delphi，一切都很好，但是当我使用C ++ Builder编译软件包时，不会调用Delphi单元中初始化部分中的代码.有什么想法吗?

I'm maintaining the VirtualTreeView component for Delphi and C++Builder. With Delphi everything is okay but when I compile the packages with the C++Builder the code in the initialization part in the Delphi units is not called. Any ideas?

推荐答案

在C ++ Builder项目中未调用Delphi单元的initialization/finalization部分时，通常意味着未在使用Delphi单元链接到最终可执行文件中，通常是因为C ++代码没有直接引用该单元中的任何代码，所以它得到了优化.与删除Delphi相比，C ++ Builder在删除未使用的代码方面更具侵略性.在Delphi中，只需在uses子句中添加一个单元就可以将该单元链接到.在C ++中不是这种情况.如果C ++代码未使用.hpp文件中的任何内容，则用C ++代码#include用Delphi单元的.hpp文件不足以保证已链接该单元.

When a Delphi unit's initialization/finalization sections are not being called in a C++Builder project, it usually means the Delphi unit is not being linked into the final executable, typically because the C++ code is not directly referencing any code in the unit, so it gets optimized out. C++Builder is a bit more aggressive about removing unused code than Delphi is. In Delp simply adding a unit to a uses clause forces that unit to be linked to. That is not the case in C++. #includeing a Delphi unit's .hpp file in C++ code is not enough to guarantee the unit is linked to, if the C++ code does not use anything from the .hpp file.

Indy在多个单元中都遇到了此问题，最显着的是IdAllAuthentications，IdAllFTPListParsers和IdAllHeaderCoders.这些单元都只包含初始化/完成代码，没有接口代码，因此它们生成的.hpp文件基本上是空的.为了强制链接，我必须在interface部分中添加{$HPPEMIT}语句，以在生成的.hpp文件中输出#pragma link语句.例如:

Indy ran into this problem in several of its units, most notably IdAllAuthentications, IdAllFTPListParsers, and IdAllHeaderCoders. These units all contain only initialization/finalization code, no interface code, so their generated .hpp files were basically empty. To force linkage, I had to add {$HPPEMIT} statements to the interface section to output #pragma link statements in the generated .hpp files. For example:

unit IdAllAuthentications;

interface

{
Note that this unit is simply for listing ALL Authentications in Indy.
The user could then add this unit to a uses clause in their program and
have all Authentications linked into their program.

ABSOLUTELY NO CODE is permitted in this unit.

}

{$I IdCompilerDefines.inc}

// RLebeau 2/14/09: this forces C++Builder to link to this unit so
// the units can register themselves correctly at program startup...

{$IFDEF HAS_DIRECTIVE_HPPEMIT_LINKUNIT}
  {$HPPEMIT LINKUNIT}
{$ELSE}
  {$HPPEMIT '#pragma link "IdAllAuthentications"'}
{$ENDIF}

implementation

// uses units that self-register in their initialization sections ...

end.

{$HPPEMIT LINKUNIT} 在XE5 Update 2中引入，以帮助链接使用单位作用域名称的单位:

{$HPPEMIT LINKUNIT} was introduced in XE5 Update 2, to help with linking units that use unit-scope names:

新增功能:现在，您可以使用HPPEMIT Delphi编译器指令来链接和生成C ++名称空间声明.

New: You can now use HPPEMIT Delphi compiler directives for linking and generating C++ namespace declarations.

...

{$ HPPEMIT LINKUNIT} 替换了iOS设备目标平台的#pragma链接. 有关更多信息，请参见HPPEMIT.

{$HPPEMIT LINKUNIT} replaces #pragma link for the iOS device target platform. For more information, see HPPEMIT.

对于C ++应用程序，{$HPPEMIT LINKUNIT}替换了移动平台上的#pragma link.

For C++ applications, {$HPPEMIT LINKUNIT} replaces #pragma link on mobile platforms.

Delphi运行时具有必须链接的单元才能启用某些功能.在C ++中，以前使用以下指令实现了自动链接:

The Delphi run time has units that must be linked in order to enable some functionality. In C++, auto-linking was previously achieved using the following directive:

{$HPPEMIT '#pragma link "<unitname>"'}

现在您应该改为使用以下指令:

Now you should use the following directive instead:

{$HPPEMIT LINKUNIT}

LINKUNIT生成一个#pragma link语句，该语句使用正确的修饰/命名间隔的单元名称来引用调用单元.

LINKUNIT generates a #pragma link statement that references the calling unit using the correct decorated/namespaced unit name.

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