将TopoDS_Face对象分配给其子对象编译没有错误，但我有 3 个 valgrind 错误

Assigning a TopoDS_Face object to its child object compiles with no errors but I have 3 valgrind errors

本文关键字：对象 valgrind 有错误 错误 编译 Face TopoDS 分配      更新时间：2023-10-16

我有一个名为Test的类，它继承了TopoDS_Face类。 已经从这个问题中获得了一些提示，但是...

// Test.h
class Test : public TopoDS_Face
{
public:
void operator = (const TopoDS_Face& base_)
{
TopoDS_Face::operator=(base_);
}
}
// testmain.cpp 
...
int main() {
//extract faces from IGES face
for (int i = 1; i <= nbs; i++) {
TopoDS_Shape shape = myIgesReader.Shape(i);
TopoDS_Face& face = static_cast<TopoDS_Face&>(TopoDS::Face(shape));
Test *test;
// tried each of these also and did not succeed
// Test *test = dynamic_cast<Test*>(&face);
// test = &face
test->TopoDS_Face::operator=(face);
...
}
}

main中的代码从 IGES 文件中提取面，并将每个面对象分配给在 main 中创建的测试对象。编译进行得很顺利，但 valgrind 抱怨以下错误：

==21718== Use of uninitialised value of size 8
==21718==    at 0x9B0946C: Handle_Standard_Transient::Assign(Standard_Transient const*) (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x408111: Handle_TopoDS_TShape::operator=(Handle_TopoDS_TShape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x409478: TopoDS_Shape::operator=(TopoDS_Shape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x4094CA: TopoDS_Face::operator=(TopoDS_Face const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x407273: main (in /home/ub/Projects/C++/test/test)
==21718== 
==21718== Use of uninitialised value of size 8
==21718==    at 0x9B09431: Handle_Standard_Transient::EndScope() (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x9B09475: Handle_Standard_Transient::Assign(Standard_Transient const*) (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x408111: Handle_TopoDS_TShape::operator=(Handle_TopoDS_TShape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x409478: TopoDS_Shape::operator=(TopoDS_Shape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x4094CA: TopoDS_Face::operator=(TopoDS_Face const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x407273: main (in /home/ub/Projects/C++/test/test)
==21718== 
==21718== Invalid read of size 4
==21718==    at 0x9B0943C: Handle_Standard_Transient::EndScope() (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x9B09475: Handle_Standard_Transient::Assign(Standard_Transient const*) (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x408111: Handle_TopoDS_TShape::operator=(Handle_TopoDS_TShape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x409478: TopoDS_Shape::operator=(TopoDS_Shape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x4094CA: TopoDS_Face::operator=(TopoDS_Face const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x407273: main (in /home/ub/Projects/C++/test/test)
==21718==  Address 0x75eb394801c38350 is not stack'd, malloc'd or (recently) free'd
==21718== 
==21718== 
==21718== Process terminating with default action of signal 11 (SIGSEGV)
==21718==  General Protection Fault
==21718==    at 0x9B0943C: Handle_Standard_Transient::EndScope() (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x9B09475: Handle_Standard_Transient::Assign(Standard_Transient const*) (in /usr/lib64/libTKernel.so.10.0.0)
==21718==    by 0x408111: Handle_TopoDS_TShape::operator=(Handle_TopoDS_TShape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x409478: TopoDS_Shape::operator=(TopoDS_Shape const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x4094CA: TopoDS_Face::operator=(TopoDS_Face const&) (in /home/ub/Projects/C++/test/test)
==21718==    by 0x407273: main (in /home/ub/Projects/C++/test/test)
==21718==

我需要帮助解决该程序。提前谢谢。

如果您查看TopoDS_Shape层次结构定义，您会注意到：

  • TopoDS_Shape不是接口(没有虚拟方法，也没有虚拟析构函数)。

  • TopoDS_Face、TopoDS_Shell 和其他人员提供来自TopoDS_Shape的"虚拟"继承，而无需添加任何字段或方法。

  • OCCT 不存储强类型的TopoDS_形状对象。OCCT 集合(首先包括TopoDS_Shape的子形状！)按值而不是引用存储TopoDS_Shape。像TopoDS：：Face() 这样的方法基本上会执行内存别名以返回强类型对象，并根据 TopoDS_Shape：：ShapeType() 方法返回的枚举进行运行时检查。

  • 实际上，可共享引用以TopoDS_Shape类的 Handle(TopoDS_TShape) 属性的形式存储。TopoDS_TShape是一个定义主形状数据(几何)的真实类，它确实是具有真实子类的虚拟类。

  • TopoDS_TShape层次结构(包含 TopoDS_TShape、TopoDS_TShell 等子类)是内部的和最终的 - 没有用于在应用程序级别扩展此层次结构的接口。我想说的是，在C++11期间，这些课程预计将被标记为最终课程。

基于此描述，应该清楚的是，更改TopoDS_Shape/TopoDS_TShape层次结构与OCCT设计(针对这些特定类)相矛盾，并且无法在应用程序级别可靠地完成。假定的替代方案是使用map(如NCollection_DataMap<TopoDS_Shape,TopTools_ShapeMapHasher,MyShapeProperties>)或文档结构(如XCAF文档定义具有TDataStd_NamedData和其他属性的装配结构)存储与形状相关的附加信息。

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