Sky*_*ker 24 c++ python boost exception boost-python
我有以下两个C++异常的简单层次结构:
class LIB_EXP ClusterException : public std::exception {
public:
ClusterException() { }
ClusterException(const std::string& what) { init(what); }
virtual const char* what() const throw() { return what_.c_str(); }
virtual ~ClusterException() throw() {}
virtual ClusterException* clone() { return new ClusterException(*this); }
protected:
void init(const std::string& what) { what_ = what; }
private:
std::string what_;
};
class LIB_EXP ClusterExecutionException : public ClusterException {
public:
ClusterExecutionException(const std::string& jsonResponse);
std::string getErrorType() const throw() { return errorType_; }
std::string getClusterResponse() const throw() { return clusterResponse_; }
virtual ~ClusterExecutionException() throw() {}
virtual ClusterExecutionException* clone() { return new ClusterExecutionException(*this); }
private:
std::string errorType_;
std::string clusterResponse_;
};
然后我使用Boost-Python将它们导出到Python,如下所示.请注意我使用它bases来确保在转换中保留继承关系:
class_<ClusterException> clusterException("ClusterException", no_init);
clusterException.add_property("message", &ClusterException::what);
clusterExceptionType = clusterException.ptr();
register_exception_translator<ClusterException>(&translateClusterException);
class_<ClusterExecutionException, bases<ClusterException> > clusterExecutionException("ClusterExecutionException", no_init);
clusterExecutionException.add_property("message", &ClusterExecutionException::what)
.add_property("errorType", &ClusterExecutionException::getErrorType)
.add_property("clusterResponse", &ClusterExecutionException::getClusterResponse);
clusterExecutionExceptionType = clusterExecutionException.ptr();
register_exception_translator<ClusterExecutionException>(&translateClusterExecutionException);
然后是异常翻译方法:
static PyObject *clusterExceptionType = NULL;
static void translateClusterException(ClusterException const &exception) {
assert(clusterExceptionType != NULL);
boost::python::object pythonExceptionInstance(exception);
PyErr_SetObject(clusterExceptionType, pythonExceptionInstance.ptr());
}
static PyObject *clusterExecutionExceptionType = NULL;
static void translateClusterExecutionException(ClusterExecutionException const &exception) {
assert(clusterExecutionExceptionType != NULL);
boost::python::object pythonExceptionInstance(exception);
PyErr_SetObject(clusterExecutionExceptionType, pythonExceptionInstance.ptr());
}
我创建了以下测试C++函数,抛出异常:
static void boomTest(int exCase) {
switch (exCase) {
case 0: throw ClusterException("Connection to server failed");
break;
case 1: throw ClusterExecutionException("Error X while executing in the cluster");
break;
default: throw std::runtime_error("Unknown exception type");
}
}
最后调用我的C++的Python测试代码boomTest:
import cluster
reload(cluster)
from cluster import ClusterException, ClusterExecutionException
def test_exception(exCase):
try:
cluster.boomTest(exCase)
except ClusterException as ex:
print 'Success! ClusterException gracefully handled:' \
'\n message="%s"' % ex.message
except ClusterExecutionException as ex:
print 'Success! ClusterExecutionException gracefully handled:' \
'\n message="%s"' \
'\n errorType="%s"' \
'\n clusterResponse="%s"' % (ex.message, ex.errorType, ex.clusterResponse)
except:
print 'Caught unknown exception: %s "%s"' % (sys.exc_info()[0], sys.exc_info()[1])
def main():
print '\n************************ throwing ClusterException ***********************************************************************'
test_exception(0)
print '\n************************ throwing ClusterExecutionException **************************************************************'
test_exception(1)
print '\n************************ throwing std::runtime_error *********************************************************************'
test_exception(2)
if __name__ == "__main__":
main()
到这里一切都有效.但是,如果我ClusterExecutionException从Python中删除catch处理程序,则会捕获此异常并回退到未知异常,而不是作为其基础捕获ClusterException.
我已经在加速的Python尝试注册时的异常转换ClusterExecutionException将其注册为基地ClusterException,然后被逮住"多态",但那么它不会被抓到的ClusterExecutionException.怎样才能让这个ClusterExecutionException被逮住既ClusterException和ClusterExecutionException？我当然尝试将此ClusterExecutionException异常注册为两者ClusterException,ClusterExecutionException但它遵循最后一个胜利策略,并且只有一个不同时工作.
有没有其他方法可以解决这个问题？
更新1:这个问题的关键是要在C++端找到exceptPython语句的类型,例如except ClusterException as ex:在C++方面一旦未知.Boost.Python转换的异常将调用与异常的动态类型相对应的translate函数,并且Python catch静态类型未知.
更新2:正如建议将Python代码更改为以下即添加print(type(ex).__bases__)给出:
def test_exception(exCase):
try:
cluster.boomTest(exCase)
except ClusterException as ex:
print(type(ex).__bases__)
print 'Success! ClusterException gracefully handled:' \
'\n message="%s"' % ex.message
except ClusterExecutionException as ex:
print(type(ex).__bases__)
print 'Success! ClusterExecutionException gracefully handled:' \
'\n message="%s"' \
'\n errorType="%s"' \
'\n clusterResponse="%s"' % (ex.message, ex.errorType, ex.clusterResponse)
except:
print 'Caught unknown exception: %s "%s"' % (sys.exc_info()[0], sys.exc_info()[1])
和输出:
************************ throwing ClusterException ***********************************************************************
(<type 'Boost.Python.instance'>,)
Success! ClusterException gracefully handled:
message="Connection to server failed"
************************ throwing ClusterExecutionException **************************************************************
(<class 'cluster.ClusterException'>,)
Success! ClusterExecutionException gracefully handled:
message="Error X while executing in the cluster"
errorType="LifeCycleException"
clusterResponse="{ "resultStatus": "Error", "errorType": "LifeCycleException", "errorMessage": "Error X while executing in the cluster" }"
意味着继承关系是从Python"看到"的.但多态处理仍然无效.
更新3这是运行VS的输出dumpbin.exe:
我使用的命令是:
dumpbin.exe /EXPORTS /SYMBOLS C:\ClusterDK\x64\Debug\ClusterDK.dll > c:\temp\dumpbin.out
以及输出的相关部分:
Microsoft (R) COFF/PE Dumper Version 11.00.50727.1
Copyright (C) Microsoft Corporation. All rights reserved.
Dump of file C:\ClusterDK\x64\Debug\ClusterDK.dll
File Type: DLL
Section contains the following exports for ClusterDK.dll
00000000 characteristics
5A1689DA time date stamp Thu Nov 23 09:42:02 2017
0.00 version
1 ordinal base
78 number of functions
78 number of names
ordinal hint RVA name
8 7 00004485 ??0ClusterException@cluster@@QEAA@AEBV01@@Z = @ILT+13440(??0ClusterException@cluster@@QEAA@AEBV01@@Z)
9 8 00001659 ??0ClusterException@cluster@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z = @ILT+1620(??0ClusterException@cluster@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)
10 9 00001F1E ??0ClusterException@cluster@@QEAA@XZ = @ILT+3865(??0ClusterException@cluster@@QEAA@XZ)
11 A 00004D4F ??0ClusterExecutionException@cluster@@QEAA@AEBV01@@Z = @ILT+15690(??0ClusterExecutionException@cluster@@QEAA@AEBV01@@Z)
12 B 000010AA ??0ClusterExecutionException@cluster@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z = @ILT+165(??0ClusterExecutionException@cluster@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)
27 1A 000035D0 ??1ClusterException@cluster@@UEAA@XZ = @ILT+9675(??1ClusterException@cluster@@UEAA@XZ)
28 1B 00003C7E ??1ClusterExecutionException@cluster@@UEAA@XZ = @ILT+11385(??1ClusterExecutionException@cluster@@UEAA@XZ)
37 24 00002BD5 ??4ClusterException@cluster@@QEAAAEAV01@AEBV01@@Z = @ILT+7120(??4ClusterException@cluster@@QEAAAEAV01@AEBV01@@Z)
38 25 000034D1 ??4ClusterExecutionException@cluster@@QEAAAEAV01@AEBV01@@Z = @ILT+9420(??4ClusterExecutionException@cluster@@QEAAAEAV01@AEBV01@@Z)
46 2D 000D2220 ??_7ClusterException@cluster@@6B@ = ??_7ClusterException@cluster@@6B@ (const cluster::ClusterException::`vftable')
47 2E 000D2248 ??_7ClusterExecutionException@cluster@@6B@ = ??_7ClusterExecutionException@cluster@@6B@ (const cluster::ClusterExecutionException::`vftable')
52 33 00004BB5 ?clone@ClusterException@cluster@@UEAAPEAV12@XZ = @ILT+15280(?clone@ClusterException@cluster@@UEAAPEAV12@XZ)
53 34 00004D31 ?clone@ClusterExecutionException@cluster@@UEAAPEAV12@XZ = @ILT+15660(?clone@ClusterExecutionException@cluster@@UEAAPEAV12@XZ)
61 3C 00001D43 ?getErrorType@ClusterExecutionException@cluster@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ = @ILT+3390(?getErrorType@ClusterExecutionException@cluster@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)
69 44 0000480E ?init@ClusterException@cluster@@IEAAXAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z = @ILT+14345(?init@ClusterException@cluster@@IEAAXAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)
78 4D 000032FB ?what@ClusterException@cluster@@UEBAPEBDXZ = @ILT+8950(?what@ClusterException@cluster@@UEBAPEBDXZ)
Summary
4000 .data
5000 .idata
12000 .pdata
54000 .rdata
2000 .reloc
1000 .rsrc
C9000 .text
1000 .tls
我的Python技能很生疏，我还没有测试过这一点，所以这可能需要进一步改进，但尝试添加异常转换方法来处理基类异常类型：
static PyObject *clusterExecutionAsClusterExceptionType = NULL;
static void translateClusterExecutionAsClusterException(ClusterException const &exception) {
ClusterExecutionException* upcasted = dynamic_cast<ClusterExecutionException*>(&exception);
if (upcasted)
{
assert(clusterExecutionAsClusterExceptionType != NULL);
boost::python::object pythonExceptionInstance(*upcasted);
PyErr_SetObject(clusterExecutionAsClusterExceptionType, pythonExceptionInstance.ptr());
}
}
register_exception_translator<ClusterException>(&translateClusterExecutionAsClusterException);