枚举局部变量
重要
在 Visual Studio 2015 中，这种实现表达式计算器的方法已弃用。 有关实现 CLR 表达式计算器的信息，请参阅 CLR 表达式计算器和托管表达式计算器示例。
当 Visual Studio 准备好填充局部变量窗口时，它会在从 GetMethodProperty 返回的 IDebugProperty2 对象上调用 EnumChildren（请参阅实现 GetMethodProperty）。 IDebugProperty2::EnumChildren返回 IEnumDebugPropertyInfo2 对象。
IDebugProperty2::EnumChildren实现执行以下任务：
确保这是表示方法。
guidFilter使用参数确定对 IDebugMethodField 对象调用的方法。 如果guidFilter等于：guidFilterLocals，调用 EnumLocals 以获取 IEnumDebugFields 对象。guidFilterArgs，调用 EnumArguments 以获取对象IEnumDebugFields。guidFilterLocalsPlusArgs，合成一个枚举，该枚举将结果与结果IDebugMethodField::EnumLocals组合在一起IDebugMethodField::EnumArguments。 此合成由类CEnumMethodField表示。
实例化实现接口并包含
IEnumDebugFields对象的类（在此示例中IEnumDebugPropertyInfo2调用CEnumPropertyInfo）。从
IEnumDebugProperty2Info2对象返回CEnumPropertyInfo接口。
托管代码
此示例演示托管代码的 IDebugProperty2::EnumChildren 实现。
namespace EEMC
{
public class CFieldProperty : IDebugProperty2
{
public HRESULT EnumChildren (
uint dwFields,
uint radix,
ref Guid guidFilter,
ulong attribFilter,
string nameFilter,
uint timeout,
out IEnumDebugPropertyInfo2 properties)
{
properties = null;
IEnumDebugFields fields = null;
// If this field is a method...
if (0 != ((uint) fieldKind & (uint) FIELD_KIND.FIELD_TYPE_METHOD))
{
IDebugMethodField methodField = (IDebugMethodField) field;
// Enumerate parameters.
if (guidFilter == FilterGuids.guidFilterArgs)
{
methodField.EnumParameters(out fields);
}
// Enumerate local variables.
else if (guidFilter == FilterGuids.guidFilterLocals)
{
methodField.EnumLocals(address, out fields);
}
// Enumerate all local variables, including invisible compiler temps.
else if (guidFilter == FilterGuids.guidFilterAllLocals)
{
methodField.EnumAllLocals(address, out fields);
}
// Enumerate "this", if any, and all parameters and local variables.
else if (guidFilter == FilterGuids.guidFilterLocalsPlusArgs)
{
IDebugClassField fieldThis = null;
IEnumDebugFields parameters = null;
IEnumDebugFields locals = null;
methodField.GetThis(out fieldThis);
methodField.EnumParameters(out parameters);
methodField.EnumLocals(address, out locals);
CEnumMethodField enumMethodField =
new CEnumMethodField(fieldThis, parameters, locals);
fields = (IEnumDebugFields) enumMethodField;
}
// Enumerate only "this".
else if (guidFilter == FilterGuids.guidFilterThis)
{
IDebugClassField fieldThis = null;
methodField.GetThis(out fieldThis);
CEnumMethodField enumMethodField =
new CEnumMethodField(fieldThis, null, null);
fields = (IEnumDebugFields) enumMethodField;
}
else throw new COMException();// E_FAIL
}
// Wrap a property enumerator around the field enumerator.
CEnumPropertyInfo propertiesInfo =
new CEnumPropertyInfo(provider, address, binder, radix, fields,
(DEBUGPROP_INFO_FLAGS) dwFields);
properties = (IEnumDebugPropertyInfo2) propertiesInfo;
return COM.S_OK;
}
}
}
非托管代码
此示例演示非托管代码中的实现 IDebugProperty2::EnumChildren 。
STDMETHODIMP CFieldProperty::EnumChildren(
in DEBUGPROP_INFO_FLAGS infoFlags,
in DWORD radix,
in REFGUID guidFilter,
in DBG_ATTRIB_FLAGS attribFilter,
in LPCOLESTR pszNameFilter,
in DWORD timeout,
out IEnumDebugPropertyInfo2 ** ppchildren )
{
if (ppchildren == NULL)
return E_INVALIDARG;
else
*ppchildren = 0;
//get enumeration
HRESULT hr;
IEnumDebugFields* pfields = NULL;
if (m_fieldKind & FIELD_TYPE_METHOD)
{
//-----------------------------------------------------
// A Method
IDebugMethodField* pmethod = NULL;
//enumerate the requested properties
hr = m_field->QueryInterface( IID_IDebugMethodField,
reinterpret_cast<void**>(&pmethod) );
if (FAILED(hr))
return hr;
if (guidFilter == guidFilterArgs)
{
hr = pmethod->EnumParameters( &pfields );
}
else if (guidFilter == guidFilterLocals)
{
hr = pmethod->EnumLocals( m_address, &pfields );
}
else if (guidFilter == guidFilterAllLocals)
{
hr = pmethod->EnumAllLocals( m_address, &pfields );
}
else if (guidFilter == guidFilterLocalsPlusArgs)
{
//we create a special enumerator for this
IDebugClassField* pfieldThis = NULL;
IEnumDebugFields* pparameters = NULL;
IEnumDebugFields* plocals = NULL;
pmethod->GetThis( &pfieldThis );
pmethod->EnumParameters( &pparameters );
pmethod->EnumLocals( m_address, &plocals );
CEnumMethodField* penumMethodField =
new CEnumMethodField( pfieldThis, pparameters, plocals );
if (pfieldThis != NULL)
pfieldThis->Release();
if (pparameters != NULL)
pparameters->Release();
if (plocals != NULL)
plocals->Release();
if (!penumMethodField)
{
hr = E_OUTOFMEMORY;
}
else
{
hr = penumMethodField->QueryInterface( IID_IEnumDebugFields,
reinterpret_cast<void**>(&pfields) );
penumMethodField->Release();
}
}
else if (guidFilter == guidFilterThis )
{
IDebugClassField* pfieldThis = NULL;
hr = pmethod->GetThis( &pfieldThis );
if (SUCCEEDED(hr))
{
CEnumMethodField* penumMethodField =
new CEnumMethodField( pfieldThis, NULL, NULL );
pfieldThis->Release();
if (!penumMethodField)
{
hr = E_OUTOFMEMORY;
}
else
{
hr = penumMethodField->QueryInterface( IID_IEnumDebugFields,
reinterpret_cast<void**>(&pfields) );
penumMethodField->Release();
}
}
}
else
{
hr = E_FAIL;
}
pmethod->Release();
if (hr != S_OK)
return hr;
}
//create a property info enumeration around the field enumerator
CEnumPropertyInfo* pproperties =
new CEnumPropertyInfo( m_provider, m_address, m_binder,
radix, pfields, infoFlags );
if (pfields != NULL)
pfields->Release();
if (pproperties == NULL)
return E_OUTOFMEMORY;
hr = pproperties->QueryInterface( IID_IEnumDebugPropertyInfo2,
reinterpret_cast<void**>(ppchildren) );
pproperties->Release();
return hr;
}