ATL Collection Wizard

Sample Image

Introduction

One evening, tired of creating COM collections by hand, I created an object wizard to handle the grunt work for me. This wizard will implement the popular ICollectionOnSTLImpl interface, providing a few enhancements for a collection. The code this wizard writes was inspired by the book "ATL Internals" (Addison-Wesley Pub Co; ISBN: 0201695898). I trust what the authors in that book wrote and haven't stopped to try to understand it all. But nonetheless...on with the wizard.

Comments

Sample Image

You can choose which STL container your collection is based on, as well as the methods your collection will expose beyond the standard-issue methods provided by ICollectionOnSTLImpl. Typically, when I design collections I don't want the user to be able to create the collection themselves. Hence, the "non-creatable" and "unregistered" options. "Unregistered" will simply add the DECLARE_NO_REGISTRY to your collection's CoClass, but the "Non-creatable" option presented a real problem for me while writing this wizard. There is no method exposed by the ATL Object Wizard that allows me to add the proper OBJECT_ENTRY_NON_CREATEABLE macro to the object map. So, when this option is chosen, I throw a bogus value into the OBJECT_ENTRY macro to force a compile error. It is up to the developer to rectify the problem by inserting the proper macro. A cute message box will remind you of this when choosing this option.

Deficiencies

I didn't have time to create an install package for everyone to use, so the installation is manual but straight-forward. Simply copy everything but the *.dll into your "<DevStudioDirectory>\Common\MSDev98\Template\ATL" directory, and then copy and register the *.dll anywhere you'd like. Next time you run the ATL Object Wizard, you'll be able to create a collection based on what I've written.
Beneath all of the typedefs and Impls is the collection's workhorse, IEnumVARIANT. Some developers might wish to use a different IEnumXXX, so they'll have to alter the code manually.
This wizard doesn't support the stl::map container. It will in the future.
You MUST compile the IDL file at least once before using this wizard. This is because the wizard uses the project's typelib to discover the COM objects that the collection can contain.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

David Peterson

United States

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Vitaly Tomilov

7:24 3 May '10

>"Non-creatable" option presented a real problem for me while writing this wizard

All you had to do was to skip adding macro DECLARE_REGISTRY_RESOURCEID to the class declaration. There's nothing else to it.

As for the whole stuff in general, i have doubts, because implementation of ATL collection for simple types and interfaces are quite different from each other, i.e. it is one thing writing a COM collection of simple types, and totally different writing that for COM interfaces, i.e. the latter is way more complex/tricky.

Professional System Library on www.prosyslib.org

Fantastic Wizard... Just a couple of updates to the distribution file collection.h (changes in bold) For use at your own risk! ;-)

Parko

23:32 13 Apr '08



[!if=(FreeThreadedMarshaler, "TRUE")]

	[!set(NeedsGetControllingUnknown, "TRUE")]

[!endif]

// [!HeaderName] : Declaration of the [!ClassName]

[!crlf]

 

[!if=(FileExists, "FALSE")]

#ifndef __[!UpperShortName]_H_

#define __[!UpperShortName]_H_

[!crlf]

#include "resource.h"       // main symbols

[!else]

[!AddIncludeFile(TargetFile, "resource.h")]

[!endif]

[!crlf]

#include "[!COLLECTION_BASE][!COLLECTION_IMPL]Impl.h"

[!crlf]

 

typedef ICollectionOnSTLImpl<[!interfacename], &iid_[!interfacename]="">,

                             [!COLLECTION_IMPL]< CAdapt< CComPtr<[!COLLECTION_BASE]> > >,

                             [!COLLECTION_BASE]*,

                             _CopyItfFromAdaptItf<[!COLLECTION_BASE]>,

                             CComEnum[!COLLECTION_BASE]VariantOnSTL[!COLLECTION_IMPL]>

        [!InterfaceName]Impl;

 

/////////////////////////////////////////////////////////////////////////////

// [!ClassName]

 

class ATL_NO_VTABLE [!ClassName] : 

[!if=(ThreadingModel, "Single")]

	public CComObjectRootEx,

[!endif]

[!if=(ThreadingModel, "Apartment")]

	public CComObjectRootEx,

[!endif]

[!if=(ThreadingModel, "Both")]

	public CComObjectRootEx,

[!endif]

[!if=(ThreadingModel, "Free")]

	public CComObjectRootEx,

[!endif]

	public CComCoClass<[!ClassName], &CLSID_[!CoClassName]>,

[!if=(ErrorInfoEnabled, "TRUE")]

	public ISupportErrorInfo,

[!endif]

[!if=(ConnectionPointsEnabled, "TRUE")]

	public IConnectionPointContainerImpl<[!ClassName]>,

[!endif]

	public [!InterfaceName]Impl

{

public:

	[!ClassName]()

	{

[!if=(FreeThreadedMarshaler, "TRUE")]

		m_pUnkMarshaler = NULL;

[!endif]

	}

 

[!crlf]

[!if=(COLLECTION_UNREGISTERED,"TRUE")]

DECLARE_NO_REGISTRY()

[!else]

DECLARE_REGISTRY_RESOURCEID([!IDR_REGISTRYID])

[!endif]

 

[!if=(Aggregatable, "NO")]

DECLARE_NOT_AGGREGATABLE([!ClassName])

[!endif]

[!if=(Aggregatable, "ONLY")]

DECLARE_ONLY_AGGREGATABLE([!ClassName])

[!endif]

[!crlf]

DECLARE_PROTECT_FINAL_CONSTRUCT()

[!crlf]

BEGIN_COM_MAP([!ClassName])

	COM_INTERFACE_ENTRY([!InterfaceName])

[!if=(Dual, "TRUE")]

	COM_INTERFACE_ENTRY(IDispatch)

[!endif]

[!if=(ConnectionPointsEnabled, "TRUE")]

	COM_INTERFACE_ENTRY(IConnectionPointContainer)

[!endif]

[!if=(FreeThreadedMarshaler, "TRUE")]

	COM_INTERFACE_ENTRY_AGGREGATE(IID_IMarshal, m_pUnkMarshaler.p)

[!endif]

[!if=(ErrorInfoEnabled, "TRUE")]

	COM_INTERFACE_ENTRY(ISupportErrorInfo)

[!endif]

END_COM_MAP()

[!if=(ConnectionPointsEnabled, "TRUE")]

[!crlf]

BEGIN_CONNECTION_POINT_MAP([!ClassName])

END_CONNECTION_POINT_MAP()

[!endif]

 

[!if=(FreeThreadedMarshaler, "TRUE")]

[!crlf]

	HRESULT FinalConstruct()

	{

		return CoCreateFreeThreadedMarshaler(

			GetControllingUnknown(), &m_pUnkMarshaler.p);

	}

 

[!crlf]

	void FinalRelease()

	{

		m_pUnkMarshaler.Release();

	}

 

[!crlf]

	CComPtr m_pUnkMarshaler;

[!endif]

 

[!if=(ErrorInfoEnabled, "TRUE")]

[!crlf]

// ISupportsErrorInfo

	STDMETHOD(InterfaceSupportsErrorInfo)(REFIID riid);

[!endif]

[!crlf]

 

// [!InterfaceName]

public:

[!if=(COLLECTION_ADD,"TRUE")]

	STDMETHOD(Add)([!COLLECTION_BASE]* NewVal)

	{

		// check [in] parameter

		if(NewVal == NULL)

		{

			// invalid parameter

			return E_POINTER;

		}

		// add item to collection as a CComPtr object

		// to automatically increment the reference count

		m_coll.push_back(CComPtr<[!COLLECTION_BASE]>(NewVal));

		// all ok

		return S_OK;

	}

[!endif]

 

[!if=(COLLECTION_REMOVE,"TRUE")]

	STDMETHOD(Remove)(long Index, [!COLLECTION_BASE]** ppVal)

	{

		// check [out] parameter

		if(ppVal == NULL || *ppVal != NULL)

		{

			// invalid [out] parameter

			return E_POINTER;

		}

		// make sure Index is within valid range of collection

		if (Index < 1 || Index > m_coll.size())

		{

			// Index not in range!

			return S_FALSE;

		}

[!if=(COLLECTION_IMPL,"vector")]

		// update [out] parameter

		HRESULT hRes = m_coll[Index - 1].m_T.QueryInterface(ppVal);

		// check hRes

		if(hRes != S_OK)

		{

			// Query Interface failed!

			return E_NOINTERFACE;

		}

		// remove item from collection

		m_coll.erase(m_coll.begin() + Index - 1);

		// all ok

		return S_OK;

[!endif]

[!if=(COLLECTION_IMPL,"list")]

		// iterate through collection untill n'th item is found

		typedef [!COLLECTION_IMPL]< CAdapt< CComPtr<[!COLLECTION_BASE]> > >::iterator it;

		long Count(0);

		for ( it i = m_coll.begin(); i != m_coll.end(); i++,Count++ )

		{

			if ( Count == (Index - 1) )

			{

				// update [out] pointer

				HRESULT hRes = (*i).m_T.QueryInterface(ppVal);

				// check hRes

				if(hRes != S_OK)

				{

					// Query Interface failed!

					return E_NOINTERFACE;

				}

				// remove item from collection

				m_coll.erase(i);

				// all ok

				return S_OK;

			}

		}

		// weird error, Count NEVER equal to (Index -1)? Should

		// never happen because collection range is tested first!

		return E_INVALIDARG;

[!endif]

	}

[!endif]

};

 

[!crlf]

[!if=(FileExists, "FALSE")]

#endif //__[!UpperShortName]_H_

[!endif]

How to add outlook COM add-in

ramakrishnakadamati

18:09 13 Jun '07

Hi, I need a clarification regarding ATL COM object. Can i use ATL COM to create outlook plugin which needs to send data to web-server for authenticate user. If not how we can send data to web-server from outlook plugin.... Krishna
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Sorting?

Gary Chapman

23:17 16 Feb '07

Does anyone know a way to sort lists created by this wizard? I'd like to just call m_coll.sort() but I can't work out how to define the predicate comparison function. Any ideas? Thanks, Gary
Sign In·View Thread·Permalink	1.00/5 (1 vote)

Re: Sorting?

Dirty Highlander

5:38 14 May '07

This doesn't answer your question, but could be useful to people trying to sort a collection based on an STL vector. This isn't the most efficient way of doing this though, inserting the point into the collection at the correct point using a binary search would be better. This implementation is quick and nasty!

typedef CAdapt< CComPtr > IMyClassImpl;

class CMyCollection
{
public:
...

static bool compare(const IMyClassImpl & a, const IMyClassImpl & b)
{
float fXA, fXB;

a.m_T->get_x(&fXA);
b.m_T->get_x(&fXB);

return (fXA < fXB);
};

STDMETHOD(Add)(IMyClass* NewVal)
{
// add to the STL vector
m_coll.push_back(CComPtr(NewVal));

// sort points by x value
std::sort(m_coll.begin(), m_coll.end(), compare);

// everything is ok
return S_OK;
}

...
};

Excelent

Vider

23:32 6 Sep '06

Excelent, thank's for share...
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Re: Excelent

Portatofe

5:19 2 Oct '08

I think you are totally right here Cake Shop Cooking Dash Lost Secrets: Bermuda Triangle Cinema Tycoon 2: Movie Mania The Hidden Object Show: Season 2
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How to use the wizard with visual studio 7?

AverageJoe

22:43 11 May '06

Is there a way to use this wizard with visual stuido 7? thanks!
Sign In·View Thread·Permalink	1.00/5 (2 votes)

OLE Excel

Pham van hoi

1:12 13 Aug '05

how do insert OLE Excel into Visual Basic? Can you help me?
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MFC

sanpee

0:50 4 May '05

Is there any class in MFC to that implements ICollectionOnSTLImpl? I know how to mix ATL in MFC application, but just wonder if there is a class in MFC that will do the same trick.
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need help

Anonymous

22:46 27 Sep '04

can any one tell me how to compile the IDL file? and which IDL file should i compile in for this wizard
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Fantastic, Just what I needed!

Parko

0:55 19 Aug '04

Fantastic, certainly make my life easier!
Sign In·View Thread·Permalink	2.00/5 (1 vote)

Intellisense

qur

19:25 24 Feb '04

Wizard is working fine, but there is one problem intellisense stop to work whenever i create the collection using the wizard. --qur
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Great Job - One small problem

Mick O'Neill

18:41 23 Mar '03

The auto-generated Remove method, if selected, has an [out, retval] pointer for one of the members of the collection. This value is not referenced in the generated code. To return a reference to the removed object, and conform to the prototype, insert

(*i).m_T.QueryInterface(ppVal);

before

m_coll.erase(i);

Doing this before the erase on the STL collection object ensures the existance of a reference before the object is deleted.

Good Job!!!

BleuBleu

7:10 30 Jan '02

Thanks, your wizard will save me a lot of time! The code is nice too. Mat
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hmmm

savaisan

4:47 16 Dec '01

1. Selecting either list or vector disables the OK button. 2. Finishing the wizard without selecting container (see above) creates files and function declarations to IDL but not implementation what so ever. 3. Also there's a bug in the forward declaration section in .idl file. Regards, Sami
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Another small bug .. in COLLECTION.H

David Patrick

10:23 30 Oct '01

I noticed that no matter what options I chose for the "unregistered" checkbox the wizard was always placing the DECLARE_NO_REGISTRY() macro in my class.

Turns out the error is at line 60 of COLLECTION.H which was copied in the ..\Template\ATL directory.

The old line

[!if(COLLECTION_UNREGISTERED,"TRUE")]

The new line

[!if=(COLLECTION_UNREGISTERED,"TRUE")}

.. note the "=" after the if.

BTW .. as pointed out in the previous thread .. since explicitedly used "W" version of some apis this wizard will only work on NT systems .. just FYI.

Well, thanks for a great time saver

Small but serious bug

Pavlos Touboulidis

0:37 22 Aug '01

The wizard wasn't working for me too, so I debugged it and fixed it, instead of complaining;)

_CollectionDlg.cpp, in _LoadSupportedInterfaces
In the loop below, you need to cut the if (!bInterfacesArePresent){...} and put it after the loop.

for (long i = 0; i<lCount; i++)
{
	TYPEKIND TKind;
	if ( SUCCEEDED(spTypeLib->GetTypeInfoType(i,&TKind)) && (TKind == TKIND_INTERFACE || TKind == TKIND_DISPATCH))
	{
		bInterfacesArePresent = TRUE;
		CComBSTR bstrName;
		spTypeLib->GetDocumentation(i, &bstrName, NULL, NULL, NULL);
		::SendDlgItemMessageW(m_hWnd,ID, LB_ADDSTRING, 0,LPARAM(bstrName.m_str));
	}
//Cut from here
	if ( !bInterfacesArePresent )
	{
	       	MessageBox(_T("There are no interfaces declared in the TypeLib!  Can't use this wizard."),_T("Error"),MB_ICONERROR);
		return E_FAIL;
	}
//To here
}
//Paste here

Also, my system seemed to have some problems with the FindFirstFileW() and SendDlgItemMessageW() so I converted the BSTRs to ANSI and used the ANSI versions.

Don'n you think that, may be better to add "restricted" keyword in idl definition of _NewEnum?

Sergey Anisimov

4:21 1 Jun '01

But in other hand - it's good to
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How do I get COM objects into this collection ?

NicA

6:14 16 May '01

I'm new to COM and ATL and I'm trying to produce a simple component that will serve collections of other COM objects.

I've created my COM object, LoginUser and tested it with VB - all OK.

I've created my COM collection for LoginUser objects and tested it with VB - all OK.

What I am unable to do is add LoginUser object to the collection in VC++. I get the collection back with the correct number of items but all of the items appear to be uninitialised. Can anyone tell me how to do this. I've appended a snipet of my code in case anyone can tell me where I've gone astray and how to fix it.

STDMETHODIMP WASP::GetUsers( IWASPrecordset **pUser )
{
HRESULT hr;
IWASPrecordset *pR = NULL;

// Start COM subsystem
CoInitialize( NULL );

// Create a recordset object,
hr = CoCreateInstance ( CLSID_WASPrecordset,
NULL,
CLSCTX_INPROC_SERVER,
__uuidof(IWASPrecordset),
(void**) &pR );
// Did we succeed
if( SUCCEEDED(hr) )
{

for( i = 0; i < 10; ++i )
{
ILoginUserInt *pU = NULL;

// Create a LoginUser object,
hr = CoCreateInstance ( CLSID_LoginUserInt,
NULL,
CLSCTX_INPROC_SERVER,
__uuidof(ILoginUserInt),
(void**) &pU );

// Did we succeed - put user details into login user object
if( SUCCEEDED(hr) )
{
_bstr_t bst( "James" );

// Put user name into user object
pU->put_User( bst );

// Now put object into collection
pR->Add( pU );

// Release my copy of this object
pU->Release();
pU = NULL;
}
}

// Now set the return value to be the new object
pR->QueryInterface(__uuidof(IWASPrecordset),(void **) pUser);

// Release my copy of the object
pR->Release();

pR = NULL;
}

// Stop COM subsystem
::CoUninitialize();

return hr;
}

Thanks

Nic.

Re: How do I get COM objects into this collection ?

Tom Mason

23:39 24 May '01

2 things strike me about your code.
Firstly I, and the rest of the group I work with have come to realise that you should always use CComPtr's, (and CComVariant's and CComBSTR's) wherever possible. This leads onto my second observation. If you declare your collection as collection_type< CAdapt < CComPtr < IFoo > > > then when you add a member to it will automatically AddRef. I suspect that when release pU the reference count goes to zero and the instance of your object commits suicide.
Using CAdapt in your collection type prevents the CComPtr override of the & operator so it can be used safely in a collection. The advantage of using this is that if you call pR->release and the ATL collection goes through FinalRelease, when clear() is called on the collection, all the objects in your collection will automatically be Release()d

Tom Mason

Re: How do I get COM objects into this collection ?

NicA

23:49 28 May '01

Tom, I do have my collection declared as you describe list< CAdapt < CComPtr < ILoginUser > > >. I think you are correct about the suicide of my pU objects but I have not yet been able to discover why. Thanks for taking the time to look over my code. Nic.
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Re: How do I get COM objects into this collection ?

Tom Mason

0:33 29 May '01

Nic, Sorry my last didn't help. Have you tried putting message boxes, breakpoints or trace statement in the FinalRelease() method of your ILoginUser object? That is something I have done more than once to trace similar problems. Tom.
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Re: How do I get COM objects into this collection ?

Ivan14

2:20 10 Aug '01

I'v found a better way to do it. For example we have Users object that is a collection and User object. What we need is just to add several users to collection in constructor. This will show you how i made it:

typedef CComObject CUserObj;

CUsers::CUsers()
{
for(int i=0;i<10;i++){
CUserObj *usr;
CUserObj::CreateInstance(&usr);
CComBSTR a("aaa");
usr->m_bszName = a.Copy();;
IUser *pObj;
usr->QueryInterface(IID_IUser, (void**)&pObj);
Add(pObj);
}
}

Hope this will be useful to you.

Wizard support for stl::map container

Gerald Hackenberg

3:01 15 May '01

This wizard is a must have for ATL programmers! Especially since the Titan wizard from moretechnologies is no more available since 1998 and this kind of wizard is not yet integrated in VS.

In David Petersons documentation I read that "the stl::map container will be supported in the future". This is exactly what I still need. Will it be available and if yes, when? Or is there another wizard supporting this feature? Thanks, Gerald