ATL / WTL / STL

Michael Dunn8-Jul-05 18:53

8-Jul-05 18:53

I did this in one of my apps:

// pWB2 is a IWebBrowser2* on the WebBrowser control hosed in my app
pWB2->ExecWB ( OLECMDID_COPY, OLECMDEXECOPT_DONTPROMPTUSER, NULL, NULL );

and it works without a hitch. I'm using a different interface than you, however.

--Mike--
Visual C++ MVP Cool | :cool:

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Melena11-Jul-05 5:59

Melena

11-Jul-05 5:59

Thanks Mike.

So you didn't have to enable anything to make the copy work? I've seen things like UIEnable function calls, so I'm wondering if that's what I'm missing.

Also, had you created your own menu which is run when the user right-clicks in the browser, or was it just using the IE engine right-click menu? I'm wondering how you knew when to execute the pWB2->ExecWB...

Thanks again,

Melena

Melena13-Jul-05 5:39

Melena

13-Jul-05 5:39

I've figured this problem out. Was using CoInitialize() instead of OleInitialize(). The OleInitialize() makes the clipboard available, once I started using that, the copy worked fine.

Michael Dunn14-Jul-05 2:59

Comparing STL containers of pointers

14-Jul-05 2:59

cool

--Mike--
Visual C++ MVP Cool | :cool:

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Rob Caldecott7-Jul-05 5:24

7-Jul-05 5:24

If I have an STL container that contains objects, then I can compare them easily - for example:

class CMyClass
{
int m_n;
CMyClass(int n) : m_n(n) { }

bool operator==(const CMyClass& o) const
{
// User defined comparison operator here
}
};

...

vector<CMyClass> v1;
vector<CMyClass> v2;
v1.push_back(CMyClass(1234));
v2.push_back(CMyClass(1234));

if (v1 == v2) // Calls CMyClass operator==

However, I often use containers of pointers, and when I do, comparing two containers doesn't call the objects operator== function. For example:

class CMyClass
{
int m_n;
CMyClass(int n) : m_n(n) { }

bool operator==(const CMyClass& o) const
{
// User defined comparison operator here
}
};

...

vector<CMyClass*> v1;
vector<CMyClass*> v2;
v1.push_back(new CMyClass(1234));
v2.push_back(new CMyClass(1234));

if (v1 == v2) // Simply compares the value of each pointer, so not much use!

My question is - are there any operators I can overload to make the comparison work for containers of pointers, or do I need to hand-roll my own comparison function? I hope this makes sense!

Re: Comparing STL containers of pointers

Rob Caldecott7-Jul-05 6:07

7-Jul-05 6:07

OK, after some experimenting I realised that std::equal can be passed a function object, so I now have something like this:

template <class T>
class EqualT
{
public:
	inline bool operator()(const T* t1, const T* t2) { return *t1 == *t2; }
};

...

vector<CMyClass*> v1;
vector<CMyClass*> v2;
...

if (equal(v1.begin(), v1.end(), v2.begin(), EqualT<CMyClass>()))
// The containers are equal

Using a function object template means I can compare containers containing other pointer type - the EqualT operator() handles the de-referencing. Nice.

Ooops...

Rob Caldecott7-Jul-05 6:33

Re: Comparing STL containers of pointers

7-Jul-05 6:33

I meant:

struct EqualT
{
template <class T>
inline bool operator()(const T* t1, const T* t2) const { return *t1 == *t2; }
};
...
vector<CMyClass*> v1;
vector<CMyClass*> v2;
...
if (equal(v1.begin(), v1.end(), v2.begin(), EqualT()))
// Equal!

Ooops...

Jörgen Sigvardsson7-Jul-05 9:56

Jörgen Sigvardsson

7-Jul-05 9:56

The power of STL, you have seen! Smile | :)

Good music: In my rosary[^]

Stuart Dootson8-Jul-05 7:45

Stuart Dootson

8-Jul-05 7:45

You could use boost::indirect_iterator[^] - then you don't need to do anything much (except use Boost!).

Of course, you're pulling a fair number of headers in, but who knows, you might find other parts of Boost you want to use...

Stuart Dootson

'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p'

Re: Comparing STL containers of pointers

Axter4-Aug-05 18:28

Axter

4-Aug-05 18:28

I recommend you use a smart pointer like the following:
http://code.axter.com/clone_ptr.h

The above smart pointer has operator==() functions that work on the object itself instead of the pointer.

Example code:

#include <iostream><br />
#include <list><br />
#include "clone_ptr.h"<br />
<br />
using namespace std;<br />
<br />
class A<br />
{<br />
public:<br />
	A(int a) : m_a(a) {}<br />
	virtual ~A() {}<br />
	virtual void Somefunction() const<br />
	{<br />
		cout << "I'm A " << m_a << endl;<br />
	}<br />
	bool operator==(const A& Src)const{return (m_a == Src.m_a);}<br />
	int m_a;<br />
};<br />
<br />
class B : public A<br />
{<br />
public:<br />
	B(int a) : A(a) {}<br />
	void Somefunction() const<br />
	{<br />
		cout << "I'm B " << m_a << endl;<br />
	}<br />
};<br />
<br />
class C : public A<br />
{<br />
public:<br />
	C(int a) : A(a) {}<br />
	void Somefunction() const<br />
	{<br />
		cout << "I'm C " << m_a << endl;<br />
	}<br />
};<br />
<br />
int main(int argc, char* argv[])<br />
{<br />
	list<clone_ptr<A> > MyListOfA_PtrsX;<br />
	MyListOfA_PtrsX.push_back(new A(1));<br />
	MyListOfA_PtrsX.push_back(new A(2));<br />
	MyListOfA_PtrsX.push_back(new A(3));<br />
	<br />
	list<clone_ptr<A> > MyListOfA_PtrsY;<br />
	MyListOfA_PtrsY.push_back(new B(4));<br />
	MyListOfA_PtrsY.push_back(new B(5));<br />
	MyListOfA_PtrsY.push_back(new B(6));<br />
	<br />
	list<clone_ptr<A> > MyListOfA_PtrsZ;<br />
	MyListOfA_PtrsZ.push_back(new C(1));<br />
	MyListOfA_PtrsZ.push_back(new C(2));<br />
	MyListOfA_PtrsZ.push_back(new C(3));<br />
<br />
	bool IsEqual1 = (MyListOfA_PtrsX == MyListOfA_PtrsY); //Should be false<br />
	bool IsEqual2 = (MyListOfA_PtrsX == MyListOfA_PtrsZ); //Should be true<br />
<br />
	cout << IsEqual1 << endl;<br />
	cout << IsEqual2 << endl;<br />
<br />
	system("pause");<br />
	return 0;<br />
}

Top ten member of C++ Expert Exchange.
http://www.experts-exchange.com/Cplusplus

dueto

Raudel6-Jul-05 5:49

Raudel

6-Jul-05 5:49

forgive me if my ask is not about the theme treated in this forum.
I am working in c++ builder 6.0, i am using the GetHeapStatus function to know the memory allocated by the application, but all the fields of the struct returned by the function are in 0, why can I do??
Thanks.

Initializing STL containers

Rob Caldecott6-Jul-05 5:22

6-Jul-05 5:22

I have a lot of places in my code where I am using a static const table that I then use for lookup purposes. For example:

static const struct
{
    LPCTSTR psz;
    UINT n;
} table[] =
{
    _T("Rob"), 1971,
    _T("Becky"), 1977,
};

...

for (int i = 0; i < sizeof(table) / sizeof(*table); i++)
{
    // Do something with a table element
    ...
}

This is all well and good, but now I am an STL fanatic I would rather using a static vector (so I can utilize find_if, for_each, etc.

My question - is there an elegant way to initialise a container whilst still making the whole thing const. For example, the following would be sweet:

class CMyData
{
public:
    LPCTSTR m_psz;
    UINT m_n;

    CMyData(LPCTSTR psz, UINT n) : m_psz(psz), m_n(n) { }
};

static const vector<CMyData> v =
{
    CMyData(_T("Rob"), 1971),
    CMyData(_T("Becky"), 1977),
};

The above doesn't work. No surprises. If instead I do something like this:

static const vector<CMyData> v;
if (v.empty())
{
    v.push_back(...); // ERROR
    v.push_back(...); // ERROR
}

The fact the vector is defined as 'const' means I can't add anything to it the first time the function is called. I guess I could instead do:

static vector<const CMyData> v;
if (v.empty())
{
    v.push_back(...);
    v.push_back(...);
}

The above works OK, but I wondered if any STL gurus had any other solutions?

Re: Initializing STL containers

Michael Dunn6-Jul-05 6:31

Re: Initializing STL containers

6-Jul-05 6:31

I don't see how making the container itself const would be useful. If you can't modify the vector, how can you add objects to it?
BTW check out boost::assign[^] for some neat classes that make STL container initialization nicer.

--Mike--
Visual C++ MVP Cool | :cool:

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Rob Caldecott6-Jul-05 6:39

Re: Initializing STL containers

6-Jul-05 6:39

Michael Dunn wrote:
I don't see how making the container itself const would be useful.

Because, like in my first static const struct example, I only want the container for lookups - I won't add anything to it once it has been initialized. Looks like I might have to check Boost out...

Rob Caldecott6-Jul-05 6:41

find_if and function objects ('functors')

6-Jul-05 6:41

Looks like the Boost 'list_of' function is exactly what I need!

e.g.:

static const vector<int> v = list_of(1)(2)(3)

Rob Caldecott5-Jul-05 3:11

5-Jul-05 3:11

Is there any way to use a function object with find_if instead of a predicate? Predicates have limited use, and it would be neat if I could do something like this:

struct findfunc
{
    CMyPtr* m_pData;
    findfunc(CMyPtr* p) : m_pData(p) { }
    bool operator()(CMyData* ptr)
    {
        return (ptr->blah == m_pData->blah);
    }
}

...

std::list<CMyData*> mylist;
...
CMyPtr somedata;
...
std::list<CMyData*>::iterator it = std::find_if(mylist.begin(), mylist.end(), findfunc(somedata));

Basically, I want to perform a more advanced search (on any STL container) than find_if currently allows. I am quite new to STL, so please bear with me!

Michael Dunn5-Jul-05 6:54

5-Jul-05 6:54

The code you posted should work fine. The functor trick lets you use an object (that defines operator() properly) in place of a function.

--Mike--
Visual C++ MVP Cool | :cool:

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Rob Caldecott5-Jul-05 22:48

5-Jul-05 22:48

You're right - it does work - I was having a blonde moment!

The STL rocks. I feel I have hardly scratched the surface yet already I am in awe of its capabilities...

Jörgen Sigvardsson5-Jul-05 12:37

Jörgen Sigvardsson

5-Jul-05 12:37

Don't forget to make operator() of your functors a const method. Otherwise it may not work, if your STL implementation passes the functor objects by const reference.

Good music: In my rosary[^]

Rob Caldecott6-Jul-05 0:21