c++.stlsoft - [COMSTL; Adi's report] stlsoft::interface_ptr is a zombie; use stlsoft::ref_ptr
- "Matthew" <matthew hat.stlsoft.dot.org> Dec 01 2006
- Adi Shavit <adish gentech.co.il> Dec 03 2006
- Adi Shavit <adish gentech.co.il> Dec 05 2006
- "Matthew" <matthew hat.stlsoft.dot.org> Dec 05 2006
- Adi Shavit <adish gentech.co.il> Dec 05 2006
Adi comstl::interface_ptr<> is obsolete. It offers nothing that stlsoft::ref_ptr<> does not; it actually offers less. I don't know why this component has continued to be available. I've just grepped all my sources and can find only a single use of it (which I've just changed). My apologies for having left it in there. The preferred approach is to use stlsoft::ref_ptr<>. Why? Because it facilitates forward declaration of a smart pointer specialisation. (I'm working on a small article to explain how/why, which I hope to publish - perhaps on CodeProject - soonish.) I'm changing comstl/smartptr/interface_ptr.hpp as we speak to issue a warning if included, and will redefine the class to be implemented in terms of stlsoft::ref_ptr<>. Sorry about that ... :$ Matthew And now to the next question ...
Dec 01 2006
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body dir="ltr" bgcolor="#ffffff" text="#000066"> <p style="margin-bottom: 0cm; margin-top: 0pt;"><font size="-1"><font face="Verdana">I wasn't even aware of ref_ptr.</font></font></p> <p style="margin-bottom: 0cm; margin-top: 0pt;"><span style="font-size: 13px;"><font face="Verdana">I'll try it and let you know how it goes.<br> </font></span><span style="font-size: 13px;"></span></p> <p style="margin-bottom: 0cm; margin-top: 0pt;"><span style="font-size: 13px;"><font face="Verdana">Adi</font></span><br> </p> <p style="margin-bottom: 0cm; margin-top: 0pt;"><span style="font-size: 13px;"></span><br> </p> <p style="margin-bottom: 0cm; margin-top: 0pt;"><span style="font-size: 13px;"></span></p> <p style="margin-bottom: 0cm; margin-top: 0pt;"><br> Matthew wrote:<br> </p> <blockquote cite="midekrbio$313n$1 digitaldaemon.com" type="cite"> <pre wrap="">Adi comstl::interface_ptr<> is obsolete. It offers nothing that stlsoft::ref_ptr<> does not; it actually offers less. I don't know why this component has continued to be available. I've just grepped all my sources and can find only a single use of it (which I've just changed). My apologies for having left it in there. The preferred approach is to use stlsoft::ref_ptr<>. Why? Because it facilitates forward declaration of a smart pointer specialisation. (I'm working on a small article to explain how/why, which I hope to publish - perhaps on CodeProject - soonish.) I'm changing comstl/smartptr/interface_ptr.hpp as we speak to issue a warning if included, and will redefine the class to be implemented in terms of stlsoft::ref_ptr<>. Sorry about that ... :$ Matthew And now to the next question ... </pre> </blockquote> </body> </html>
Dec 03 2006
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<font face="Verdana">I see that ref_ptr doesn't have a set() method.<br>
How can I implement the code I posted before:<br>
</font>
<blockquote><font face="Courier New, Courier,
monospace"> //
Create a source filter specified by filename<br>
interface_ptr<IBaseFilter> pSource; // The
interface_ptr<> object<br>
{<br>
IBaseFilter* ppSource= NULL;
// temporary bare pointer<br>
<br>
<br>
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))<br>
{<br>
//...<br>
return 0;<br>
}<br>
pSource.<u><b>set</b></u>(ppSource, false); // setting the
smart pointer.<br>
} <br>
</font></blockquote>
<font face="Verdana">Am I missing something??<br>
<br>
Adi<br>
</font><br>
Adi Shavit wrote:
<blockquote cite="mid4572E9F7.7040801 gentech.co.il" type="cite">
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<p style="margin-bottom: 0cm; margin-top: 0pt;"><font size="-1"><font
face="Verdana">I wasn't even aware of ref_ptr.</font></font></p>
<p style="margin-bottom: 0cm; margin-top: 0pt;"><span
style="font-size: 13px;"><font face="Verdana">I'll try it and let you
know how it goes.<br>
</font></span><span style="font-size: 13px;"></span></p>
<p style="margin-bottom: 0cm; margin-top: 0pt;"><span
style="font-size: 13px;"><font face="Verdana">Adi</font></span><br>
</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;"><span
style="font-size: 13px;"></span><br>
</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;"><span
style="font-size: 13px;"></span></p>
<p style="margin-bottom: 0cm; margin-top: 0pt;"><br>
Matthew wrote:<br>
</p>
<blockquote cite="midekrbio$313n$1 digitaldaemon.com" type="cite">
<pre wrap="">Adi
comstl::interface_ptr<> is obsolete. It offers nothing that
stlsoft::ref_ptr<> does not; it actually offers less.
I don't know why this component has continued to be available. I've just
grepped all my sources and can find only a single use of it (which I've just
changed).
My apologies for having left it in there.
The preferred approach is to use stlsoft::ref_ptr<>. Why? Because it
facilitates forward declaration of a smart pointer specialisation. (I'm
working on a small article to explain how/why, which I hope to publish -
perhaps on CodeProject - soonish.)
I'm changing comstl/smartptr/interface_ptr.hpp as we speak to issue a
warning if included, and will redefine the class to be implemented in terms
of stlsoft::ref_ptr<>.
Sorry about that ... :$
Matthew
And now to the next question ...
</pre>
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Dec 05 2006
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You use conversion constructor and copy assignment, as in:
interface_ptr<IBaseFilter> pSource; // The interface_ptr<> object
{
IBaseFilter* ppSource=3D NULL; // temporary bare pointer
=
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))=
{
//...
return 0;
}
pSource =3D interface_ptr<IBaseFilter>(ppSource, false); // =
setting the smart pointer.
}=20
But since, in your code, you've not used a typedef (I would usually =
define IBaseFilter_ptr) this looks like more of a burden than I'm used =
to.
There's no reason why you should do the typedef thing, of course.
btw, I would normally do this differently, as in:
{
IBaseFilter* ppSource=3D NULL; // temporary bare pointer
=
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))=
{
//...
return 0;
}
else
{
interface_ptr<IBaseFilter> pSource(ppSource, false); // =
setting the smart pointer.
. . .
}
}=20
But again, there's no reason why you _must_ follow the way I do it. So =
it looks like a set() method's called for. (As you'll probably have =
picked up on by now, I don't like adding _any_ functionality until it's =
proven to be needed. But, once it's proven, well ...)
I'll make this change now, and it'll be in beta 31 (31!). That should be =
available in the next 36 hrs, maybe sooner. ;-)
Cheers
Matthew
"Adi Shavit" <adish gentech.co.il> wrote in message =
news:4575C6FD.9060408 gentech.co.il...
I see that ref_ptr doesn't have a set() method.
How can I implement the code I posted before:
// Create a source filter specified by filename
interface_ptr<IBaseFilter> pSource; // The interface_ptr<> =
object
{
IBaseFilter* ppSource=3D NULL; // temporary bare pointer
=
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))=
{
//...
return 0;
}
pSource.set(ppSource, false); // setting the smart pointer.
}=20
Am I missing something??
Adi
Adi Shavit wrote:=20
I wasn't even aware of ref_ptr.
I'll try it and let you know how it goes.
Adi
Matthew wrote:
Adi
comstl::interface_ptr<> is obsolete. It offers nothing that
stlsoft::ref_ptr<> does not; it actually offers less.
I don't know why this component has continued to be available. I've just
grepped all my sources and can find only a single use of it (which I've =
just
changed).
My apologies for having left it in there.
The preferred approach is to use stlsoft::ref_ptr<>. Why? Because it
facilitates forward declaration of a smart pointer specialisation. (I'm
working on a small article to explain how/why, which I hope to publish -
perhaps on CodeProject - soonish.)
I'm changing comstl/smartptr/interface_ptr.hpp as we speak to issue a
warning if included, and will redefine the class to be implemented in =
terms
of stlsoft::ref_ptr<>.
Sorry about that ... :$
Matthew
And now to the next question ...
Dec 05 2006
Adi Shavit <adish gentech.co.il>
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<font face="Verdana">See below...</font><br>
<br>
Matthew wrote:
<blockquote cite="midel4iik$1rnv$1 digitaldaemon.com" type="cite">
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<div><font color="#000000" face="Arial" size="2">You use conversion
constructor and copy assignment, as in:</font></div>
<div> </div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3">
interface_ptr<IBaseFilter>
pSource; // The interface_ptr<> object<br>
{<br>
IBaseFilter* ppSource= NULL;
// temporary bare pointer<br>
<br>
<br>
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))<br>
{<br>
//...<br>
return 0;<br>
}<br>
pSource =
<strong>interface_ptr<IBaseFilter></strong>(ppSource,
false); // setting the smart pointer.<br>
} </font><br>
</font></div>
<div><font color="#000000" face="Arial" size="2">But since, in your
code, you've not used a typedef (I would usually define
<strong>IBaseFilter_ptr</strong>)
this looks like more of a burden than I'm used to.</font></div>
<div> </div>
<div><font color="#000000" face="Arial" size="2">
<div><font color="#000000" face="Arial" size="2">There's no reason
why you should do the typedef thing, of course.</font></div>
</font></div>
</blockquote>
<font face="Verdana">Yes, I guessed that was how you intended it to be
used, though it seems to give the wrong impression, it feels odd.<br>
</font>
<blockquote cite="midel4iik$1rnv$1 digitaldaemon.com" type="cite">
<div><font color="#000000" face="Arial" size="2">
<div> </div>
btw, I would normally do this differently, as in:</font></div>
<div> </div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3"> {<br>
IBaseFilter* ppSource= NULL;
// temporary bare pointer<br>
<br>
<br>
if(FAILED(pGraph->AddSourceFilter(a2w(c_str_ptr(filename)),0,&ppSource)))<br>
{<br>
//...<br>
return 0;<br>
}</font></font></div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3"> else</font></font></div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3"> {</font></font></div>
<div><font face="Courier New">
<strong>interface_ptr<IBaseFilter></strong>
pSource</font><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3">(ppSource, false); // setting the smart
pointer.</font></font></div>
<div> </div>
<div><font color="#000000" face="Courier
New"> .
. .</font></div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3"> }</font></font></div>
<div><font color="#000000" face="Arial" size="2"><font
face="Courier New" size="3"> } </font><br>
</font></div>
<div> </div>
</blockquote>
<font face="Verdana">That's relevant only if pSource is used within the
scope of the else.<br>
If pSource external (e.g. a member), you would still need a
set()[-like] mechanism.<br>
<br>
</font>
<blockquote cite="midel4iik$1rnv$1 digitaldaemon.com" type="cite">
<div><font color="#000000" face="Arial" size="2">But again, there's
no reason why you _must_ follow the way I do it. S</font><font
color="#000000" face="Arial" size="2">o it looks like a <strong>set()</strong>
method's called for. (</font><font color="#000000" face="Arial" size="2">As
you'll probably have picked up on by now, I don't like adding _any_
functionality until it's proven to be needed. But, once it's proven,
well ...)</font></div>
<div> </div>
<div><font color="#000000" face="Arial" size="2">I'll make this
change now, and it'll be in beta 31 (31!). That should be available in
the next 36 hrs, maybe sooner. ;-)</font></div>
</blockquote>
<font face="Verdana">BTW, if the set/ctor would throw for a NULL ptr in
this example, the if check would be unnecessary (assuming it is part of
a bigger try-catch block), and the code would be more readable.<br>
<br>
Adi<br>
<br>
</font>
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Dec 05 2006