Boost libraries

[steg90]

Hi,

I was wondering how many of you here use the Boost libraries with your Qt applications?

Regards,
Steve

[jacek]

I have added a poll, so that everybody can answer this question easily.

[patrik08]

Hi,
I was wondering how many of you here use the Boost libraries with your Qt applications?
Regards,
Steve


What is Boost libraries?
is this a way to become more source code line? I know only QT libs, curl, tidy, libxslt, libxml2, libexiv2 , Sablot XSLT, all lib wo can build on all OS...

my last discovery libs is http://poppler.freedesktop.org/ to transform pdf to image... but is not possibel to build if automake or autoconf is not the last version..

libraries wo is not possibel to build quick , not give sense to me. this is like to write a cin.getline from string and transform to QString

[steg90]

Hi,

Take a look at http://www.boost.org

Regards,
Steve

[Brandybuck]

I have used Boost, but it's cumbersome to use. It is a very "academic" library that is wholly unsuitable if you are not a C++ expert. It relishes in using all of the advanced features of C++, even for the simplest of problems. It is primarily based not on Object Oriented Programming, but Generic Programming. If you don't know what a functor is, stay away!

Most things that Boost gives you are already available in Qt.

[Michiel]

I have used Boost, but it's cumbersome to use. It is a very "academic" library that is wholly unsuitable if you are not a C++ expert. It relishes in using all of the advanced features of C++, even for the simplest of problems. It is primarily based not on Object Oriented Programming, but Generic Programming. If you don't know what a functor is, stay away!

Most things that Boost gives you are already available in Qt.

Yes, but I've found that you either use Qt all the way, or you don't use Qt. The Qt classes are very interdependent. Whereas boost is meant to be an extension of the standard library.

[Brandybuck]

The Qt classes are very interdependent. Whereas boost is meant to be an extension of the standard library.
Actually, Boost is quite interdependent as well. It's nearly impossible to take just one class (or set of related classes) out of Boost and use it by itself. And while some people are lobbying for parts of Boost to be included in a future C++ standard library, that does NOT mean Boost should be treated as a C++ standard.

[steg90]

I have noticed a lot of the financial trading software houses in the uk use Boost?!

[Brandybuck]

There's a lot of US financial trading companies in New York using Qt :-)

[wysota]

Especially if their software was written by ICS ;)

[steg90]

Pity I'm in the UK! I do know certain financial houses do use Boost here in the UK. I have 'played' with it in the past and used mainly the smart pointers as I often forget to delete pointers and using these, it does it for you :rolleyes:

[wysota]

Smart pointers delete objects? I think we're having a different concept of smart pointers... Mine is that it sets the pointer to 0 once the object pointed is deleted. The concept you described I'd call a hijacking pointer and I don't want my pointers hijacked :) Anyway: QPointer.

[steg90]

Hi,

Not heard of 'hijacking' pointer :p

I'll take a look at QPointer, thanks!

Regards,
Steve

[wysota]

It's hijacking, because when it's destroyed, it destroys the pointed object as well (that's what you said). This means that if it doesn't have ownership of the object, it'll hijack it from the real owner. And it's probably implemented more or less like so:

template <typename T> class HijackingPointer {
public:
HijackingPointer(T *ptr=0), m_ptr(ptr){}
void setPointer(T* ptr){ m_ptr = ptr; }
~HijackingPointer(){ delete m_ptr; }
// + operator T*, operator * and operator ->
private:
T* m_ptr;
};

I don't think I have to link to a bloated library just for this small snippet.

[jacek]

I don't think I have to link to a bloated library just for this small snippet.
std::auto_ptr from STL is the one that "hijacks" pointers, not the classes from Boost's Smart Pointers family.

[wysota]

So Boost pointers won't do that for you:

. I have 'played' with it in the past and used mainly the smart pointers as I often forget to delete pointers and using these, it does it for you.

Right?

[jacek]

So Boost pointers won't do that for you: [...] Right?
It depends which one you choose.

[wysota]

So is there a pointer in the family that deletes objects pointed to when it's deleted but doesn't hijack the object (for me this is contradictory, but maybe I just can't imagine the situation)?

[jacek]

So is there a pointer in the family that deletes objects pointed to when it's deleted but doesn't hijack the object (for me this is contradictory, but maybe I just can't imagine the situation)?
Boost has three kinds of smart pointers: shared pointers, which share the ownership amongs them,
scoped pointers, which take the ownership for themselves,
weak pointers, which don't take the ownership, but know when the object was destroyed.
All these three kinds of smart pointers are well behaved and the term "hijacking" isn't appropriate. It's just as if you said that QCoreApplication::postEvent() "hijacks" pointers, because it takes their ownership --- it doesn't, it's just a part of its contract.

If you want to call something "pointer hijacking", take a look what std::auto_ptrs do on copy --- they're like hungry hienas, which steal a dead antilope from each other.

[wysota]

So "weak pointer" is an equivalent of QPointer, "scoped pointer" does to pointers more or less what QMutexLocker does to mutexes and shared pointer is a combination of the two that does reference counting. Correct? Of course all these might fail if you use any regular pointers with the same object.

[jacek]

Correct?
Yes.


Of course all these might fail if you use any regular pointers with the same object.
Like everything which deals with pointers.

[wysota]

Like everything which deals with pointers.

But not QPointer :)

[Michiel]

But not QPointer :)

It's nothing to boast about if your smart pointer is restricted to QObject descendants. :p

[kiker99]

What I've tried from boost yet was just great. If you need to do parsing: Have a look at Boost.Spirit. It uses TMP (template meta programming) and gives C++ a completely new dimension :)

[magland]

For those who have successfully used boost libraries with Qt, I would be interested to learn about your experience... is it straightforward to integrate, and are there any packages or example projects using Qt with boost?

[jacek]

is it straightforward to integrate, and are there any packages or example projects using Qt with boost?
I haven't tried all of the boost classes, but so far I had no problems at all.

See this page: http://boost.org/doc/html/signals/s04.html#id1633734

[spud]

Most often it is very easy to use boost with Qt, since most of the libraries are header only libraries. You only have to download it and modify your include path. The only libraries which have to be compiled and linked to are(from http://www.boost.org/more/getting_started/windows.html#header-only-libraries):


Boost.Filesystem
Boost.IOStreams
Boost.ProgramOptions
Boost.Python (see the Boost.Python build documentation before building and installing it)
Boost.Regex
Boost.Serialization
Boost.Signals
Boost.Thread
Boost.Wave

and obviously most of these offer functionalities which normally you'd let Qt take care of. I've only used them for projects where I couldn't use Qt.