Portin from Python to C++

[SuperCamel]

Right now the biggest thing that sends me for a loop are pointers. I understand what they are, I just don't always understand why they get used when they do. I read C++ code (for example, the code snippets on this page: http://doc.qt.digia.com/qt/webkit-fancybrowser.html) and it's completely non-obvious to me why sometimes variables are declared as pointers and sometimes not.

Yeah I dunno if I understand all the reasons for using pointers. One reason is because it's quicker and more efficient to create copies of a pointer than to create copies of an entire class.

Rule of thumb though, don't use pointers unless you need to.

[zombifier25]

I'm still a learner so I'm also interested in what pointers are primarily used for.

But I do know one use of pointers in C++ is taking advantage of inheritance and polymorphism. Those 2 features are useful in some cases (I took advantage of them in my Uno playing program by declaring the classes Human and AI as inheriting from Players, and have the Players morph into Human or AI)
Also, Qt programs and books usually encourage you to use pointers and "new" them instead of declaring the objects directly. Still dunno why

[lykwydchykyn]

I wanted to get back to this conversation with an example of what confuses me about pointer use.

See the code examples on this page:

http://zetcode.com/gui/qt4/layoutmanagement/

Notice that in verticalbox.cpp all the widgets are created as pointers using "new".

But in main.cpp, "window" is just created directly.

Why is it different?

[GeneralZod]

I wanted to get back to this conversation with an example of what confuses me about pointer use.

See the code examples on this page:

http://zetcode.com/gui/qt4/layoutmanagement/

Notice that in verticalbox.cpp all the widgets are created as pointers using "new".

But in main.cpp, "window" is just created directly.

Why is it different?

window isn't given a parent, so Qt doesn't delete it for you - therefore, it's safe to handle destruction yourself. May as well just allocate it on the stack

[lykwydchykyn]

window isn't given a parent, so Qt doesn't delete it for you - therefore, it's safe to handle destruction yourself. May as well just allocate it on the stack

Would it be safe to generalize that I should only create qobjects/qwidgets on the stack if:

- They only need to exist temporarily during a function call (e.g. dialog box)
- I'm in main(), and thus the program will be done when the function returns.

Fair enough?

[GeneralZod]

Would it be safe to generalize that I should only create qobjects/qwidgets on the stack if:

- They only need to exist temporarily during a function call (e.g. dialog box)
- I'm in main(), and thus the program will be done when the function returns.

Fair enough?

Add "and they aren't given a parent", and that sounds like a good rule - I can't think of any exceptions offhand.