Thread: Global Varibles

Originally Posted by motocross1

Sorry if I was a bit overly cocky - it does feel somewhat like a competition.
But, I think using a namespace in my situation is a perfectly legitamate C++ usage.
I actually love it.

(I really do get all of your arguments too. They're fine in general, but just not for my situation.)

Many newcomers on this board is in the same situation as you. They are writing code purely for themselves as a hobby-activity, and thus they feel many of the guidelines that are provided here are not applicable to them. And to a certain extent, they are right. If you are writing a tiny tiny program (less than 100 lines) to check whether or not a string is palindrome or not (very common problem for beginners), it is very tempting to throw a goto or 2 in there, because gotos are easier than loops and they work just as well in that particular case.
This is all fine and dandy, but the thing about gotos is that they don't scale very well, when your programs reach 1000 lines of code, excessive use of gotos will make the code SIGNIFICANTLY harder to follow, and when the code is 100000 lines and there are 12 other programmers involved, using gotos where there should really be a loop, the code will be flat out impossible to troubleshoot or even read and understand.
As such, all of the experienced programmers on this board always argue strongly against using gotos even in tiny programs, because it is important as a programmer to get into the right mindset from the beginning, and not resort to hacky half-arsed solutions. If you cultivate a strong coding discipline and shun some of these horrid coding loopholes, you will grow to be a better programmer in the long run.

Now i know you're not a complete beginner per se, and you might argue that gotos are worse than global variables (rightly so i would say). But the point still stands, in regards to coding, steer clear of the easy solutions, do things properly from the start, and 5 years from now you would never even consider using globals or any other form of cheap loophole to get a piece of code to do what you want, you will just do it properly, on pure instinct and habit.

I think this is worth mentioning aswell, stop thinking about how you can get this darned thing to just work and be done with it, and start thinking about how you as a coder can grow (even if just a tiny bit), by solving this properly.

FYI:

The one thing that is harder to do when global variables are used that surprised me was writing test code is harder to do cleanly.

Tim S.

Originally Posted by motocross1

GOTO is a stupid example - it IS hard to follow.

if( !User.isLoggedIn ) DoLogin();
...is the same as...
if( !global_isLoggedIn ) DoLogin();
Both are easy to track and understand.

My code is very efficient, stable, readable, manageable, scalable, and "Professional".
Just quit already.

So in 100.000 lines of code, where would you go to find out what is wrong when global_isLoggedIn suddenly changes for no apparent reason?

In the case of User.isLoggedIn(), all you have to do is to check that specific class (User), since nobody else will have access to the bool that decides whether the user is logged in or not.

Why would i change global_isLoggedIn you might ask? Well say you don't, maybe one of your coworkers changes it in some obscure function where it shouldn't be touched at all, maybe he did i by accident, or he did it on purpose because he felt confident no other classes or functions depend on it.

The private keyword is there to tell other coders to leave your stuff alone.

Good luck debugging that, ill just open User.cpp and find out which function is the culprit, i might have to go through 5-10 functions, you will have between 1 and a googol lines of code to wade through, since you didn't specify who can mess with your variables, and who can't.

Stop kidding yourself, using global variables instead of proper encapsulation in software development is like using blue cheese instead of reinforced concrete in structural engineering. Sure, it works when the project is tiny and can fit on your desk, but when you scale it up to a usable size, it collapses on itself and suddenly there is cheese everywhere.

Originally Posted by motocross1

"where would you go to find out what is wrong"
1-billion lines of code, find this: global_isLoggedIn=(true|false);
Very easy.
Duh.

Assuming that the code is in one file (Which it won't be), also assuming that there won't be 1500 different places where your global is being changed, and only one of them is wrong.

Encapsulation is a cornerstone of the OOP concept, which in turn is a cornerstone of alot of software being written today. OOP has been with us for a while now, it took many great minds and thousands of man-years to come up with and refine. Thousands of PHDs and Professors swear by it and teach it on a daily basis, millions of programmers know OOP in and out and work with it many hours a day, billions of dollars are being poured into big software projects that utilize OOP, millions of pages in thousands of books have been written on the subject.

But hey, i guess they're all wrong, you must be right. Damn, why didn't you tell us this sooner?

Code:

                          (
                       (   )  )
                        )  ( )
                        .....
                     .:::::::::.
                     ~\_______/~

HUMBLE PIE FROM ME TO YOU! BE SURE TO EAT IT ALL!

I've changed my mind: Long live the "Global Varibles" thread!

Originally Posted by motocross1

My code is very efficient, stable, readable, manageable, scalable, and "Professional".

I believe the "Professional" part, quotes included.