Does not Developers get confused if there are too many global variables?

Lost User

Yeah, I usually create a small static class to hold all the static vars.

Lost User

Yeah, I usually put them all in a small, dedicated static class. Seems to work well for me.

R Erasmus

Agree, they should read up on data coupling a bit.

"Program testing can be used to show the presence of bugs, but never to show their absence." << please vote!! >>

Stefan_Lang

OriginalGriff wrote:

I'm just glad var is shorter and easier to type than dynamic

If differences in typing speed is your most pressing problem, get an editor where it isn't (hint: language sensitive autocompletion helps).

Stefan_Lang

I've found that some people prefer defining globals, or defining variables within too wide a scope just for the sake of not having to pass them as a parameter to a function, because that would require typing additional parameters. Sadly, even language-sensitive editors cannot help a lot with this. Still, additional typing should never affect your coding design decisions! For example I've seen classes with lots of private member variables that are really only required to hold temporary flags and states of operations, rather than indicate the actual state of the object. I consider that almost as bad as using globals. I know I like declaring globals or class members instead of local vars when prototyping new code when I'm not yet sure about the final design. But, even if I often don't clean up my code to the degree I should, at the very least I'll move my variables to the proper scope. It's the minimum I can do to keep my interfaces clean.

Rob Grainger

Actually, public statics are nearly as bad. The crucial factor here is that they can introduce problems in the presence of concurrency - if two tasks/threads/... attempt to update the same global/static, the state of the system becomes indeterminate. Singletons are frequently referred to as an anti-pattern for exactly this reason. All such rules are made to be broken, however, and I sometimes have to use public statics - to avoid passing some variable references absolutely everywhere (because most languages don't have good support for lexical scoping). But I do think about each and every such useful very carefully and prefer to find alternatives.

"If you don't fail at least 90 percent of the time, you're not aiming high enough." Alan Kay.

Rob Grainger

That's one big problem, I've seen many projects like this (especially in VB6). The list of globals has a tendency to grow, never to shrink. Cleaning (or even understanding) such programs is an exercise in frustration.

"If you don't fail at least 90 percent of the time, you're not aiming high enough." Alan Kay.

StatementTerminator

It's simple really: variables should be visible only where they need to be, which means the scope should be as limited as possible. There are lots of reasons for this, including the fact that some of the worst bugs in the world are caused by using variables with too wide of a scope. I once saw a daily import of very important financial data blow up due to such a bug. The guy who wrote the import routine in T-SQL read the identity of the last inserted record of a certain table using @@IDENTITY. This was important because if it got the wrong identity back foreign keys would get all screwed up during the import. Anyway, guess what happened when another developer innocently added a trigger to the table for bulk imports? Yeah. @@IDENTITY is essentially global in scope, so adding an insert trigger to the table--which should have been fine--blew it the hell up. That ended up costing a good chunk of real money for the company. It was also a hard one to debug, because the trigger was the only new code and everyone looked over it and it looked fine, it took a while to figure out what was happening with the import routine which had been in production for years. And all because @@IDENTITY was used instead of SCOPE_IDENTITY. There are very few cases where global variables are a good idea. They make good time bombs though.

GenJerDan

Rob Grainger wrote:

Actually, public statics are nearly as bad. The crucial factor here is that they can introduce problems in the presence of concurrency - if two tasks/threads/... attempt to update the same global/static, the state of the system becomes indeterminate.

Yeah, I hate it when a program ignores what I've written and starts doing things on its own.

YouTube and My Mu[sic], Films and Windows Programs, etc.

patbob

I see people use global variables (and class statics, and sometimes singletons) when they don't want to think too hard about how, and where, it will need to be accessed. Confusion? Yeah. Discomfort? Those who use them a lot, get used to keeping track of their scope of use manually.. and once you get into that style of coding, more aren't necessarily much worse. Conveying that scope of use information to the next programmer is difficult, and very quickly the code ends up on a toboggan ride to a very warm place. Unless they're used to hold immutable data that's set up very early in the program, they're usually a maintenance nightmare.

We can program with only 1's, but if all you've got are zeros, you've got nothing.

RafagaX

If your program uses global variables, they tend to grow over time, given that every new person that comes next will introduce their own (often redundant) global variables, not for laziness, but because they don't know whether using and existing one will have any side effects anywhere else in the code base, so please don't use them or at least keep it at minimum.

CEO at: - Rafaga Systems - Para Facturas - Modern Components for the moment...

StatementTerminator

RafagaX wrote:

because they don't know whether using and existing one will have any side effects anywhere else in the code base

Exactly! Because in order to work with global variables and avoid unwanted side-effects, you have to understand how the variables are used in the entire scope, and since they're global that means the whole enchilada! Imagine what you'd have to do to in order to safely re-factor the code to clean up the existing global variables. So the global variables become a house of cards that no one dares to touch. Adding "special" new ones that look just like old ones but were added by a different dev who didn't know exactly how the old ones were being used...that becomes the safe way to go :wtf:

dave wg halsall

I have a project that uses quite a few public statics to hold configuration information. IE. different customers have different features and expect slightly different behaviour from the application. I think this is fairly reasonable as they are set only at the time the application starts up and never change. I'd be interested to know how other people would tackle this.

BrainiacV

In the olden days all there were, were global variables. You young'uns need to learn how to suck it up and program like a real men. :laugh:

Psychosis at 10 Film at 11 Those who do not remember the past, are doomed to repeat it. Those who do not remember the past, cannot build upon it.

BotReject

Depends what you mean by 'too many'. Not everything has to be object-oriented, there is nothing wrong in using non-OO code for a simple script of a few hundred lines, or indeed using semi-OO as might be used in classic C++ for a a few thousand lines. It is not wise to insist on dogma if it means using a bazooka to swat a fly. Indeed, scripts were intended to be kept simple, it is only fairly recent demands to increase the complexity of JS that has resulted in attempts to make it OO. Personally, I think that if code gets this complex then it's better to use server-side C# or something similar, though people are doing some heavy work with JS these days and doing it well. That's my opinion as a humble amateur. One thing I have learnt over the years - for every coding dogma there is at least one exception, almost without exception.