Why people dislike global variables so much while I find them so convenient?

rempas rempas at tutanota.com
Wed Jan 26 08:46:04 UTC 2022

On Tuesday, 25 January 2022 at 14:28:24 UTC, H. S. Teoh wrote:
> [ The problem with global variables ... it makes debugging an 
> extremely unpleasant experience. ]

Yeah, it makes sense. You need to be sure that your functions 
will be called in a specific order hence why this can be 
dangerous in libraries.

> [ Another problem with global variables is that ... just pass 
> the 2nd connection and you're done. ]

Yeah, you are right and this is why I asked for examples because 
I haven't worked with everything and I just don't know. I will 
also have a problem with my project when I add multi-thread 
support so I will change it's structure now that it is smaller.

> Whenever you have multiple shared parameters between a bunch of 
> functions, that's a sign that they probably should be member 
> functions of a common struct or class.  The shared parameters 
> should be in the struct, then you don't have to explicitly pass 
> them around, you just add another function to the struct and 
> they gets passed implicitly for you.

This actually makes total sense. I will change my program to do 
that instead! Thanks!

> Either group your parameters in a single struct, or make your 
> functions members of the struct. Then all you have to do is add 
> another field to your struct and you're done. No tedium.

Actually, I was wondering something. Maybe I should read the 
whole reference first but I'll just ask in case you know. Is 
there a way to just declare a struct/class method and define it 
outside the struct/class like in C++? It will be very annoying to 
have all my functions be in the same file. The first method seems 
better to me.

> Using a struct/class also takes care of the instancing problem: 
> if one day you suddenly need a different set of parameters, you 
> just create a different instance of your struct and everything 
> Just Works(tm). If they were global variables, then there can 
> only be one instance of every variable, and you're stuck up the 
> creek without a paddle.
> T

Yeah, I didn't thought about that before. That's why I'm glad 
people always try to help! Thanks a lot for your time!

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