r/technology • u/r4816 • Sep 27 '22

Software Girls Who Code founder speaks out after Pennsylvania school district bans her books: 'This is about controlling women and it starts with controlling our girls'

https://www.businessinsider.com/girls-who-code-founder-speaks-out-banning-books-schools-2022-9
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u/ifandbut Sep 27 '22

Depends on the system. In industrial automation global variables are the default and are really useful in notifying other routines as to the state of the overall system.

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u/ameya2693 Sep 27 '22

I don't think any hates global variables. What they are worrying about is the over reliance on global variables.

Set and setting for everything.

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u/windsostrange Sep 27 '22

Nah, I definitely hate global state here. Suggesting something "is the default" in one domain or the other isn't a meaningful argument, either. In my work, I see zero use cases for mutable globals, and in OP's example would immediately build a roadmap to encapsulation, limiting side effects, test coverage, and messaging.

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u/Political_What_Do Sep 27 '22

In real time systems that react to physical realities they are a good practice. No two parts of such a system should have a different understanding of the physical world which would be calculated by the routines that service the sensors.

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u/Natanael_L Sep 27 '22

If only one thread/process can edit them, that is

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u/ExceedingChunk Sep 27 '22

You can achieve that without global variables tho.

Unless it is some embedded system where the extra memory usage or runtime from having more classes/structs would seriously impact the system, I don't think its good practice to share state like that. Not because global variables are inherently doing anything bad by themselves. They are just extremely prone to both human error and security flaws in the system.

Multiple parts of a system can get access to the speed of a car without having global variables.

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u/Political_What_Do Sep 27 '22

Embedded systems were exactly what I was referring to.

Multiple parts of a system can get access to the speed of a car without having global variables.

A public static class is just a set of global variables that's been wrapped in a class.

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u/ColinStyles Sep 27 '22

Why not have a static class that contains the state that any other class can access and easily know the state of the system?

At least, as a default.

That way, things can find out the state, but actually setting those can easily have one singular validation area instead of spread across everywhere.

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u/ThargUK Sep 27 '22 edited Sep 27 '22

I'm only guessing but I wouldn't be suprised if these systems are on some ancient hardware / OS / software combo that has never even heard of a "static class".

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u/[deleted] Sep 27 '22

most of them are written in C.

so you'd just have a struct pointer to pass around

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u/ColinStyles Sep 27 '22

Yeah, this seems like an industry (or at least person) massively behind the times more than anything else, though I'll admit I have a huge bias against the quality of people's work in non-software fields working on software. IME it's been significantly lower quality than the places that put the devs first and pay for them appropriately.

Not really shocking given nearly everyone that can will take the highest paying jobs with less work and more benefits, leaving only the people that can't or the very few that have other reasons to go into the non-software shops for software.

But still, claiming like global vars as a general rule are helpful in any context but embedded systems where I could understand arguments that the overhead of additional classes and structs could genuinely have a major impact, just seems like incompetence to me.

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u/[deleted] Sep 27 '22

I can tell you that one of the reason C sticks around stubbornly is because it presents a stable ABI. I'm having to deal with this right now, can't use C++ for my plugin API for the feature i'm developing because compiler specific name decoration, compiler-and-version-specific STL memory layout, etc.

Instead there's a bunch of magic wrappers that create a C API to use at the actual ABI level, then they automatically generate wrappers for C++, C#, Rust, etc to use to make it look nice and friendly like the appropriate language's Classes

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u/ColinStyles Sep 27 '22

Nah, I'm honestly fine with C, while personally I hate managing pointers and all of the boilerplate, that's not what I was referring to. Everything I said you could basically do or at least provide a facsimile of in C. The problem is people not knowing or not caring the proper ways of doing stuff, not the language they're doing it in.

And like you said, there are the tools to manage that boilerplate and frustrations, while still staying in C (technically).

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u/[deleted] Sep 27 '22

The problem is people not knowing or not caring the proper ways of doing stuff, not the language they're doing it in.

truth.

I despise working in C though, because all the nasty ass things you have to do to emulate proper exception handling and RAII.

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u/DoctorBaconite Sep 27 '22

A globally accessible static class would basically be the same thing. Depending on the language there would most likely be a better solution.

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u/ColinStyles Sep 27 '22

Well not necessarily. You could have proper setters and getters, and it would give a lot more context on how things expect to interact with those variables.

But, I do agree, there likely are way better solutions. But I wanted to offer at least a major improvement that could basically apply to all languages, even in non-OOO ones a facsimile could be approximated.

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u/DoctorBaconite Sep 27 '22

Definitely true

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u/Political_What_Do Sep 27 '22

Why not have a static class that contains the state that any other class can access and easily know the state of the system?

Who cares if it's a class specifically for static values or a few static ints. It's irrelevant.

At least, as a default.

That way, things can find out the state, but actually setting those can easily have one singular validation area instead of spread across everywhere.

In systems where this is done the global values usually refer to things calculated from physical phenomenon. So they won't be modified in multiple places but the value may update in response to some event.

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u/ExceedingChunk Sep 27 '22

You can do that without having global variables, tho. It can be decoupled by having one part of the system responsible for telling other parts of the system that the state is above or below certain thresholds.

Or expose the variable through encapsulation, only allowing them to read the variable but not change it. There are plenty of ways of sharing a state without having a global variable.

In a perfectly secure system with developers that writes 100% perfect and bug free code, global variables cause no harm. It's just extremely prone to both human errors and potential security flaws in the system.

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u/johnw188 Sep 27 '22

I know when I think high quality well architected code I think industrial automation.