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The temptation is always there
(lemmy.world)
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this post was submitted on 08 Oct 2023
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Obligatory, mutable global variables are evil.
The definition of a variable is that it’s mutable. If it’s immutable it’s constant.
I feel like it's like pointers.
"Variable" refers to the label, i.e. a box that can contain anything (like *ptr is a pointer to [something we dont know anything about])
Immutable describes the contents, i.e. the stuff in the box cant change. (like int* ptr describes that the pointer points to an int)
Rust makes it very obvious that there's a difference between constants and immutable variables, mainly because constants must be compile time constants.
What do you call it when a variable cant change after its definition, but isnt guaranteed to be the same on each function call? (E.g. x is an array that's passed in, and we're just checking if element y exists)
It's not a constant, the contents of that label are "changing", but the label's contents cant be modified inside the scope of that function. So it's a variable, but immutable.
As opposed to immutable variables
*confused screaming*
Or mutable constants...
Casts are totally not a danger that should require a comment explaining safety…
And more generally mutable aliasing references of any sort are evil. Doesn't mean they're not useful, just that you need magic protection spells (mutexes, semaphores, fancy lock-free algorithms, atomics, etc) to use them safely. Skip the spell or use she wrong one, and the demon escapes and destroys all you hold dear.