46 lines
2.2 KiB
Plaintext
46 lines
2.2 KiB
Plaintext
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- design lessons from the best programming language of all time that everyone loves (not really)
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+ access modifiers as labels (`private:`, `protected:`, and `public:`)
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- although Java and C#'s approach to symbol privacy may be verbose, it has one great advantage: it is stateless.
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- the way they're implemented in C++, it's essentially a bit more parsing state you have to keep track of
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- and you know what other parsing state you have to keep track of in C++? - that's right, the preprocessor.\
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access modifiers, like all tokens, are affected by the preprocessor, and you have to take that into account
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- take the following example:
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```cpp
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class ComfyZone
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{
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std::vector<SoftBed> _soft_beds;
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#if ENABLE_HUGS
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public:
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void hug(Person& person);
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#endif
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int _remaining_hugs = 10;
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};
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```
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- although quite contrived, it illustrates the problem pretty well
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- (before you ask, `_remaining_hugs` needs to be always present because it has to be (de)serialized no matter if hugging functionality is compiled in. otherwise we'd get data loss.)
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- we intended for `_remaining_hugs` to be private, but if hugs are enabled, it becomes public.
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- this can be _very_ hard to spot if you have a big class with lots of declarations inside.
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- this can be worked around by banning access modifiers from appearing in `#ifdef`s, but you have to *realize* that this might happen
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- and I've seen instances of this exact thing occurring in the Unreal Engine codebase, which is *full* of long lists of declarations (made even longer by the prevalence of `UPROPERTY()`s)
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- even if we didn't have the preprocessor, that access modifier is state _you_ have to keep track of
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- I very often find myself needing to scroll upward after <kbd>Ctrl</kbd>-clicking on a field or function declaration, just to find out if I can use it
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- (thankfully IDEs are helpful here and Rider shows you a symbol's visibility in the tooltip on hover, but I don't have Rider on code reviews)
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