Rundown of how each Effective C++ item relates to Swift

In this post we talked about how some of the items in Effective C++ might apply to Swift.

Many of the entries highlighted some limitations on the part of Swift, so some might think this post was a criticism of Swift.  Actually far from it – many of the items in Effective C++ are pointing out dangers of C++ where you can shoot yourself in the foot if you aren’t careful.  In most cases, when you look at the equivalent issue in Swift, it’s a non-issue.

For completeness, here is a rundown of every item, what kind of article it is, and how it applies to Swift:

Item Danger or benefit? In Swift
1: View C++ as a federation of languages Probably a benefit? Applies the same
2: Prefer consts, enums and inlines to defines Pre-processor dangerous! No preprocessor!  No reflection or lisp-style macros either tho.
3: Use const whenever possible Benefit let and mutating are there, but they only go so far. 
4: Make sure that objects are initialized before they’re used Danger Fully locked down, you have to initialize variables properly.
5: Know what functions C++ silently writes and calls Bit of both Swift writes some init methods automatically, though it’s nowhere near as potentially confusing as C++
6: Explicitly disallow the use of compiler-generated functions you do not want Benefit Doesn’t really apply to Swift
7: Declare destrutors virtual in polymorphic base classes Danger Not an issue, every method is virtual in Swift classes.
8: Prevent exceptions from leaving destructors Danger No exceptions in Swift!
9: Never call virtual functions during construction or destruction Danger Swift’s enforcement of initializing the super and all member variables helps prevent this problem
10: Have assignment operators return a reference to *this More of a convention No assignment (or copy constructors) in Swift
11: Handle assignment to self in operator= Danger No assignment (or copy constructors) in Swift
12: Copy all parts of an object Danger Still dangerous, but without as good tools to fix it (no copy constructors on structs!)
13: Use objects to manage resources Benefit ARC + deinit = same benefit!  So long as you’re careful about variable capture.
14: Think carefully about copying behavior in resource-managing classes Good advice Good advice applies, take it
15: Provide access to raw resources in resource-managing classes Good advice Good advice applies, take it
16: Use the same form in corresponding uses of new and delete Bit of both No need for explicit memory management in Swift.  That’s good, right?
17: Store newer objects in smart pointers in standalone statements Bit of both ARC means every pointer in Swift is a smart pointer, so all good.
18: Make interfaces easy to use correctly and hard to use incorrectly Good advice Good advice applies, take it
19: Treat class design as type design Good advice Good advice applies, take it
20: Prefer pass-by-reference-to-const to pass-by-value Bit of both Doesn’t really apply to Swift, though I wish it had proper const support.
21: Don’t try to return a reference when you must return an object. Danger ARC means every pointer in Swift is a smart pointer, so all good.
22: Declare data members private Benefit No public/private in Swift – yet.  It’s coming apparently.
23: Prefer non-member non-friend functions to member functions Bit of both Seems to apply the same to Swift.
24: Declare non-member functions when type conversions should apply to all parameters Bit of both Type conversion in Swift is very different, and rarely implicit, so this doesn’t really apply.
25: Consider support for a non-throwing swap Bit of both No exceptions in Swift, so your swap will definitely be non-throwing.
26: Postpone variable definitions as long as possible Good advice Good advice applies, take it
27: Minimize casting Danger Swift type casting is a lot safer/saner/more powerful than C++. 
28: Avoid returning “handles” to object internals. Good advice Good advice applies, take it
29: Strive for exception-safe code Danger Swift code is definitely exception-safe.
30: Understand the ins and outs of inlining Danger If compilers aren’t better at humans at inlining these days, something has gone wrong.
31: Minimize compilation dependencies between files Danger No more headers!
32: Make sure public inheritance models “is-a” Good advice Good advice applies, take it
33: Avoid hiding inherited names Danger Swift mandates you override a method if it has the same signature as a parent class version
34: Differentiate between inheritance of interface and inheritance of implementation Good advice Good advice (mostly) applies, take it
35: Consider alternatives to virtual functions Good advice I need to research this one…  It probably applies.
36: Never redefine an inherited non-virtual function Danger No non-virtual functions in Swift
37: Never redefine a function’s inherited default parameter value Danger Swift behaves the same right now but this has been declared a bug in the compiler
38: Model “has-a” or “is-implemented-in-terms-of” through composition. Good advice Good advice applies, take it
39: Use private inheritance judiciously Danger Private inheritance is a weird C++ thing, don’t sweat it.
40: Use multiple inheritance judiciously. Danger No multiple implementation inheritance in Swift.  Most people think this is the right idea.
41: Understand implicit interfaces and compile-time polymorphism Benefit Swift has compile-time polymorphism through generics much like C++ templates but they differ a lot (C++ templates are crazy powerful crazy complicated)
42: Understand the two meanings of typename Confusing, if not dangerous You know how I said C++ templates got crazy complicated?  This is part of that.
Item 43: Know how to access names in templatized base classes Confusing, if not dangerous I need to research this one… probably doesn’t apply.
Item 44: Factor parameter-independent code out of templates Danger Is it possible Swift generics use could result in code bloat?  Would really need some serious LLVM digging to find out.
Item 45: Use member function templates to accept “all compatible types.” Benefit Swift generics provide much of the same features.  Needs a bit more research.
Item 46: Define non-member functions inside templates when type conversions are desired Benefit Swift is not very implicit type-conversion friendly (opinion probably divided on whether this is a good or bad… I think bad, most probably think good)
Item 47: Use traits classes for information about types Benefit I need to research this one… Associated types and type constrains in Swift seem related to this.
Item 48: Be aware of template metaprogramming A bizarre C++ rabbit hole Probably best not to think about it.
Items 49-52: New and delete Various Swift does have UnsafePointer and malloc so maybe these are kind of topics are not as much of a non-issue as you might think at first.
53: Pay attention to compiler warnings Good advice Good advice applies, take it
Item 54: Familiarize yourself with the standard library, including TR1 Benefit Objective-C, like C++, has a huge library behind it, all of which can be used from Swift.  Question is, how much will be ported to a more Swift-like form?  Time will tell
Item 55: Familiarize yourself with Boost Beneft Boost is fantastic.  But early indications are, there’s a huge community of Swift developers looking to do similar things.



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