Should I still use the keyword explicit for copy constructors?

Question

C++ provides the keyword explicit to suppress implicit conversions via conversion constructors when such conversions should not be allowed. A constructor that's declared explicit cannot be used in an implicit conversion. Use the explicit keyword on single-argument constructors that should not be used by the compiler to perform implicit conversions.

This makes sense, BUT should I still use the keyword explicit for copy constructors? In what other cases would it be useful to use the keyword explicit and why?

Please cite your quote. – Pétur Ingi Egilsson Dec 30 '15 at 16:11 — Pétur Ingi Egilsson, Dec 30 '15 at 16:11

score 4 · Accepted Answer · answered Dec 15 '15 at 10:56

4

It's legal to declare a copy constructor explicit. Declaring it or not really depends on what you want to do. For example, you declare a copy constructor explicit if you want to forbid it from being called implicitly at function calls or with the copy-initialization syntax.

answered Dec 15 '15 at 10:56

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It's legal but generally silly. Such a type isn't CopyConstructible. – T.C. Dec 16 '15 at 01:55

Should I still use the keyword explicit for copy constructors?

1 Answers1