Is STL final?

[farid....@gmail.com]

Are std template classes inheritable in user code ?

Or should they be marked final?

regards,

FM.

[Ville Voutilainen]

On Sun, 7 Apr 2019 at 16:11, <farid....@gmail.com> wrote:
>
> Are std template classes inheritable in user code ?

Yes.

> Or should they be marked final?

No, absolutely not, that would prevent useful wrapping techniques.

[Farid Mehrabi]

Good. I was thinking after introduction of the keyword 'final' such code may become obsolete. Is there any specific explicit wording in the std docs about this?

در یکشنبه 7 آوریل 2019، ساعت 17:42:32 (UTC+4:30)، Ville Voutilainen نوشته:

[Daniel Krügler]

Am So., 7. Apr. 2019 um 15:32 Uhr schrieb Farid Mehrabi
<farid....@gmail.com>:

>
> Good. I was thinking after introduction of the keyword 'final' such code may become obsolete. Is there any specific explicit wording in the std docs about this?
>

There is no specific wording, but we had in the past an issue about
that situation, which was resolved as NAD:

https://cplusplus.github.io/LWG/issue2113

There is no wording in the standard, that allows an implementation to
mark STL components as final, therefore any implementation that would
do that would be non-conforming.

- Daniel

[Robert Haberlach]

No, it's by definition. See the header prototypes. 

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[Nicol Bolas]

On Sunday, April 7, 2019 at 9:43:15 AM UTC-4, Columbo wrote:

No, it's by definition. See the header prototypes. 

More specifically, [derivation]/4 says:

> All types specified in the C++ standard library shall be non-final types unless otherwise specified.

[Peter Sommerlad]

In my book, using final is always a mistake. If i were around when final and override were introduced, i would have been strongly against.

„Override“ is either checked anyway by compilers or displayed by IDEs.

In C++ i can not perceive any useful application of final, that would not require perfect foresight, which is typically not possible.

My cHF0.02

Peter

sent from a mobile device so please excuse strange words due to autocorrection.
Prof. Peter Sommerlad
peter.S...@hsr.ch
+41-79-432 23 32

[Hyman Rosen]

On Sun, Apr 7, 2019 at 1:21 PM Peter Sommerlad <peter.s...@hsr.ch> wrote:

In my book, using final is always a mistake. If i were around when final and override were introduced, i would have been strongly against.

You're right about final but you're wrong about override.  Final is for the
optimizationists who want the compiler to avoid dispatching when it can.
 Override is for the programmers to be informed when someone upstream
changes the profile of a virtual function.  This has happened repeatedly,
for example, in clang's preprocessor interface, and without override, you
just notice that your code has stopped working without knowing why.