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Re: [std-proposals] finally keyword

From: Abdullah Qasim <iamminecraftredstoner_at_[hidden]>
Date: Sun, 1 May 2022 10:02:30 +0000
Why oppose a good feature??

Finally is already implemented by Microsoft, so implementation difficulty = 0

From: Richard Hodges via Std-Proposals<mailto:std-proposals_at_[hidden]>
Sent: 01 May 2022 14:59
To: std-proposals_at_[hidden]<mailto:std-proposals_at_[hidden]>
Cc: Richard Hodges<mailto:hodges.r_at_[hidden]>
Subject: Re: [std-proposals] finally keyword

On Sun, 1 May 2022 at 10:10, Abdullah Qasim via Std-Proposals <std-proposals_at_[hidden]<mailto:std-proposals_at_[hidden]>> wrote:
If exception is thrown, no destructor is called.

Use a unique_ptr with a custom deleter to act as your "finally" clause. Other languages have it because they don't support RAII.

Here's an example:

template<class Item ,class Deleter>
auto make_finally(Item* item, Deleter del)
    return std::unique_ptr<Item, Deleter>(item, std::move(del));

extern void do_log(FILE* fp, std::string const& contents);

void append_file(std::filesystem::path const& p, std::string const& line)
    auto fin1 = make_finally(::fopen(p.c_str(), "wb+"), &::fclose);
        do_log(fin1.get(), line);
        // handle error here

    // finally happens here


Finally is used for tasks performed regardless of thrown exception, but when exception is caught, control jumps to finally block.


From: Peter C++ via Std-Proposals<mailto:std-proposals_at_[hidden]>
Sent: 01 May 2022 13:04
To: std-proposals_at_[hidden]<mailto:std-proposals_at_[hidden]>
Cc: Peter C++<mailto:peter.cpp_at_[hidden]>
Subject: Re: [std-proposals] finally keyword

that is a feature what destructors and SBRM are fir

available in standard library extensions TS2, as scope guards, but not approved to std for the better.(I am the author)

if there is a simple enough library solution, why should there be a language extension.

watch a recording of one of my "what classes we design and how" to learn when destructors and clean up are actually desirable.
sent from a mobile device so please excuse strange words due to autocorrection.
Peter Sommerlad
+41-79-432 23 32

On 1 May 2022, at 09:52, Abdullah Qasim via Std-Proposals <std-proposals_at_[hidden]<mailto:std-proposals_at_[hidden]>> wrote:

try {


} catch (...) {

  std::cerr << "exception caught!!";


std::clog << "No except caught!";

finally { // already Microsoft extension, but

  cleanup(); // should be in core language


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Received on 2022-05-01 10:02:33