Seeking help with opend std (page 2)

On 1/12/25 11:25 AM, Anton Pastukhov wrote: > On Saturday, 11 January 2025 at 05:12:02 UTC, monkyyy wrote: >> On Friday, 27 December 2024 at 21:15:40 UTC, monkyyy wrote: >>> >> >> Still want help >> >> https://github.com/opendlang/d/blob/main/source/odc/algorthims.d >> >> will take criticism from the usual suspects > > Please make popFront and popBack actually return popped values thanks Historically that did not work at a time when - C++ was the ruler - Strong exception guarantee mattered - Move constructors were not available T popFront() { /* ... */ // 1) Mutate the range return front; // 2) Copy the element } The problem is with copying that popped value. If the copying itself throws, the range is already modified. Such topics have been covered extensively in books like Exceptional C++ by Herb Sutter. If strong exception guarantee is indeed needed, the correct API is to provide front() and popFront() separately. But once you have front() anyway, why conflate the two actions of popping and providing in popFront() again? So the current D InputRange API works. Ali

6 days ago

Re: Seeking help with opend std

Posted by Anton Pastukhov
in reply to Ali Çehreli

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Anton Pastukhov

Posted in reply to Ali Çehreli

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On Monday, 13 January 2025 at 21:29:38 UTC, Ali Çehreli wrote:

On 1/12/25 11:25 AM, Anton Pastukhov wrote:

On Saturday, 11 January 2025 at 05:12:02 UTC, monkyyy wrote:

On Friday, 27 December 2024 at 21:15:40 UTC, monkyyy wrote:

Still want help

https://github.com/opendlang/d/blob/main/source/odc/algorthims.d

> >

will take criticism from the usual suspects

Please make popFront and popBack actually return popped
values thanks

Historically that did not work at a time when

C++ was the ruler
Strong exception guarantee mattered
Move constructors were not available

T popFront() {
/* ... */ // 1) Mutate the range
return front; // 2) Copy the element
}

The problem is with copying that popped value. If the copying itself throws, the range is already modified. Such topics have been covered extensively in books like Exceptional C++ by Herb Sutter.

If strong exception guarantee is indeed needed, the correct API is to provide front() and popFront() separately. But once you have front() anyway, why conflate the two actions of popping and providing in popFront() again? So the current D InputRange API works.

Ali

This is just a matter of ergonomics.

auto x = myArr.popFront();

is slightly more convenient than

myArr.popFront()
auto x = myArr.front;

Re: exceptions, for builtin range data types it's realistic to give nothrow guarantee. For user-defined types, it's responsibility of the user to take care of it

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