[Idea] boost::optional::map for void f(...)

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp
Domain
backend-api-design

Research direction

Read the existing boost::optional::map overloads and the proposed consume signature first. Confirm the API covers empty optionals and the const, &, and && cases while invoking a void callback only when a value exists; the issue names no files or tests.

Written by the indexing model from the issue text.

Description

As I work boost::optional I have a usecase, where I retrieve optional value and I do not necessary want to transform it, but just to use it if it is there, and if not to ignore it.
Let's assume scenario:

boost::optional<std::string> GetTextOpt();
int stoi(std::string_view);
void SleepMillis(int);

In current implementation, workarounds are necessary, like:

// v1
if(auto res = GetTextOpt().map(stoi)) SleepMillis(res);
// v2
GetTextOpt().map(stoi).map([](int i){SleepMillis(i); return int{};})

Proposal:
Provide new method (e.g. boost::optional::consume) as implementation:

template <typename F>
void consume(F f) [&,const&,&&]
  {
    if (this->has_value())
      f(get());
  }
Dominant language
C++
Stars
60
Forks
75
No merged PRs in 30d

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