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Merged
neatudarius merged 1 commit into from
Apr 4, 2025
Merged

Add proper example for optional ref in root README #116

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31 changes: 11 additions & 20 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,6 @@ The next code snippet shows optional range support added in [Give *std::optional
#include <beman/optional/optional.hpp>
...

// Example from P3168R2: basic range loop over C++26 optional.

beman::optional::optional<int> empty_opt{};
for ([[maybe_unused]] const auto& i : empty_opt) {
// Should not see this in console.
Expand All @@ -69,28 +67,21 @@ The next code snippet shows optional reference support added in [`std::optional<
#include <beman/optional/optional.hpp>
...

{
// Empty optional example.
std::optional<int> std_empty_opt;
beman::optional::optional<int> beman_empty_opt;
assert(!std_empty_opt.has_value() &&
!beman_empty_opt.has_value()); // or assert(!std_empty_opt && !beman_empty_opt);
std::cout << "std_vs_beman: .has_value() matches?: "
<< (std_empty_opt.has_value() == beman_empty_opt.has_value() ? "yes" : "no") << "\n";
}
struct Cat { ... };

beman::optional::optional<Cat&> find_cat(std::string) { return {}; }
beman::optional::optional<Cat&> do_it(Cat& cat) { return { cat }; }

{
// Optional with value example.
std::optional<int> std_opt = 26;
beman::optional::optional<int> beman_opt = 26;
assert(std_opt.has_value() && beman_opt.has_value()); // or assert(std_opt && beman_opt);
assert(std_opt.value() == beman_opt.value()); // or assert(*std_opt == *beman_opt);
std::cout << "std_vs_beman: .value() matches?: " << (std_opt.value() == beman_opt.value() ? "yes" : "no")
<< "\n";
beman::optional::optional<Cat&> api() {
beman::optional::optional<Cat&> cat = find_cat("Fido");
return cat.and_then(do_it);
}

beman::optional::optional<Cat&> cat = api();

```

Full code can be found in [./examples/optional_ref.cpp](./examples/optional_ref.cpp). Build and run instructions in [./examples/README.md](./examples/README.md).
Full code can be found in [./examples/optional_ref.cpp](./examples/optional_ref.cpp). Build and run instructions in [./examples/README.md](./examples/README.md). Or try it on Compiler Explorer: [optional_ref.cpp@Compiler Explorer](https://godbolt.org/z/MxjdvTTov).

## How to Build

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