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https://github.com/martinmoene/boolean-lite
boolean lite: A strong boolean type for C++98 and later
https://github.com/martinmoene/boolean-lite
boolean cpp11 cpp17 cpp98 header-only no-dependencies single-file
Last synced: 2 months ago
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boolean lite: A strong boolean type for C++98 and later
- Host: GitHub
- URL: https://github.com/martinmoene/boolean-lite
- Owner: martinmoene
- License: bsl-1.0
- Created: 2020-10-31T15:35:18.000Z (about 4 years ago)
- Default Branch: master
- Last Pushed: 2024-01-14T15:24:30.000Z (11 months ago)
- Last Synced: 2024-09-30T00:23:54.602Z (3 months ago)
- Topics: boolean, cpp11, cpp17, cpp98, header-only, no-dependencies, single-file
- Language: C++
- Homepage:
- Size: 46.9 KB
- Stars: 5
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# boolean lite: A strong boolean type for C++98 and later
[](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [](https://opensource.org/licenses/BSL-1.0) [](https://github.com/martinmoene/boolean-lite/actions/workflows/ci.yml) [](https://ci.appveyor.com/project/martinmoene/boolean-lite) [](https://github.com/martinmoene/boolean-lite/releases) [](https://github.com/martinmoene/boolean-lite/blob/master/include/nonstd/boolean.hpp) [](https://conan.io/center/boolean-lite) [](https://wandbox.org/permlink/TMURDai5p2CSWn9a) [](https://godbolt.org/z/E1onYM)
**Contents**
- [Example usage](#example-usage)
- [In a nutshell](#in-a-nutshell)
- [License](#license)
- [Dependencies](#dependencies)
- [Installation and use](#installation-and-use)
- [Synopsis](#synopsis)
- [Notes and references](#notes-and-references)
- [Appendix](#appendix)
## Example usage
```cpp
#include "nonstd/boolean.hpp"
#include
using nonstd::boolean_;
void eat_cookies( int count, boolean_ leave_crumbs )
{
std::cout << "Eat " << count << " cookies and leave " << (leave_crumbs ? "" : "no ") << "crumbs\n";
}
void santa( int num_cookies )
{
const boolean_ leave_crumbs = num_cookies > 4;
// eat_cookies( leave_crumbs, num_cookies ); // Does not compile: wrong argument order
eat_cookies( num_cookies, leave_crumbs ); // Ok
}
int main()
{
santa( 3 );
santa( 5 );
}
```
### Compile and run
```bash
prompt >g++ -std=c++11 -Wall -I../include -o 01-basic.exe 01-basic.cpp && 01-basic.exe
Eat 3 cookies and leave no crumbs
Eat 5 cookies and leave crumbs
```
## In a nutshell
**boolean lite** is a single-file header-only library to provide a strong boolean type.
*boolean lite* is inspired on the article [Fun with Concepts: Do You Even Lift, Bool?](https://vector-of-bool.github.io/2020/10/26/strong-bool.html) by Colby Pike (vector-of-bool), Oct 26, 2020.
**Features and properties of boolean lite** are ease of installation (single header), freedom of dependencies other than the standard library.
## License
*boolean lite* is distributed under the [Boost Software License](https://github.com/martinmoene/boolean-lite/blob/master/LICENSE.txt).
## Dependencies
*boolean lite* has no other dependencies than the [C++ standard library](http://en.cppreference.com/w/cpp/header).
## Installation and use
*boolean lite* is a single-file header-only library. Put `boolean.hpp` in the [include](include) folder directly into the project source tree or somewhere reachable from your project.
## Synopsis
**Contents**
[Documentation of `nonstd::boolean`](#documentation-of-nonstdboolean)
[Configuration](#configuration)
### Documentation of `nonstd::boolean`
The behaviour of boolean differs under C++98 and C++11 and later. Specifically the C++11 version allows the following that is not supported by the C++98 version of `boolean_`.
- copy initialization like `boolean_ b = true;`
- comparison to `bool`, like `boolean_ f( false ); boolean_ result = f == true;`
Note: The name `boolean_` is used for the type to prevent clashing with type `boolean` from the Windows SDK (rpcndr.h(193)).
| Kind | std | Function or method |
|-------------------------|-------|--------------------|
| **Construction** |C++11 | template<typename T *[bool]*> constexpr **boolean\_(T v)** noexcept; |
| |⋮| template<typename T *[!bool]*> explicit constexpr **boolean\_(T v)** noexcept; |
| **Conversion** |⋮| template<typename T *[bool]*> \[[nodiscard]] constexpr **operator T()** const noexcept; |
| |⋮| template<typename T *[!bool]*> \[[nodiscard]] explicit constexpr **operator T()** const noexcept; |
| **Negation** |⋮| \[[nodiscard]] friend explicit constexpr **operator!()** const noexcept; |
| **Equality** |⋮| \[[nodiscard]] friend explicit constexpr **operator==(boolean\_ a, boolean\_ b)** noexcept; |
| |⋮| \[[nodiscard]] friend explicit constexpr **operator!=(boolean\_ a, boolean\_ b)** noexcept; |
| **Ordering** |⋮| \[[nodiscard]] friend explicit constexpr **operator<(boolean\_ a, boolean\_ b)** noexcept; |
| |⋮| \[[nodiscard]] friend explicit constexpr **operator>(boolean\_ a, boolean\_ b)** noexcept; |
| |⋮| \[[nodiscard]] friend explicit constexpr **operator<=(boolean\_ a, boolean\_ b)** noexcept; |
| |C++11 | \[[nodiscard]] friend explicit constexpr **operator>=(boolean\_ a, boolean\_ b)** noexcept; |
| | | |
| **Construction**
|C++98
| explicit **boolean\_(bool v)**;
Note: no copy initialization: `boolean_ b = true;` |
| **Conversion**
|⋮
| operator **bool_type()** const;
Note: bool_type allows for safe conversions |
| **Negation** |⋮| boolean_ **operator!()** const; |
| **Equality** |⋮| friend boolean\_ **operator==(boolean\_ a, boolean\_ b)**; |
| |⋮| friend boolean\_ **operator!=(boolean\_ a, boolean\_ b)**; |
| **Ordering** |⋮| friend boolean\_ **operator<(boolean\_ a, boolean\_ b)**; |
| |⋮| friend boolean\_ **operator>(boolean\_ a, boolean\_ b)**; |
| |⋮| friend boolean\_ **operator<=(boolean\_ a, boolean\_ b)**; |
| |C++98 | friend boolean\_ **operator>=(boolean\_ a, boolean\_ b)**; |
### Configuration
#### Tweak header
If the compiler supports [`__has_include()`](https://en.cppreference.com/w/cpp/preprocessor/include), *boolean lite* supports the [tweak header](https://vector-of-bool.github.io/2020/10/04/lib-configuration.html) mechanism. Provide your *tweak header* as `nonstd/boolean.tweak.hpp` in a folder in the include-search-path. In the tweak header, provide definitions as documented below, like `#define boolean_CPLUSPLUS 201103L`.
#### Standard selection macro
\-Dboolean\_CPLUSPLUS=199711L
Define this macro to override the auto-detection of the supported C++ standard, if your compiler does not set the `__cplusplus` macro correctly.
## Notes and references
- [Fun with Concepts: Do You Even Lift, Bool?](https://vector-of-bool.github.io/2020/10/26/strong-bool.html) by Colby Pike ([vector-of-bool](https://github.com/vector-of-bool)), Oct 26, 2020.
- [A New Approach to Build-Time Library Configuration](https://vector-of-bool.github.io/2020/10/04/lib-configuration.html) by Colby Pike ([vector-of-bool](https://github.com/vector-of-bool)), Oct 4, 2020.
## Appendix
### A.1 Compile-time information
The version of *boolean lite* is available via tag `[.version]`. The following tags are available for information on the compiler and on the C++ standard library used: `[.compiler]`, `[.stdc++]`, `[.stdlanguage]` and `[.stdlibrary]`.
### A.2 Span lite test specification
```Text
boolean: Allows to direct initialize from bool
boolean: Allows to copy initialize from bool (C++11)
boolean: Allows to direct initialize from type convertible to bool
boolean: Allows to compare equal
boolean: Allows to compare unequal
boolean: Allows to compare less than
boolean: Allows to compare less than or equal
boolean: Allows to compare greater than
boolean: Allows to compare greater than or equal
boolean: Allows to compare equal with bool (C++11)
boolean: Allows to compare unequal with bool (C++11)
boolean: Allows to compare less than with bool (C++11)
boolean: Allows to compare less than or equal with bool (C++11)
boolean: Allows to compare greater than with bool (C++11)
boolean: Allows to compare greater than or equal with bool (C++11)
boolean: Supports no discard (C++17, -DBOOLEAN_TEST_NODISCARD=1)
tweak header: Reads tweak header if supported [tweak]
```