https://github.com/kudashevs/calculator-via-injection
A simple calculator app that implements math operations via a dependency injection.
https://github.com/kudashevs/calculator-via-injection
case-study dependency-injection php
Last synced: 3 months ago
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A simple calculator app that implements math operations via a dependency injection.
- Host: GitHub
- URL: https://github.com/kudashevs/calculator-via-injection
- Owner: kudashevs
- License: mit
- Created: 2018-09-16T17:45:21.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2023-09-29T15:57:51.000Z (over 1 year ago)
- Last Synced: 2025-01-21T16:38:44.137Z (4 months ago)
- Topics: case-study, dependency-injection, php
- Language: PHP
- Homepage:
- Size: 49.8 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# Calculator Via Injection
This is a case study that aims to show one of the possible ways of injecting functionality in PHP language.
## How it works
We are given a [Calculator](src/Calculator.php) class that requires an instance of `Calculable` as its constructor parameter.
The `Calculable` is just an abstraction of some calculations, which are represented by a `calculate` method, that
accepts a variable number of arguments ([variadic function](https://en.wikipedia.org/wiki/Variadic_function)). To
start using the injection, we need to define a piece of functionality (a math operation in our case) that conforms
to our abstraction, and provide its instance to the `Calculator` at the moment of its instantiation. The instance
of `Calculator` is going to retain the injected functionality and use it each time the calculation is requested.
```php
$addition = new Calculator(new Addition());
echo $addition->calculate(1, 2); // results in 3
```
for more usage examples, please see the [examples](examples/) folder.
## Notes
By default, the package provides four classes that correspond to the basic math operations (addition, subtraction,
multiplication, division). Each class uses the `Validator` trait to perform validation. The `Division` class overrides
the default trait's method and extends its functionality. For more information see the [Operations](src/Operations/) folder).
The validation of input arguments is implemented in the [Validator](src/Operations/Validator.php) trait. Therefore, every operation
might use the trait for validation, or might not. We don't force the `Calculable` implementations to use the predefined validation.
**Note** The decomposition might look strange, and it really is. However, this is just a study case on how we can use the dependency
injection to assign some predefined behavior to a variable. It almost imitates a [closure study case](https://github.com/kudashevs/calculator-via-closures).
## Things to learn
[//]: # (@todo don't forget to update the line numbers)
Things that you can learn from this case study:
- [how the constructor dependency injection works](src/Calculator.php#L19)
- how to [delegate calls/messages to another object](src/Calculator.php#L34)
- how to [override and extend methods inherited from traits](src/Operations/Division.php#L30)
## License
The MIT License (MIT). Please see the [License file](LICENSE.md) for more information.