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https://github.com/RyotaMurohoshi/ValueObjectGenerator

ValueObjectGenerator is Generator for ValueObjects.
https://github.com/RyotaMurohoshi/ValueObjectGenerator

csharp csharp-library csharp-sourcegenerator

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ValueObjectGenerator is Generator for ValueObjects.

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# ValueObjectGenerator

`ValueObjectGenerator` is C# source generator is for ValueObjects (ie.Wrapper classes).

This project is under the develop🚧.

## Install

Under the develop.

## Usage

```csharp
using ValueObjectGenerator;

[IntValueObject]
public partial class ProductId
{
}
```

With `IntValueObject` attribute, below code is generated.

```csharp
public partial class ProductId: IEquatable
{
public int Value { get; }

public ProductId(int value)
{
Value = value;
}

public override bool Equals(object obj) => ReferenceEquals(this, obj) || obj is ProductId other && Equals(other);
public override int GetHashCode() => Value.GetHashCode();
public override string ToString() => Value.ToString();
public static bool operator ==(ProductId left, ProductId right) => Equals(left, right);
public static bool operator !=(ProductId left, ProductId right) => !Equals(left, right);

public bool Equals(ProductId other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Value == other.Value;
}

public static explicit operator ProductId(int value) => new ProductId(value);
public static explicit operator int(ProductId value) => value.Value;
}
```

`ProductId` is a `ValueObject` class (ie.Wrapper classes).

Below table shows all supporting Attributes and corresponding Types.

| attribute | type |
----|----
| StringValueObject | string |
| IntValueObject | int |
| LongValueObject | long |
| FloatValueObject | float |
| DoubleValueObject | double |

## Motivation

Next `Product` class has 2 int type properties, `ProductId` and `ProductCategoryId`.
Some methods need `ProductId` as an argument, the other methods need `ProductCategoryId` as an argument.
Sometime, developers may mistake between `ProductId` and `ProductCategoryId`.

```csharp
public class Product
{
public Product(string name, int productId, int productCategoryId)
{
Name = name;
ProductId = productId;
ProductCategoryId = productCategoryId;
}

public string Name { get; }
public int ProductId { get; }
public int ProductCategoryId { get; }
}
```

To avoid this mistake, we should create `ProductId` class and `CategoryId` class, and use them.
With these classes, compiler can detect wrong usage of `ProductId` property and `ProductCategoryId` property.

```csharp
public sealed class ProductId: IEquatable
{
public int Value { get; }

public ProductId(int value)
{
Value = value;
}

public override bool Equals(object obj) => ReferenceEquals(this, obj) || obj is ProductId other && Equals(other);
public override int GetHashCode() => Value.GetHashCode();
public override string ToString() => Value.ToString();
public static bool operator ==(ProductId left, ProductId right) => Equals(left, right);
public static bool operator !=(ProductId left, ProductId right) => !Equals(left, right);

public bool Equals(ProductId other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Value == other.Value;
}

public static explicit operator ProductId(int value) => new ProductId(value);
public static explicit operator int(ProductId value) => value.Value;
}

public class CategroyId: IEquatable
{
public int Value { get; }

public CategroyId(int value)
{
Value = value;
}

public override bool Equals(object obj) => ReferenceEquals(this, obj) || obj is CategroyId other && Equals(other);
public override int GetHashCode() => Value.GetHashCode();
public override string ToString() => Value.ToString();
public static bool operator ==(CategroyId left, CategroyId right) => Equals(left, right);
public static bool operator !=(CategroyId left, CategroyId right) => !Equals(left, right);

public bool Equals(CategroyId other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Value == other.Value;
}

public static explicit operator CategroyId(int value) => new CategroyId(value);
public static explicit operator int(CategroyId value) => value.Value;
}

public class Product
{
public Product(string name, ProductId productId, CategroyId productCategoryId)
{
Name = name;
ProductId = productId;
ProductCategoryId = productCategoryId;
}

public string Name { get; }
public ProductId ProductId { get; }
public CategroyId ProductCategoryId { get; }
}
```

There are many boilerplate code in `ProductId` and `CategoryId` classes. These boilerplate code is so noisy to read other important meaningful code.

`C# Source Generator` can generate these boilerplate code with smart way. `ValueObjectGenerator` generate ValueObject classes (ie.Wrapper classes) with `C# Source Generator`.

Below code is example of `ValueObjectGenerator`. There are no boilerplate code to create ValueObjects (ie.Wrapper classes ) like `ProductId` and `CategoryId` classes.

```csharp
[StringValueObject]
public class ProductName { }

[IntValueObject]
public class ProductId { }

[IntValueObject]
public class CategoryId { }

public class Product
{
public Product(ProductName name, ProductId productId, CategoryId productCategoryId)
{
Name = name;
ProductId = productId;
ProductCategoryId = productCategoryId;
}

public ProductName Name { get; }
public ProductId ProductId { get; }
public CategoryId ProductCategoryId { get; }
}
```

## Plans

* IComparable support.
* JSON serializer/deserializer.
* other value types.
* arithmetic operators support.

## Author

Ryota Murohoshi is game Programmer in Japan.

* Posts:http://qiita.com/RyotaMurohoshi (JPN)
* Twitter:https://twitter.com/RyotaMurohoshi (JPN)

## License

This library is under MIT License.