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Simplify C# with Expression-Bodied Members

quillcodes profile image QuillCodes Originally published at quill.codes ・2 min read

You Can Simplify Your Syntax

C# is a fantastic language because it constantly evolves in a way that simplifies syntax and makes the your code more expressive. Expression-bodied members were released in C# 6 and further enhanced in C# 7. At the time I was still a junior developer and had not yet decided that C# and .NET were going to be my long-term focus.

I am not going to say that this feature "sealed the deal" for me and .NET, but it's definitely the feature I miss most when using any other language.

Simple Expression-bodied Members

The simplest form is just to take any existing read-only property and condense it down.

public int MyProperty
{
  get 
  {
    return _myField;
  }
}
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This becomes:

public int MyProperty => _myField;
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You can even use it for simple method bodies:

public decimal CalculateTax(decimal rate) => _totalPrice * rate;
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It saves you time, and it saves you space on your screen. Most C# style conventions say that the opening bracket { and closing bracket } belong on new lines (with some exceptions). You could argue with the style guide, but on a larger team that is probably a losing battle. This feature solves this problem by omitting the brackets entirely.

Expression-bodied Members Can Help Reduce Boilerplate

Not impressed yet? What if I told you that you can use expression-bodied members on full properties?

private int _myField;

public int MyProperty 
{
  get => _myField; 
  set => _myField = value;  
}
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That is pretty nifty, but honestly not impressive unless you have logic to call on your getter/setter.

private int _myField;

private void SetField(ref int field, int value, [CallerMemberName]string memberName =  "")
{
  field = value;
  Console.WriteLine($"{memberName} was set to {value}.");
}

public int MyProperty
{
  get => _myField;
  set => SetField(ref _myField, value);
}

// Output for "MyProperty = 5"
// MyProperty was set to 5.
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Expression-Bodied Members Can be Used in Constructors

The most repetive boilerplate you tend to get with C# is setting class fields in constructors.

public class Cake
{
  private readonly IFrosting _frosting;

  public Cake(IFrosting frosting) => _frosting = frosting;
}
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This simplifies your single-assignment constructors greatly. However, you can also combine this with tuple syntax in order to perform multiple assignments at once.

public class Cake
{
  private readonly ISprinkles _sprinkles;
  private readonly IFrosting _frosting;

  public Cake(ISprinkles sprinkles, IFrosting frosting)
    => (_sprinkles, _frosting) = (sprinkles, frosting);
}
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This syntax will assign the fields in the order that they appear in the tuple.

Note: Keep in mind that if your parameters are all of similar types, like string, that getting them in the wrong order can be easy using this syntax. However, fields of different types will be caught by the compiles. Thus, I would only recommend it when assigning a set of varied fields.

Hope you enjoyed this quick overview of one of my favorite features of C#!

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