Automatic Properties and Values Types Don’t Mix

Consider the following struct:

public struct BirthDate
{
  private DateTime value;
    
  public BirthDate(DateTime value)
  {
    this.value = value;
  }
    
  public override string ToString()
  {
    return this.Value.ToString();
  }

  public DateTime Value
  {
    get
    {
      return this.value;
    }
  }
}

This works just fine.

Now let’s make our life easier by refactoring to use automatic properties:

public struct BirthDateWithAutomaticProperties
{
  public BirthDateWithAutomaticProperties(DateTime value)
  {
    this.Value = value;
  }

  public override string ToString()
  {
    return this.Value.ToString();
  }

  public DateTime Value
  {
    get;
    private set;
  }
}

Nope, this won’t compile:

Error 1 The 'this' object cannot be used before all of its fields are assigned to.

OK … let’s try this:

public struct BirthDateWithAutomaticProperties
{
  public BirthDateWithAutomaticProperties()
  {
    this.Value = DateTime.Now;
  }
    
  public BirthDateWithAutomaticProperties(DateTime value)
  {
    this.Value = value;
  }

  public override string ToString()
  {
    return this.Value.ToString();
  }

  public DateTime Value
  {
    get;
    private set;
  }
}

Nope:

Error 1 Structs cannot contain explicit parameterless constructors

Error 2 The 'this' object cannot be used before all of its fields are assigned to

Error 3 The 'this' object cannot be used before all of its fields are assigned to 

OK … well, I’m out of ideas. It doesn’t seem like automated properties play nicely with value types, unless I’m missing something (which is probably the case - I very rarely make a struct these days and I might be forgetting the obvious solution).

Published: 11.05.2008 02:54:40 PM CST

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Jason Bock

Automatic Properties and Values Types Don’t Mix