C# Object Constructor Overloads

Question

I'm trying to have an overloaded constructor for a class. I think this should be fairly simple, however I can't seem to make it work.

Any ideas?

    public SaveFile(string location)
    {
        // Constructor logic here
        //TODO: Implement save event.
        this.Save(location);
    }

    public SaveFile()
    {
        string location = Environment.GetFolderPath(Environment.SpecialFolder.Personal) + "\\SaveFile.DAT";
        SaveFile(location);
    }

This doesn't compile correctly, and I can't figure out how to do make it work.

"This doesn't compile correctly" what error are you getting? — Juliet
– Juliet, Commented Feb 11, 2010 at 1:01
Others have addressed the specific issue of chaining constructors. What I would like to add is a design critique. It feels very wrong to be calling a Save() method from a constructor. Constructors should really do as little as possible other than initializing the object. — Josh
– Josh, Commented Feb 11, 2010 at 1:08
Sorry I didn't specify earlier. The Class is named SaveFile. It's just a serializable form of the data structure. — WedTM
– WedTM, Commented Feb 11, 2010 at 1:20

mskfisher · Accepted Answer · 2011-11-08 21:45:21Z

6

You have the wrong syntax for calling an overloaded constructor from within the default constructor.
To call an overloaded constructor in the same class, use this syntax:

public ClassName(parameters) : this(otherParameters)
{
   // logic
}

If you wanted to call a constructor in the base class, then you would use the base keyword instead of this. In your case the code would read:

public SaveFile() : this(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "SaveFile.DAT") {}
public SaveFile(string location)
{
    this.Save(location);
}

edited Nov 8, 2011 at 21:45

mskfisher

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answered Feb 11, 2010 at 1:01

Kasper Holdum

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1 Comment

WedTM Over a year ago

See! I knew it was something simple that I was missing!

James Curran · Accepted Answer · 2010-02-11 01:04:32Z

2

 public SaveFile() 
   : this(Environment.GetFolderPath(Environment.SpecialFolder.Personal) + "\\SaveFile.DAT")
    { 
    }

However that really should be:

 public SaveFile() 
   : this(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal),"SaveFile.DAT"))
    { 
    }

answered Feb 11, 2010 at 1:04

James Curran

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Comments

gilbertc · Accepted Answer · 2010-02-11 01:03:08Z

1

Try this

public SaveFile(string location)
{
    // Constructor logic here
    //TODO: Implement save event.
    this.Save(location);
}

public SaveFile(): this(Environment.GetFolderPath(Environment.SpecialFolder.Personal) + "\\SaveFile.DAT")
{
}

answered Feb 11, 2010 at 1:03

gilbertc

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