CODEWITHSUNDEEP
c#
Alex
Alex

Reputation: 2335

C# reuse method and avoid disposing on using

I would like to optionally dispose (with a using statement) an object. If the connection string is passed in the constructor, then the using must dispose and if the object SQLDataLayer is passed in the constructor, then I don't want to dispose. This is to avoid passing the SQLDataLayer object in every re-usable method, is this the right approach?

public class RepoCategory
{
    readonly string connString;
    SQLDataLayer dl = null;

    public RepoCategory(string conn_string) 
    {
        this.connString = conn_string;
    }

    public RepoCategory(SQLDataLayer dl)
    {
        this.dl = dl;
    }

    //I WANT TO MAGICALLY generate using(null) if dl was passed in constructor
    //or using(dl = new SQLDataLayer(connString)) if connString was passed.
    public Category Get(int category_sid)   
    {
        Category cat = null;
        using (SQLDataLayer dlDispose = (dl == null) ? new SQLDataLayer(connString) : null)
        {
            //can this be simplified/avoided?
            if (dlDispose != null)
                dl = dlDispose;
            cat = dl.GetCat();                    
        }
        return cat;
    }
    //I DON'T WANT TO PASS THE DL MANUALLY EVERYTIME
    public Category Get(SQLDataLayer dl, int category_sid)
    {
        Category cat = null;
        cat = dl.GetCat();                    
        return cat;
    }   
}

thanks!

Upvotes: 0

Views: 146

Answers (3)

Ben Voigt
Ben Voigt

Reputation: 283674

In your particular example, like this:

SQLDataLayer dlDispose = null;
SQLDataLayer dl = this.dl ?? (dlDispose = new SQLDataLayer(connString));
using (dlDispose) { dl.Blah(...) }

This also fixes the bug where you leave the class field referring to a short-lived connection that you're also disposing.

For more general usefulness, it is helpful to have a holder class that implements Dispose and will conditionally call Dispose on the object it holds.

Upvotes: 0

SLaks
SLaks

Reputation: 887453

You don't need to declare variables in a using statement. You can make a using statement that only does anything in some circumstances:

SQLDataLayer dl = ...;
using(someCondition ? dl : null) {
    ...
}

Upvotes: 0

pm100
pm100

Reputation: 50190

using is just short hand for

try
{
  obj = new Obj();

}
finally
{ 
   obj.Dispose();
}

You can call Dispose directly if you want. Just do try / finally and in the finally go if(xxx) obj.Dispose()

Upvotes: 1

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