CODEWITHSUNDEEP
c#parametersreturnout
mihai
mihai

Reputation: 2824

Is it possible to use 'return' and 'out' the same time?

I have a method GetSelectedServices() which returns Selected Nodes from a Tree List, Expecting to return with the same method selected nodes and all Nodes i tried to add an out parameter.

But when I call this method i'm supposed to give the out parameter and so the returned list with selectedNodes is masked, and i cannot have it.

My Method

internal List<__ServiceInfo> GetSelectedServices(out List<__ServiceInfo> lstAll)
{
    List<__ServiceInfo> lstSelected = new List<__ServiceInfo>();
    List<__ServiceInfo> lstA = new List<__ServiceInfo>();

    foreach (TreeListNode node in this.tlServices.Nodes)
    {
        if (node.Checked)
        {
            var service = this.tlServices.GetDataRecordByNode(node) as __ServiceInfo;
            lstA.Add(service);

            if (service != null)
            {
                lstSelected.Add(service);
            }

            if (node.Nodes.Count > 0)
            {
                foreach (TreeListNode subNode in node.Nodes)
                {
                    if (subNode.Checked)
                    {
                        service = this.tlServices.GetDataRecordByNode(subNode) as __ServiceInfo;
                        lstA.Add(service);

                        if (service != null)
                        {
                            lstSelected.Add(service);
                        }
                    }
                }
            }
        }
    }
    lstAll = lstA;

    return lstSelected;
}

The way I call the method

public bool HasValidModel()
{
    List<__ServiceInfo> lstAll = new List<__ServiceInfo>();
    //here I get all nodes
    var allServices = this.GetAllServices(out lstAll);

    List<__ServiceInfo> lstSelected = new List<__ServiceInfo>();
    //but how to get the list from  ""return lstSelected"";
}

thank you for any suggestions.

Upvotes: 0

Views: 291

Answers (3)

Stefan
Stefan

Reputation: 14880

The way you implemented the return and the out parameter seems to be fine. But the call is wrong. @Ken's answer points in the right direction.

However the logic in the GetSelectedServices method is odd. The only difference between a "selected" service and a "regular" service is that a "regular" service is NULL. Which leads to the result that the allServices list is a collection of NULLs plus the selected services. Which makes no sense in my opinion.

Upvotes: 3

Ken Wayne VanderLinde
Ken Wayne VanderLinde

Reputation: 19347

Just use two variables, like this:

List<__ServiceInfo> lst;
List<__ServiceInfo> lstSelected = GetSelectedServices(out lst);

The 'return'ed object is now referenced by lstSelected, while the outed object is referenced by lst.

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1504182

You've already got two variables, although you're initializing one of them unnecessarily. Just use:

public bool HasValidModel()
{
    List<__ServiceInfo> lstAll;
    var selectedServices = this.GetAllServices(out lstAll);

    // Now use lstAll and selectedServices
}

Personally I don't really like using out parameters much, and would look for an alternative design if possible, but that's a separate matter. (I'd separate out finding all services from selecting some of them.)

Upvotes: 4

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