Question

I am passing 20+ arguments of different types to method. There should be some clean way to pass this. Can you please help me.

I can pass array of object having all these 20+ arguments but in target method I have to put checks on type. Is this good way to pass long list of arguments.

Code: Sample from code not full

private DataTable CreateDataTable(string[] args)
{
    DataTable dt = new DataTable();
    dt.Clear();

    foreach (var arg in args)
    {
    dt.Columns.Add(arg);
    }

    return dt;
}

I can pass array in this method because all arguments are of same type.

DataTable dt = CreateDataTable(new string[] { "ProjectId", 
                        "ParentProjectId", 
                        "ProjectName", 
                        "CreationDate");

Now here I have more than 20+ values of diff types like following

int projectId = 100;
int? parentProjectId = SomeCondition ? 10 : null;
string projectName = "Good Project"
DateTime createdDate = DateTime.Now;
.
.
.

In this method I would assign values to columns.

AssignValuesToDataTable(dt, Arguments list ......)
// Implementation would be like this. Here I am passing 20+ arguments.
private DataTable AssignValuesToDataTable(DataTable dt, arguments list ........)
{
    DataRow row = dt.NewRow();
    row["ProjectId"] = projectId;
    .
    .
    .

    dt.Rows.Add(row);
}

Can you please help. I am using C#4

EDIT:
Above code is an example from my real code but I am more interesting to know that what is best method to achieve this.

From Coding Horror (Jeff Atwood)

The more parameters a method has, the more complex it is. Limit the
number of parameters you need in a given method, or use an object to
combine the parameters.

Above quote is from this blog post.
Code Smells

Thanks.

Answer 1

Pass an object that represents the data instead:

private DataTable AssignValuesToDataTable(DateTable dt, Project project)
{
     row["ProjectId"] = project.Id;
     row["ProjectName"] = project.Name;
     ...
}

with

public class Project
{
    public int Id {get;set;}
    public string Name {get;set;}
    ...
}

of course, then the question becomes : why use DataTable at all? since a Project class is a much better metaphor / mechanism for expressing that data, and List<Project> (or BindingList<Project>) is ideal for a collection of such.

(hint: I very, very, very rarely use DataTable – or maybe less frequently than that)