创建通用方法

Question

I am here wanted to implement some methods that coverts a list of interface references to their respective class type and then return the list is unique in some sense.

Here is the

    public bool IsFilesHavingUniqueID(List<IFile> files)
    {
        List<File> _files = files.ConvertAll(x => (File)x).ToList();
        return _files.Distinct().ToList().Count == _files.Count; 
    }

    public bool IsTablesHavingUniqueID(List<ITable> tables)
    {
        List<Table> _tables = tables.ConvertAll(x => (Table)x).ToList();
        return _tables.Distinct().ToList().Count == tables.Count;
    }

Calling of these methods

    public bool ValidateDIPObject(DIP dip)
    {
        // Validating Tabels
        IsFilesHavingUniqueID(dip.Files);

        // Validating Files
        IsTablesHavingUniqueID(dip.Tables);

        // ... continues 
    }

Is there any method I can write this code in a generic way. I have to write a bunch of methods with the same pattern so I think generic code will be the best option.

Please help

Answer 1

You could do this:

public bool IsUnique<IView,T>(List<IView> ls) where T : class
{
    return ls.Cast<T>().Distinct().Count()==ls.Count();
}

Answer 2

You can simply specify type and interface as generic parameters:

public bool IsTablesHavingUniqueID<TInterface, T>(List<TInterface> tables)
       where T:TInterface
{
    List<T> _tables = tables.ConvertAll(x => (T)x).ToList();
    return _tables.Distinct().ToList().Count == tables.Count;
}

This code assumes class correctly implements IEquatable<T> , GetHashCode and
Equals , if not - use other overrides of Distinct that take comparers.

Note that code looks like partially incorrect implementation of OfType and possibly code can be re-written as:

    tables.OfType<File>().Distinct().Count() == tables.Count();