//----< write details of element with enumerable Data to string >------
public static string showElement <Key, Data, T>(this DBElement <Key, Data> elem)
where Data : IEnumerable <T> // constraint clause
{
StringBuilder accum = new StringBuilder();
accum.Append(elem.showMetaData());
if (elem.payload != null)
{
IEnumerable <object> d = elem.payload as IEnumerable <object>;
if (d == null)
{
accum.Append(String.Format("\n payload: {0}", elem.payload.ToString()));
}
else
{
bool first = true;
accum.Append(String.Format("\n payload:\n "));
foreach (var item in elem.payload) // won't compile without constraint clause
{
if (first)
{
accum.Append(String.Format("{0}", item));
first = false;
}
else
{
accum.Append(String.Format(", {0}", item));
}
}
}
}
return(accum.ToString());
}
//----< write details of element with simple Data to string >----------
public static string showElement <Key, Data>(this DBElement <Key, Data> elem)
{
StringBuilder accum = new StringBuilder();
accum.Append(elem.showMetaData());
if (elem.payload != null)
{
accum.Append(String.Format("\n payload: {0}", elem.payload.ToString()));
}
return(accum.ToString());
}
static void Main(string[] args)
{
"Testing DBExtensions Package".title('=');
WriteLine();
Write("\n --- Test DBElement<int,string> ---");
DBElement <int, string> elem1 = new DBElement <int, string>();
elem1.payload = "a payload";
elem1.children = new List <int> {
1, 2, 3, 4
};
Write(elem1.showMetaData <int, string>());
DBEngine <int, DBElement <int, string> > dbs = new DBEngine <int, DBElement <int, string> >();
dbs.insert(1, elem1);
dbs.show <int, DBElement <int, string>, string>();
WriteLine();
Write("\n --- Test DBElement<string,List<string>> ---");
DBElement <string, List <string> > newelem1 = new DBElement <string, List <string> >();
newelem1.name = "newelem1";
newelem1.descr = "test new type";
newelem1.children = new List <string> {
"Key1", "Key2"
};
newelem1.payload = new List <string> {
"one", "two", "three"
};
Write(newelem1.showElement <string, List <string>, string>());
DBEngine <string, DBElement <string, List <string> > > dbe = new DBEngine <string, DBElement <string, List <string> > >();
dbe.insert("key1", newelem1);
dbe.show <string, DBElement <string, List <string> >, List <string>, string>();
Write("\n\n");
}