[SerializableAttribute]
public class AttributeDictionary : Dictionary<string, string>

[SerializableAttribute]
public class AttributeDictionary : Dictionary<string, string>

<SerializableAttribute> _
Public Class AttributeDictionary _
	Inherits Dictionary(Of String, String)

<SerializableAttribute> _
Public Class AttributeDictionary _
	Inherits Dictionary(Of String, String)

[SerializableAttribute]
public ref class AttributeDictionary : public Dictionary<String^, String^>

[SerializableAttribute]
public ref class AttributeDictionary : public Dictionary<String^, String^>

attr1=val1;attr2=val2;...attrN=valn

attr1=val1;attr2=val2;...attrN=valn

FillGrid(dataGridView, flatList); // fill DataGridView
flatList = GridToString(dataGridView); // extract from DataGridView

FillGrid(dataGridView, flatList); // fill DataGridView
flatList = GridToString(dataGridView); // extract from DataGridView

string flatList = "aaa=1;bbb=2";
AttributeDictionary dict = new AttributeDictionary(flatList);
dict["aaa"] = "5";
dict["bbb"] = "xyz";
dict["c"] = "new item here";
flatList = dict.ToString();
// result will be "aaa=5;bbb=xyz;c=new item here"

string flatList = "aaa=1;bbb=2";
AttributeDictionary dict = new AttributeDictionary(flatList);
dict["aaa"] = "5";
dict["bbb"] = "xyz";
dict["c"] = "new item here";
flatList = dict.ToString();
// result will be "aaa=5;bbb=xyz;c=new item here"

The utility of the above technique may not be immediately obvious, though I have found it useful in a variety of situations. The scenario that will be relevant to almost every developer is that of a ConnectionString. A typical ConnectionString might be stored in your Settings file as Data Source=SQL1X5;Initial Catalog=MyDbName;Persist Security Info=True, which is precisely an attribute string that AttributeDictionary is designed to handle. What you should probably not store in a ConnectionString are the User ID and Password attributes, though they need to be added. So here is the previous example rewritten in a ConnectionString context:

AttributeDictionary dict = new AttributeDictionary(myConnString);
dict["User ID"] = "username";
dict["Password"] = "open_sesame";
connection = new SqlConnection(dict.ToString());

AttributeDictionary dict = new AttributeDictionary(myConnString);
dict["User ID"] = "username";
dict["Password"] = "open_sesame";
connection = new SqlConnection(dict.ToString());

The above discussion handles a single-valued attribute list. AttributeDictionary also handles multi-valued attribute lists when working with a DataGridView. Consider that the single-valued attribute list could be viewed as a table with just one row. The attribute names are the column names, and the attribute values are the values in the single row. (Recall that the above talked about a DataGridView with 2 columns. Here we have just transposed that table (columns become rows) and subsumed the attribute names into the column headers.) A multi-valued attribute list, then, allows you to have multiple rows in this table. A multi-valued attribute list is stored into a DataGridView with exactly the same method call as a single-valued list shown above:

FillGrid(dataGridView, flatList);

FillGrid(dataGridView, flatList);

attr1[0]=val;attr2[0]=val;...attrN[0]=val;
attr1[1]=val;attr2[1]=val;...attrN[1]=val;
. . .
attr1[m]=val;attr2[m]=val;...attrN[m]=val

attr1[0]=val;attr2[0]=val;...attrN[0]=val;
attr1[1]=val;attr2[1]=val;...attrN[1]=val;
. . .
attr1[m]=val;attr2[m]=val;...attrN[m]=val

flatList = GridToString(dataGridView);

flatList = GridToString(dataGridView);

Since CleanCode 0.9.07.