Generic way of writing this enum code?

[codefragment]

Hi
The methods below are identical except they take as arguments
different enum types.
There must be a better way of writing this?

ta


public string ConcatValues(params EnumType1 [] types)
{
StringBuilder sb = new StringBuilder();
bool first = true;
foreach (EnumType1 type in types)
{
if (first)
{
first = false;
}
else
{
sb.Append(",");
}
sb.Append((int)type);
}

return sb.ToString();
}

public string ConcatValues(params EnumType2 [] types)
{
StringBuilder sb = new StringBuilder();
bool first = true;
foreach (EnumType2 type in types)
{
if (first)
{
first = false;
}
else
{
sb.Append(",");
}
sb.Append((int)type);
}

return sb.ToString();
}

etc

 

[Nicholas Paldino [.NET/C# MVP]]

You can use generics to do this:

public string ConcatValues<T>(params T[] types)
{
// Check to make sure that T is an enumeration.
if (!typeof(T).IsEnum)
{
// Throw an exception.
throw new InvalidOperationException("The type parameter T must be an
enumeration type.");
}

// Create the string builder.
StringBuilder sb = new StringBuilder();

foreach (T type in types)
{
// Append.
sb.Append((int) type);
sb.Append(",");
}

// Remove the comma, if necessary.
if (sb.Length > 0)
{
// Remove the comma.
sb.Remove(sb.Length - 1, 1);
}

// Return the string.
return sb.ToString();
}

Note that you have to check to make sure that the type T is an
enumeration at runtime, since the compiler will not allow you to create a
constraint against System.Enum (which all enumerations derive from).

 

[Brendon Bezuidenhout]

Hey,

Just add a GenericType and change your EnumTypes1[] to the generic type and
access them that way -

<code>
public string ConcatValues<GenericType>(params GenericType[] types)
{

}
</code>

You might also be interested in:
Generic Parameters :
http://msdn2.microsoft.com/en-us/library/0zk36dx2(VS.80).aspx
Generics : http://msdn2.microsoft.com/en-us/library/512aeb7t(VS.80).aspx

HTH
Brendon

 

[Ben Voigt [C++ MVP]]

You can use generics to do this:

public string ConcatValues<T>(params T[] types)
{
// Check to make sure that T is an enumeration.
if (!typeof(T).IsEnum)
{
// Throw an exception.
throw new InvalidOperationException("The type parameter T must be
an enumeration type.");
}

// Create the string builder.
StringBuilder sb = new StringBuilder();

foreach (T type in types)
{
// Append.
sb.Append((int) type);

This line won't compile, because there's no constraint making T convertible
to an integer. Add a constraint "where T : IConvertible" and use
"type.ToInt32(null)".

sb.Append(",");
}

// Remove the comma, if necessary.
if (sb.Length > 0)
{
// Remove the comma.
sb.Remove(sb.Length - 1, 1);
}

// Return the string.
return sb.ToString();
}

Note that you have to check to make sure that the type T is an
enumeration at runtime, since the compiler will not allow you to create a
constraint against System.Enum (which all enumerations derive from).


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Hi
The methods below are identical except they take as arguments
different enum types.
There must be a better way of writing this?

ta


public string ConcatValues(params EnumType1 [] types)
{
StringBuilder sb = new StringBuilder();
bool first = true;
foreach (EnumType1 type in types)
{
if (first)
{
first = false;
}
else
{
sb.Append(",");
}
sb.Append((int)type);
}

return sb.ToString();
}

public string ConcatValues(params EnumType2 [] types)
{
StringBuilder sb = new StringBuilder();
bool first = true;
foreach (EnumType2 type in types)
{
if (first)
{
first = false;
}
else
{
sb.Append(",");
}
sb.Append((int)type);
}

return sb.ToString();
}

etc

 

[codefragment]

Yep, thanks for all the replies. I've put the code in and its working
happily