Lambda .Where() expression to return selected/flagged objects

In our software we enable certain features based on the existence of a flag. The Flags class is a static class used to determine the existence of such a flag.

I came across one piece of logic that I wrote that I feel could benefit from refactoring. The boolean logic works, but I think it's difficult to understand or read because it relies very heavily on short-circuiting.

The basic logic is:

• Get all menu items.

• Return a subset of those menu items by using the following rule:

• Some menu items are tied to a specific flag that is expected to be hard-coded in some way. The menu item name may not match the associated flag.

• Any other menu items should be displayed.

Any help would be much appreciated.

private IEnumerable GetMenuItems()
{
     return GetAllMenuItems().Where(mi => 
          (mi.MethodName != "NewWidget" || Flags.HasFlag("Feature1")) &&
          (mi.MethodName != "NewDongle" || Flags.HasFlag("Feature2")));
}

If you control the MenuItemDefinition class, why not just add a feature tag to it?

public class MenuItemDefinition
{
    public string MethodName { get; set; }
    public string Feature { get; set; }
}

// each instance
new MenuItemDefinition { MethodName = "NewWidget", Feature = "Widgets" }

// GetMenuItems():
return GetAllMenuItems().Where(m => FeatureIsEnabled(m.Feature));

If not, you could put them in a dictionary:

var items = new Dictionary {
    { "Widgets", new[] {
        new MenuItemDefinition { MethodName = "NewWidget" },
        new MenuItemDefinition { MethodName = "DeleteWidget" }
    },
    { "Default", new[] {
        // ....
    }
}

return items.Where(pair => FeatureIsEnabled(pair.Key)).SelectMany(pair => pair.Value);

Or better yet, build the initial list based upon content in a dictionary. That way you don't run the risk of having typos in the switch or the initial setup:

var dict = new Dictionary 
{
    { "Widgets", new[] { "NewWidget", "DeleteWidget" },
    { "Default", new[] { "..." }
    ...
}

var menuItems = dict
    .Where(p => FeatureIsEnabled(p.Key))
    .SelectMany(p => p.Value)
    .Select(mn => new MenuItemDefinition { MethodName = mn });

// GetMenuItems()
return menuItems; // :)

StackExchange Code Review Q#8264, answer score: 3