This week in PeanutButter

Ok, so I'm going to give this a go: (semi-)regularly blogging about updates to PeanutButter in the hopes that perhaps someone sees something useful that might help out in their daily code. Also so I can just say "read my blog" instead of telling everyone manually ^_^

So this week in PeanutButter, some things have happened:

• DeepEqualityTester fuzzes a little on numerics -- so you can compare numerics of equal value and different type correctly (ie, (int)2 == (decimal)2). This affects the {object}.DeepEquals() and PropertyAssert.AreDeepEqual() methods.
• DeepEqualityTester can compare fields now too. PropertyAssert.DeepEquals will not use this feature (hey, the name is PropertyAssert!), but {object}.DeepEquals() will, by default -- though you can disable this.
• DuckTyper could duck Dictionaries to interfaces and objects to interfaces -- but now will also duck objects with Dictionary properties to their respective interfaces where possible.
• String extensions for convenience:
• ToKebabCase()
• ToPascalCase()
• ToSnakeCase()
• ToCamelCase()
• DefaultDictionary<TKey, TValue> - much like Python's defaultdict, this provides a dictionary where you give a strategy for what to return when a key is not present. So a DefaultDictionary<string, bool> could have a default value of true or false instead of throwing exceptions on unknown keys.
• MergeDictionary<TKey, TValue> - provides a read-only "view" on a collection of similarly typed IDictionary<TKey, TValue> objects, resolving values from the first dictionary they are found in. Coupled with DefaultDictionary<TKey, TValue>, you can create layered configurations with fallback values.
• DuckTyping can duck from string values to enums

And I'm quite sure the reverse (enum to string) will come for cheap-or-free. So there's that (: You might use this when you have, for example, a Web.Config with a config property "Priority" and you would like to end up with an interface like:

public enum Priorities
{
  Low,
  Medium,
  High
}
public interface IConfig
{
  Priorities DefaultPriority { get; }
}

And a Web.Config line like:

<appSettings>
  <add key="DefaultPriority" value="Medium" />
</appSettings>

Then you could, somewhere in your code (perhaps in your IOC bootstrapper) do:

 var config = WebConfigurationManager.AppSettings.DuckAs<IConfig>();

(This already works for string values, but enums are nearly there (:). You can also use FuzzyDuckAs<T>(), which will allow type mismatching (to a degree; eg a string-backed field can be surfaced as an int) and will also give you freedom with your key names: whitespace and casing don't matter (along with punctuation). (Fuzzy)DuckAs<T>() also has options for key prefixing (so you can have "sections" of settings, with a prefix, like "web.{setting}" and "database.{setting}". But all of that isn't really from this week -- it's just useful for lazy devs like me (: