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Description

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= Provides a standardized mechanism for describing single-property values (like 'PhoneNumber' of 'Customer' for instance).0x000D0x000A0x000D0x000A(The difference between -ITypeDescriber- and -IP- is that the former must be stored 'inside' an -IP-.0x000D0x000AIn RDBMS-terms a -ITypeDescriber- is the Field stored within a -IP- which is the Post.)0x000D0x000A0x000D0x000AThe most important functionality usually provided is validation and parsing in a standardized manner.0x000D0x000A0x000D0x000AThis is done by a static method call 'EnrichKey' which is supposed to be available in a class 'implementing' this interface.0x000D0x000AIn this manner, types implementing this 'interface' is by this principle able to describe themselves to AgoRapide).0x000D0x000AFor a typical example, see -EnrichKey-.0x000D0x000A0x000D0x000ANote how this interface in itself is empty 0x000D0x000A(apart from -GetSyntaxHelp- which is just a suggestion to use in your implementing classes.)0x000D0x000A0x000D0x000ASee -Initialize- for where this 'interface' is actually used.0x000D0x000A0x000D0x000AEnrichKey should have the following signature:0x000D0x000A  public static void EnrichKey(PK k)0x000D0x000A0x000D0x000AA typical method will set -ValidatorAndParser- although other attributes of -PK- may also be changed (which gives rise to the somewhat strange name for the method 'EnrichKey').0x000D0x000A0x000D0x000A(note that for very common types like string, int, long, bool, DateTime, TimeSpan, Type, Uri and so on -PKTypeAttribute- provides a -StandardValidatorAndParser-.)0x000D0x000A0x000D0x000AA typical implementation can look like this:0x000D0x000A0x000D0x000A   public static void EnrichKey(PK k) 0x007B0x000D0x000A      k.SetValidatorAndParser(new Func0x003Cstring, ParseResult0x003E(value =0x003E0x000D0x000A        TryParse(value, out var retval, out var errorResponse) ?0x000D0x000A          ParseResult.CreateOK(retval) :0x000D0x000A          ParseResult.CreateError(errorResponse)0x003B0x000D0x000A      ))0x003B0x000D0x000A  0x007D0x000D0x000A0x000D0x000AThe typical TryParse method in the implementation class should follow the ordinary .NET pattern with the addition of a 'out string errorResponse' parameter which can communicate WHY the value was not valid for parsing. This helps a lot with error messages, making an API for instance much more user friendly.0x000D0x000A0x000D0x000ANote the the implementation class should also overrride object.ToString() to a format actually understood by the ValidatorAndParser returned. This is necessary for the storage mechanism, like -PropertyStream- to work (serialization and de-serialization of objects).

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