Jira (PUP-5844) Add the Object type to the Puppet Type system

[Thomas Hallgren (JIRA)]

Title: Message Title

Thomas Hallgren commented on PUP-5844   Re: Add the Object type to the Puppet Type system My first though was that this can be made even simpler. Let's control optionality with a single assignment operator. Everywhere! We already have it in parameter expressions. Things are more complex than that but in general, the following should work for most cases (using simple String type throughout to avoid clutter): type MyType = Object[{ a => String, # must be provided b => Undef[String], # must be provided, but undef is allowed c => String = 'x', # will have the value 'x' unless provided d => Undef[String] = undef # will have the value undef unless provided }] Unfortunately, the world is more complex and there are several additional things that we will want to consider: Be able to describe the difference between an entry that has its default value and a truly optional entry (will not be instantiated unless provided). Be able to describe if the type will allow additional entries in an instance or if that is considered a mismatch. If one entry, or a combination of entries, forms a unique key (hash and == must be based on this). Default sort order (for the <=> operator) Tell if instances of this type are iterable. Combined factors that is needed for successful validation. Since none of these complicating factors can be described as traits on the value type of an entry, and some not even as traits on the entry itself, we need an additional hash where we describe traits that the Struct or Object has in addition to its entries. Once we have that, we might just as well move everything to that hash, including the default values: type MyType = Object[{ a => String, b => Undef[String], c => String, d => Undef[String] },{ defaults => { c => 'x' }, # c will have the value 'x' unless provided optional => [d], # d will not exist unless provided additional => false, # additional elements is considered a mismatch unique => [ a, b ], # the combination of a and b forms a unique key iterable => false, # not iterable validation => function($value) {} # Additional validation of a value }] Here the concerns are separated in a clean way. The first hash described the entries with just name and type, the second describes additional object traits. We might want to add more to this hash to describe how instances should be ordered , etc. Add Comment   This message was sent by Atlassian JIRA (v6.4.12#64027-sha1:e3691cc) -- You received this message because you are subscribed to the Google Groups "Puppet Bugs" group. To unsubscribe from this group and stop receiving emails from it, send an email to puppet-bugs+unsubscr...@googlegroups.com. To post to this group, send email to puppet-bugs@googlegroups.com. Visit this group at https://groups.google.com/group/puppet-bugs. For more options, visit https://groups.google.com/d/optout.