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37 :: Need help in macros/templates for class declarations etc.

• exhu (orginal) [2012-06-15T12:06:39+02:00] view original

  Ok, i've played much with templates and macros and still don't understand it well. It's better to start from very simple things and even here I need your help. I'll express the idea in a non-compilable code. Would you please correct me?

  E.g. If I want to declare classes like this:

  declClass(MyClassName, baseClass):

  fields

  How can I adjust the following code or do I need a macro?

  template declClass(clsName : expr, baseCls : expr, fields : stmt) : stmt =

  type

  P clsName* = ref T clsName

  T clsName* = object of baseCls

  fields

  proc new clsName() : P clsName =

  var o : P clsName new(o) return o

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• exhu (orginal) [2012-06-15T22:31:09+02:00] view original

  Actually solved: http://penguins-diary.blogspot.com/2012/06/nimrod-macro.html

  but "nimrod doc" command does not generate info about the classes defined by macros :(

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• Araq (orginal) [2012-06-15T22:39:18+02:00] view original

  Yes and a very good point, but next versions of "nimrod doc" will use the semantic checking and thus generate info about the classes defined by macros. ;-)

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• exhu (orginal) [2012-06-16T09:06:48+02:00] view original

  by the way, what does the second argument to newNimNode() means? it's default value is nil. I haven't figured it out, simply ignored and it worked.

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• Araq (orginal) [2012-06-17T10:39:42+02:00] view original

  If it's not nil, its line information is used for the newly created node, so it can be used to track where a node came from. I don't consider this API to be stable...

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• Araq (orginal) [2012-06-24T14:40:11+02:00] view original

  Good news: The latest github version supports a new doc2 command that produces the documentation after macro expansion. Please try it out.

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• exhu (orginal) [2012-06-24T19:03:22+02:00] view original

  Just tested doc2, works perfectly well!!! Thanks!

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• exhu (orginal) [2012-06-24T21:56:54+02:00] view original

  BTW is 'doc2' command experimental or it is 'doc' that will be tweaked in the future?

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• Araq (orginal) [2012-06-24T22:20:11+02:00] view original

  Both are here to stay. In the long run doc may become deprecated, but since they share most of the code it's no burden to maintain both. I plan to make doc2 generate much more cross references and and a "show implementation" feature.

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• adrianv (orginal) [2012-07-26T15:53:19+02:00] view original

  @exhu

  thanks for your example. It helped me to get started with nimrod macros. I changed your code a little, so that it works with the new ref object type and more than one line of member variables:

  https://github.com/AdrianV/nimrod-tools/blob/master/oopExample2.nim

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• exhu (orginal) [2012-07-26T20:06:04+02:00] view original

  @adrianv

  Thanks! Glad it was useful not only to me.

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