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9117 :: Program level variables

• archnim (orginal) [2022-04-19T09:56:12+02:00] view original

  Hello world. How can I create a variable (or constant) that is available across all the modules of a same program ? Is there an equivalent of Nodejs's Global object ?

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• Stefan_Salewski (orginal) [2022-04-19T10:01:32+02:00] view original

  You declare it at global scope, and attach the export marker, the asterisk * to it. But It will not be available automatically everywhere, you still have to import that symbol into all the modules that will use it.

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• archnim (orginal) [2022-04-19T10:03:16+02:00] view original

  OK. Thank you. I'm reading your book. What a pleasure ! Thank you very much for it.

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• PMunch (orginal) [2022-04-19T10:03:24+02:00] view original

  You can always but an exported global in a module and just import that everywhere. Otherwise you have to use a define I think, or patch it into the system module..

  Maybe more important is why you want a program level global.

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• archnim (orginal) [2022-04-19T10:06:32+02:00] view original

  By the way, I can bind a proc to a type, can I do the same thing with a var ? (an equivalent of static attributes in C++)

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• archnim (orginal) [2022-04-19T10:10:43+02:00] view original

  I want it to share state in real time between several modules, some of which launch threads. Anyway Importing a module containing the globals works fine in my case. I just wanted to know if there is an easier way that I ignored. Thanks.

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• Stefan_Salewski (orginal) [2022-04-19T10:14:12+02:00] view original

  I can bind a proc to a type,

  Sorry, I can not understand your question that well, maybe Mr. Munch can answer it, he is generally really good in understanding questions.

  I guess with "bind a proc to a type" you are referring to https://ssalewski.de/nimprogramming.html#_procedures_bound_to_a_data_type?. That is not used that often, but maybe with a similar construct you may access variables?

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• archnim (orginal) [2022-04-19T10:27:01+02:00] view original

  you are referring to https://ssalewski.de/nimprogramming.html#_procedures_bound_to_a_data_type

  Exactly. But as you said, it's not a current method in Nim.

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• shirleyquirk (orginal) [2022-04-19T10:54:39+02:00] view original

  If you mean a static member sure you can emulate that:

  type Foo* = object
  var fooBar = 9
  proc bar*(t: typedesc[Foo]):int = fooBar
  
  echo Foo.bar
  Run

  with the global unexported and the getter exported, and ufcs

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• PMunch (orginal) [2022-04-19T20:49:54+02:00] view original

  The global pragma can also be used for similar behavior to static class members in C++.

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