Is there a way in Crystal to import a class or method from a file with a given prefix (as if said objects (class, method, variable) were defined in a given Module)? For instance, how could I invoque say mathematical functions (sin(), cos()) from an hypothetical external math file as math.sin() math…

No Crystal doesn’t have anything like this. Ideally library authors would namespace their types/methods, e.g. https://crystal-lang.org/api/Math.html as opposed to just defining things on the top level that may conflict with other types/methods. Also see Modules - Crystal .

Thanks! Is there perhaps a workaround with macros?

A means to import (require), say, a method m1(), for instance, alternatively as: m1() or as myFile.m1() regardless of modules, depending upon cases where conciseness is a priority or cases where clarity (explicit belonging of a function to a file) is considered a priority. Example from Go: imp…

There’s no way to do that. On the other hand, most methods in a library are instance methods, so the times where you do need to call a module function are pretty rare.

If you’re only talking about the Math module itself, that module already extends itself, so you can already call Math.sin(), Math.cos(), etc… That way you know those are methods on that module. As for other modules, you do something similar depending on how you have things setup. Open the module, e…

Thanks. But conversely, I assume I cannot require “math” and discard the Math prefix, all I can do is make it shorter, as in: require "math" m = Math puts "cos(0) = #{m.cos(0)}" But there in no built-in mechanism to call, say the cos method, without any prefix, _I guess?

You can do include Math, but that makes those methods available everywhere. There was a proposal for private include but it never happened

Imports (require)

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serge-hulne April 3, 2021, 9:11pm 7

Thanks.

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Imports (require)

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