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crystal-lang

Sharing variables between different macros

How to access vars in macro that are set in another macro e.g.

macro foo(arg)
 {% SHARED_VAR = arg%}
 p {{arg}}
end

macro baz

 p {{ SHARED_VAR }}

end

foo("foo")
baz #=> prints "foo"
Solution

  • Well, this is just not a feature of the language, and probably for good reasons.

    Some alternatives:
    Use a constant instead, but you cannot do compile-time things with it:

    macro foo(arg)
  SHARED_VAR = {{arg}}
end

macro baz
  p SHARED_VAR
end

foo("foo")
baz #=> prints "foo"

    Or simply call the other macro with the additional information:

    macro foo(arg)
  {% shared_var = arg %}
  baz({{shared_var}})
  p {{arg}}
end

macro baz(arg)
  p {{arg}}
end

foo("foo") #=> prints "foo"