Where should global variables be defined in a package?

Question

I am trying to understand two of the answers to the question 114769 Package functions and symbolic calculations

    ClearAll["MyP`*"];
BeginPackage["MyP`"];
Global`b;
MyLagrange;
Begin["Private"];
MyLagrange[f_, var_] := Module[{a}, a = D[f, var] + b;
   a];
End[];
EndPackage[];
b = 17; MyLagrange[Sin[x1], x1]

returns

MyP`Private`b + Cos[x1]

so the Global statement has been ignored

score 7 · Accepted Answer · answered Dec 30 '23 at 18:45

You could explicitly use Global`b in the definition of MyLagrange:

ClearAll["MyP`*"];
BeginPackage["MyP`"];
MyLagrange;
Begin["Private"];
MyLagrange[f_, var_] := Module[{a}, a = D[f, var] + Global`b; a];
End[];
EndPackage[];
b = 17; MyLagrange[Sin[x1], x1]
(* 17 + Cos[x1] *)

Where should global variables be defined in a package?

1 Answers1