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In a notebook, I can easily search an expression for a custom symbol.

In[237]:= Position[{mySym, 1, 2}, mySym]
Out[237]= {{1}}

However, if I write a function and place it within a package;

FindSym[x_] := Position[x, mySym]

In[234]:= Clear@"PA`"
<< PA`
PA`Private`FindSym[{mySym, 1, 2}]
Out[236]= {}

The symbol can no longer be found. However, if instead of searching on a symbol, I search on a literal (string or number) or even a built-in name, the package version works.

I feel I'm missing something subtle. If anybody could give me pointers, I would be grateful.

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1 Answer 1

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If you literally have

FindSym[x_] := Position[x, mySym]

in your package, then this mySym is probably created in PA`Private` (depending on your package setup). PA`Private`mySym is distinct from Global`mySym . You were searching for the former when only the latter was present.

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  • $\begingroup$ Doh! I felt it was something like that. Thank you Szabolcs. $\endgroup$ Sep 23, 2021 at 9:02

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