I'm planning to have a Package variable that is a hash, say %BigHash, that I will create only if it is needed. Perhaps I'll read it in from another file.

A hash can't be undef like a scalar can. What's an efficient and elegant way to test to see if I've loaded it already? If I used a ref instead of a hash variable, I could use undef as opposed to a hash ref. But I plan to make the thing available as a public variable too, and there's really no need for it to be a reference other than this feature.

If it's not defined at all, I should be able to check for exists in the Stash, right? Is that efficient, like checking the keys of a regular hash? I'm just curious at this point, since I suppose that even so, it's only as efficient as a hash exists, while normal named variables are even more efficient.

So my current plan is to use a separate lexical variable to keep track of whether it's been loaded, since that is fastest to check. But it bugs me to use a separate variable, and I still wonder if there is a better (or at least "cooler") way.

In reply to lazy creation of a hash by John M. Dlugosz

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