What is a drawback of such a variable, say for multithreading,

If it is read-only. Ie. just conveying some piece of static information from the main program to the modules/threads, there is no significant problem.

If it is intended to act as a conduit for passing dynamic information back and forth between threads, then you would need to apply locking.

In general, there is no difference between obtaining a piece of static information from a global variable, and calling a (global) function (singleton instantiator) to obtain that information. Both involve the calling code "knowing" an well-known name.

Eg. $My::Config::DBhandle->somemethod( ... );

or My::Config->new()->get_DBHandle()->somemethod( ... );

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
RIP an inspiration; A true Folk's Guy

In reply to Re: globally seen vairable by BrowserUk
in thread globally seen vairable by vit

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