You could use 

{
    local $SIG{__WARN__} = sub { ... };
    eval { ... };
}

[download]

to trap the warning and do something special with it. However, I can't see that helping with identifying uninitialised values.

There's example code in perlvar: %SIG.

— Ken

In reply to Re^4: determine the variable causing the error: Use of uninitialized value by kcott
in thread determine the variable causing the error: Use of uninitialized value by ruqui

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