Collecting the better-late-then-never award:

Look for the module in the %INC associative array. According to the docs for require (and use just calls require in a BEGIN block) every module that gets 'used' gets its name put into this hash, where the key is the file name, and the value is the 'real path' to the file. So the answer is: 

if( not exists $INC{DBI} )
{
    require DBI;
}

[download]
Update: Noticing that KM actually gave this answer here, I return the "better-late-then-never" award. Sigh.

In reply to RE: Detecting modules in use? by Adam
in thread Detecting modules in use? by BBQ

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