The symbol table consists of a hierarchy of globs. A glob, short for typeglob, is a structure that has a slot for each variable type supported by Perl (and a few more). By using a glob for each symbol in the symbol table, we can have variable of each type with the same name.

• Scalar ($foo)
• Array (@foo)
• Hash (%foo)
• Sub (&foo)
• File handle
• Dir handle
• Format
• etc

$ftp is expected to be a glob. (Probably so it can be used as a file handle.)

---

${*$ftp}{net_ftp_host}
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can also be written as

$ftp->**->{net_ftp_host}
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which is equivalent to

$ftp->*{HASH}->{net_ftp_host}
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But it's not equivalent to

$ftp->{net_ftp_host}   # XXX
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The program is accessing the HASH slot of the glob, which contains a reference to a hash with the object's attributes.