Please use typeglob not glob in future to avoid confusion with the glob function. Perl typeglobs have a notoriously obscure syntax. They are rarely used in high-level user code. They are often used in low level system code and when building tools. Some background and references:

• Mastering Perl (Chapter 8: Symbol Tables and Typeglobs) by brian d foy
• What are typeglobs (useful for)?
• Why does Perl have typeglobs?
• Referencing localized variables, and typeglobs by haukex

• typeglob in perlglossary
• Symbol (perldoc Symbol)

Though I've used typeglobs occasionally, for example in an automated testing hack to verify a file being used by a module contained the expected content, their syntax always does my head in. That I'm no typeglob expert is proved by not finding Ton's famous winning typeglob hack, despite hacking away for a whole week in Christmas 2006. :)

• Dueling Flamingos: The Story of the Fonality Christmas Golf Challenge (Ton Hospel wins a big Perl golf tournament by finding a typeglob hack)

References added later:

• The Symbol Table Describes Itself: examples comparing Perl, Raku and Python (especially task 2). Note that typeglobs do not exist in Raku because the sigil is part of the name stored in a symbol table, while in Perl 5 the name is stored without the sigil.
• Test::More - this core module uses a cute typeglob alias (sub isnt { ... } *isn't = \&isnt) allowing you to write isn't in your tests, as an alternative to isnt
• Dollar Bracket Star ${*...} by snoopyjc (2021)

• Re^7: Introspecting function signatures (Dependency Injection and Monkey Patching)
• STDIN typeglob by Bod (2023)

Updated: Changed title from glob to typeglob in step with xiaoyafeng. Added more examples of typeglobs long after original reply was made.