I do hope the points Anon raised are among "topics for meditation", since much of the talk is about constant folding at the compile time. Anyhow, there's little to fault in his overall assessment.

Consider the enumerated constant in C:

  enum { FOO = 2 };
  enum { FOO = 3 }; // error: redefinition of enumerator
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Contrast this with Perl:

  *FOO = \1.2;
  *FOO = \3.4;
  print our $FOO;   # prints 3.4
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Perl has no means to protect an identifier in a given scope. This is useful for example in guarding against file level symbol clashes. (Perl isn't C, of course, but some perl modules do export lots of symbols: Fcntl, POSIX, ....)

Another sign of the problem is that constants are commonly used via hashes to keep things tidy and structured. A particular case would be the use Config. If you have conditional code-paths that depend on, say, $Config{longsize}, then these tests are not folded during compilation even though %Config::Config is supposedly read-only.

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