What's the difference between $?CLASS and ::?CLASS

Question

The Raku docs describe ::?CLASS as a compile-time variable that answers "Which class am I in?". Then, a couple of paragraphs later, it mentions $?CLASS, and says that it answers "Which class am I in? (as variable)".

What's the difference between these two variables? They often seem to contain the same value – do they always? Or are there differences I haven't observed?

Try doing `class A { method foo($?CLASS:D:) { } }` :-) – Elizabeth Mattijsen Feb 23 '22 at 19:16 — Elizabeth Mattijsen, Feb 23 '22 at 19:16

raiph · Accepted Answer · 2022-02-23T20:43:37.680

8

These two forms of compile-time variables are different syntactically.

The syntactic form ::?foo may be used as, and will be evaluated as:

A term (just like a variable such as $?foo).
A type constraint (unlike a variable such as $?foo).

edited Feb 23 '22 at 20:43

answered Feb 23 '22 at 20:30

raiph

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What's the difference between $?CLASS and ::?CLASS

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