CODEWITHSUNDEEP
raku
Christopher Bottoms
Christopher Bottoms

Reputation: 11168

Are constants in module files supposed to be imported automatically?

Given the module file test.pm6:

constant $AUTHOR='me';

And the script test_script.p6:

use lib '.';

use test;

my $AUTHOR = 'someone';

I get the following warning when I compile check test_script.p6:

perl6 -c test_script.p6
Potential difficulties:
    Redeclaration of symbol '$AUTHOR'
    at test_script.p6:5
    ------> my $AUTHOR⏏ = 'someone';
Syntax OK

However, simply changing test.pm6 to one of the following makes this warning go away:

my $AUTHOR='me';

or

my constant $AUTHOR='me';

So, the question is whether constants should be imported automatically or is this a bug?

This is using Rakudo Star 2017.01 Release Candidate 0 installed on CentOS Linux release 7.3.1611 (Core).

Upvotes: 9

Views: 212

Answers (1)

user2410502
user2410502

Reputation:

This is not a bug. Constants are our scoped by default and your constant in test.pm6 is still in the mainline and so gets placed into the GLOBAL namespace and since it's an our, it's visible in your main script.

One way to avoid it is what you found: to use a my on constants/classes (as they default to our). Or conversely, to use an our on subroutines/variables that you want to make visible (as subs default to my).

Another way is to use, say, unit module BlahBlah; at the top of your module file, and then these symbols will be in BlahBlah namespace and not in the GLOBAL and so will not be visible in the main script directly (our symbols can still be accessed as BlahBlah::whatever)

P.S.: those on 2016 Rakudos won't observe this behaviour due to lexical module loading bug, which got fixed only in 2017.01 compiler release (and was merged to master a couple of days after 2016.12 compiler release)

Upvotes: 12

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