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less than awesome error message, undocumented "feature"

From:
John Macdonald
Date:
August 21, 2014 18:44
Subject:
less than awesome error message, undocumented "feature"
Message ID:
01EF6156B387B14E8278ECC376793BE18F52A8CA@EXMB5.ad.oicr.on.ca
The error exception:

    Role 'XXX|YYY|ZZZ' has encountered a class attribute conflict during composition.  This is a fatal error and cannot be disambiguated.

is not very helpful.  Which attribute had the conflict?  Which two of XXX, YYY, and ZZZ did the conflict come from?  (I suspect that it must be merging ZZZ into the previously merged XXX|YYY when it generates this exception, so ZZZ is one of the contributors to the conflict.  I'd also change the second sentence to "Role composition can never automatically determine a safe way to disambiguate conflicts - the calling code must handle this explicitly."  (That is more explicit about the need for the calling code to handle disambiguation in all cases [the original  can be read to imply that automatic disambiguation might be possible for some other cases), while removing the rather obvious "thias is a fatal error" in the text of a thrown exception.)

This comes from:

    MooseX::ClassAttribute::Trait::Role::Composite::_merge_class_attributes



John Macdonald
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