# ElTypeRef implementation eval_type from ElExpression missing

**Category:** [BMM/Expressions](https://discourse.openehr.org/c/bmm-el/60)
**Created:** 2020-06-09 12:59 UTC
**Views:** 591
**Replies:** 5
**URL:** https://discourse.openehr.org/t/eltyperef-implementation-eval-type-from-elexpression-missing/761

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## Post #1 by @Bert_Verhees

ElTypeRef is in that inheritance-line the last class and not an abstract class.
Same for ElConstraintExpression, ElUnaryOperator and ElBinaryOperator

My editor complains not having done this.

;-)

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## Post #2 by @thomas.beale

Good catch - fixed now.

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## Post #3 by @Bert_Verhees

You should also add effective_type() to BmmContainerType for about the same reasons

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## Post #4 by @thomas.beale

Again right; the change is now up.

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## Post #5 by @Bert_Verhees

Keep the good thing rolling, found another one ;-)

flattenedTypeList() must be implemented in BmmTupleType and BmmSignature

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## Post #6 by @thomas.beale

Also fixed :)

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**Canonical:** https://discourse.openehr.org/t/eltyperef-implementation-eval-type-from-elexpression-missing/761
**Original content:** https://discourse.openehr.org/t/eltyperef-implementation-eval-type-from-elexpression-missing/761