Porting from Serilog.Filters.Expressions : Missing Has() function

[warrenbuckley]

When porting over from Serilog.Filters.Expressions it's missing the function Has() to check for an existence of a property on the log.
Is there any plan to add this back in @nblumhardt ?

Examples are

Has(@x)
Has(Duration) and Duration > 1000

[nblumhardt]

Hi @warrenbuckley!

I missed mention of this elsewhere --- the function has been renamed to IsDefined() (since it works with any expression, not just top-level properties):

IsDefined(@x)
IsDefined(Duration) and Duration > 1000

(Although that second example is identical to Duration > 1000.)

Guessing that you have found NameResolver, which provides a way to hook new functions/aliases in. Let me know if you need more help with it.

[warrenbuckley]

I have added a PR for you to consider @nblumhardt
#65