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Allow invisible logical return values #135
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Yeah, it's too much of a hack.
What's the problem with an invisibly return +
valueClass = "logical"?@hadley: This:
> dbDisconnect standardGeneric for "dbDisconnect" defined from package "DBI" defined with value class: "logical" function (conn, ...) { ans <- standardGeneric("dbDisconnect") .valueClassTest(ans, "logical", "dbDisconnect") } <environment: 0x56ef4c8> Methods may be defined for arguments: conn Use showMethods("dbDisconnect") for currently available ones.The
.valueClassTest()call always returns a visible value. The only way I see around this is to omitvalueClass(in this case there's no.valueClassTest()call), I guess I'm going to do that.Oh got it.
I think it's reasonable to omit the
valueClasssince the tests similarly enforce the API.- added a commit that references this issue
on Dec 2, 2016 - locked and limited conversation to collaborators
on Oct 8, 2020
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All generics that return a logical should raise an error in case of failure (#51), and return TRUE otherwise (for compatibility). Because the return value is practically useless (at least in interactive mode), it should be invisible, but this is possible only if
valueClass = "logical"is not defined for these generics.It looks like lifting this requirement doesn't have an effect on existing backends.