[Libguestfs] IRC question about ?foo etc

Richard W.M. Jones rjones at redhat.com
Sun Jan 8 23:21:48 UTC 2017


On Sun, Jan 08, 2017 at 11:13:42PM +0000, Richard W.M. Jones wrote:
>   let other_func ~foo ~bar ?baz =
>     func ~foo ~bar ?baz

Actually there is a third issue which is what makes this even
more confusing.

?baz (when calling a function) expects that baz (the binding) is an
option, and passes either nothing (if baz = None) or the optional
argument (if baz <> None).  In effect it means pass baz directly to
the function, since the function implementation is expecting an option
type for this parameter.

Rich.

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