Bug #86893 for Type-Tiny: Clarify "may" in the docs in relation to using constraint => quote_sub q{...}

Now, Types::Standard does not use Sub::Quote, but for the purposes of this explanation, let's assume that it does. The Object type constraint is a child of Ref, which is a child of Defined, which is a child of Item. The automatic inlining via Sub::Quote will always include the inlining for its parent. Therefore, the Sub::Quote inlining for Object would be something like: !!1 # inline check for Item && defined($_) # inline check for Defined && ref($_) # inline check for Ref && blessed($_) # inline check for Object Most of that is superfluous. Simply checking blessed($_) should be sufficient.

So to answer your questions more specifically, Sub::Quote-provided inlining will be slower if you have deep type constraint hierarchies, because it always checks every ancestor type. Inlining provided by inline_as has the option of not calling the parent type constraint's inlining code, and thus cutting down on the generated checks.