Documentation for method lookup assembled from the following types:

class Metamodel::ClassHOW

From Metamodel::ClassHOW

(Metamodel::ClassHOW) method lookup

method lookup(Metamodel::ClassHOW:D: $obj, $method-name --> Method:D)

Returns the first matching Method with the provided name. If no method was found, returns a VM-specific sentinel value (typically a low-level NULL value) that can be tested for with a test for definedness. It is potentially faster than .^can but does not provide a full list of all candidates.

say Str.^lookup('Int').perl; # OUTPUT: «method Int (Str:D $: *%_) { #`(Method|39910024) ... }␤» 
 
for <upper-case  uc> {
    Str.^lookup: $^meth andthen .("foo").say
        orelse "method `$meth` not found".say
}
# OUTPUT: 
# method `upper-case` not found 
# FOO

role Metamodel::MethodContainer

From Metamodel::MethodContainer

(Metamodel::MethodContainer) method lookup

method lookup(Metamodel::MethodContainer: $obj, $name --> Method)

Returns the first matching method object of the provided $name or (Mu) if no method object was found. The search for a matching method object is done by following the mro of $obj. Note that lookup is supposed to be used for introspection, if you're after something which can be invoked you probably want to use find_method instead.

say 2.5.^lookup("sqrt").perl:      # OUTPUT: «method sqrt (Rat $: *%_) ...␤» 
say Str.^lookup("BUILD").perl;     # OUTPUT: «submethod BUILD (Str $: :$value = "", *%_ --> Nil) ...␤» 
say Int.^lookup("does-not-exist"); # OUTPUT: «(Mu)␤»

The difference between find_method and lookup are that find_method will use a default candidate for parametric roles, whereas lookup throws an exception in this case, and that find_method honors FALLBACK methods, which lookup does not.