Hi Timo, Thanks for the answer:
> the liskov substitution principle I didn't knew about this principle. I'm now going down the rabbit hole. Is this always the case for all the derived classes in Raku? Best regards, David Santiago Timo Paulssen <t...@wakelift.de> escreveu no dia terça, 11/02/2020 à(s) 13:32: > > On 11/02/2020 14:14, David Santiago wrote: > > Awesome explanation! Thank you! > > > > BTW, > >> my Blob $read = Buf.new; > > Is it creating either a Blob or a Buf? > > > > Regards, > > David Santiago > > > Hi David, > > "my Blob $read" will define the variable $read to 1) only accept things > that typecheck against Blob, and 2) has the starting value of Blob (the > Blob type object). Assigning Buf.new to it will assign the newly created > Buf object to the variable, because a Buf Is-A Blob (by the liskov > substitution principle, everywhere you can use a Blob, you can also use > a Buf, but not the other way around). > > BTW, assigning to a variable with a % or @ sigil behaves differently. > That is called "list assignment" and will actually use whatever type the > % or @ variable is defined to use (Hash and Array by default) and store > the values from the right-hand side of the assignment into the existing > object. This is why "my %foo = SetHash.new(<a b c>)" will result in a > Hash. For this example, you would want "my %foo is SetHash = <a b c>" > instead. > > Hope that clears things up > - Timo >
