The Author Online Book Forums are Moving

The Author Online Book Forums will soon redirect to Manning's liveBook and liveVideo. All book forum content will migrate to liveBook's discussion forum and all video forum content will migrate to liveVideo. Log in to liveBook or liveVideo with your Manning credentials to join the discussion!

Thank you for your engagement in the AoF over the years! We look forward to offering you a more enhanced forum experience.

stanlick (307) [Avatar] Offline
Hey Dierk --

I'll be taking on nearly a year of teaching Grrovy/Grails and can see you are the man! I'm churning through the MEAP and you have a nice writing style. I have written for Manning, and realize the labor involved. While I'm not too deep into the material and actually learning it myself, I am still interested in helping out. As will likely be the case for most readers, page 70 will be point where the reader will s l o w d o w n. I see you actually asking for thoughts about this, so I'll propose a bit.

def greeting = readFromConsole()

When I read this, I am once again thinking about Java Generics and those damn wildcard types. After standing on my head and reading everything I could get my hands on (and private conversations with Brian Goetz) I finally got it. I went on to write a training course and have pulled a bit from it below.

"The thing about the wildcards that hoses everyone is that List<? super Android> does *not* mean "List of things that are Android or its supertypes." It means "List of things of some type Z, where Z must be Android or supertype, but I don't know exactly what Z is." So yes, CellPhone is not considered explicitly; instead, List<? super Android> means that all we know about it is that it is safe to put Androids into it (see the get/put principle here.)" <br /> <br /> Do you suppose it would be clearer (or muddier) to describe the type greeting in these terms? <br /> <br /> P.S. Thanks for investing so much of your time in this project brother. <br /> <br /> Peace, <br /> Scott Stanlick
Mittie (397) [Avatar] Offline
Thanks a lot for your kind words, man smilie