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stanlick (307) [Avatar] Offline
#1
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
#2
Thanks a lot for your kind words, man smilie

Yours
Dierk