Posted on 2008-01-27 15:53
dennis 阅读(361)
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动态语言
class BitStruct
def self.list(name,element)
module_eval <<-HERE
rest :body
def #{name.to_s}=(elist)
e=Object.const_get(:#{element})
if elist.respond_to? :each and elist.respond_to? :[] and elist[0].is_a? e
elist.each{ |value| self.body+=value}
elsif elist.is_a? e
self.body=elist
else
raise ArgumentError,elist.to_s<<" is not a #{element}",caller
end
end
def #{name.to_s}
result=[]
e=Object.const_get(:#{element})
size=e.new.size
num=self.body.size/size-1
for i in 0..num
result[i]=e.new(self.body[i*size,size])
end
result
end
HERE
end
end
利用Ruby的动态特性，很容易就达到了，使用的话：
class A <BitStruct
unsigned :id,32
end
class B<BitStruct
list :aList,A
end
alist=[]
for i in 0..10
a=A.new
a.id=i
alist.unshift a
end
b=B.new
b.aList=alist
b.aList.each{|e| puts e.id}