ruby - 分配 begin-end-while block 的结果会阻止执行该 block

Question

您可以将 block 的结果分配给变量:

a = begin
  1
end
a #=> 1

与此同时，while 可以像这样附加在 block 之后:

begin
  puts "this will be printed once"
end while false

并且它至少会被执行一次。如果您为该 being-end-while block 分配一个变量，它就不会再执行:

a = begin
  puts "this won't be printed at all"
end while false

谁能给我解释一下这是怎么回事？

Answer 1

如果加上赋值，则解释为:

(a = begin
  puts "this won't be printed at all"
end) while false

如何在 begin ... end while false 两边加上括号？

a = (begin
  puts "this won't be printed at all"
end while false)
# prints: this won't be printed at all
# a => nil