ruby有一些边缘情况很难解释,因为解析会带来一些有趣的问题.我在这里列出其中两个.如果你知道更多,那么添加到列表中.
def foo 5 end # this one works if (tmp = foo) puts tmp.to_s end # However if you attempt to squeeze the above # three lines into one line then code will fail # take a look at this one. I am naming tmp2 to # avoid any side effect # Error: undefined local variable or method ‘tmp2’ for main:Object puts tmp2.to_s if (tmp2 = foo)
这是另一个.
def x 4 end def y x = 1 if false x + 2 end # Error: undefined method `+' for nil:NilClass puts y
但是,如果您注释掉x = 1行,如果为false,则代码将正常工作.