The problem of "print line if line = DATA.gets"
Right now, I find the following code will raise an exception:
print line if line = DATA.gets
undefined local variable or method `line' for main:Object (NameError)¶
"print line while line = DATA.gets" also doesn't work, maybe "unless" "until" modifiers either.
It seems that the Ruby interpreter is too impatient, once seeing unassigned variable "line", it croaks.
However, the expression after "if" or "while" modifier should be evaluated first. Logically, I think the code above should work properly, there's no need to write "line = nil" before it.