Ruby - 重新定义实例方法不起作用
我重新定义实例方法的简单尝试不起作用
class File
alias_method :old_atime, :atime
def atime(*args)
puts "helllllo"
old_atime(*args)
end
end
f = File.new("C:\\abc.txt","w")
puts f.atime
知道为什么吗？
我试图在每次调用 File#atime 时打印“helllllo”。甚至 alias old_atime atime 也不起作用。
我在这里做错了什么吗？
My simple attempt to redefine instance methods are not working
class File
alias_method :old_atime, :atime
def atime(*args)
puts "helllllo"
old_atime(*args)
end
end
f = File.new("C:\\abc.txt","w")
puts f.atime
Any idea why?
I'm attempting to print "helllllo" everytime File#atime is called. Even alias old_atime atime is not working.
Is there something I'm doing wrong here?
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评论（3）
上面的代码可以完美地工作。 Puts “helllllo” 将“helllllo”写入您打开的文件中。放入用于写入的文件实例中。
只需调用 f.close 并在文本编辑器中打开文件。就可以看到内容了。
Above code works perfectly as it should be. Puts "helllllo" writes "helllllo" in to your opened file. Puts inside the file instance meant for writing.
Just call f.close and open your file in text editor. You can see the content.
是的，拉梅什是对的。试试这个：
问题是“puts”在 File 中定义用于写入文件。您需要使用除非在更具体的范围中定义的内核。
Yep, Ramesh is right. Try this:
The issue is that 'puts' is defined in File for writing to files. You want the Kernel one which is used unless defined in a more specific scope.
这应该可以正常工作，但是
IO#puts写入IO对象本身，而不 STDOUT。换句话说，它正在写入文件。调用
f.atime几次，然后在irb中调用f.close，您应该会看到它打印helllllo到每次调用atime的文件。要打印到 STDOUT，您可以使用
$stdout.puts或Kernel.puts。This should work fine, but
IO#putswrites to theIOobject itself, not STDOUT. In other words, it's writing to the file.Call
f.atimea few times and thenf.closewithinirband you should see it printinghellllloto the file for each call toatime.To print to STDOUT, you could use
$stdout.putsorKernel.puts.