Common Lisp格式实际上什么时候打印？ [英] When does format actually print in Common Lisp?

问题描述

 （defun micro-read-eval-print（）
 （格式tMicro>）
（let（（form（read-line））））
  

当我运行它时，我得到以下内容：

  CL-USER> （micro-read-eval-print）
（m-quote a）
 Micro>请注意，我输入（m-quote a），而Lisp解释器输出$ m $ a $ Micro> NIL。
 
现在，我预计这些事件会以相反的顺序发生。自从格式化语句首先打印出来之后，我预料会先打印出Micro>。为什么不先打印？我该怎么做，以确保它是首先打印？
解决方案
尝试添加
 （defun micro-read-eval-print（）
（format tMicro>）
（finish-output）
（let（（form（read-line）））））
  
我相信你遇到标准io（stdio）的缓冲，在C语言中，这个语言通常被 fflush（）绕过。
 
 
 
  finish-output 看起来就是C标准库的Common Lisp相当于 fflush 。
 
I have the following Common Lisp code:
(defun micro-read-eval-print ()
    (format t "Micro > ")
    (let ((form (read-line)))))
When I run it, I get the following:
CL-USER> (micro-read-eval-print)
(m-quote a)
Micro > NIL
Note that I typed in "(m-quote a)", while the Lisp interpreter output "Micro > NIL".

Now, I would have expected these events to happen in the reverse order.  I would have expected "Micro > " to have been printed first since the format statement comes first.  Why isn't it printed first?  And what do I have to do to make sure it is printed first?
解决方案
Try adding
(defun micro-read-eval-print ()
    (format t "Micro > ")
    (finish-output)
    (let ((form (read-line)))))
I believe you are encountering the buffering of standard io (stdio) which, in C, is commonly bypassed via fflush() in that language.

finish-output appears to be the Common Lisp equivalent of C standard library's fflush.

                        
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