在Android中的GridLayout中重新排序项目的动画(Animating of reordering items in GridLayout in Android)

 print不是原子的。 
 
 以下行： 
 
        print "%s :: %s" % (self.num, text)
 
 被翻译成以下字节码： 
 
         24 LOAD_CONST               1 ('%s :: %s')
         27 LOAD_FAST                0 (self)
         30 LOAD_ATTR                3 (num)
         33 LOAD_FAST                1 (text)
         36 BUILD_TUPLE              2
         39 BINARY_MODULO       
         40 PRINT_ITEM          
         41 PRINT_NEWLINE       
 
 如您所见，那里有两个打印字节码（ PRINT_ITEM和PRINT_NEWLINE ）。 如果线程在两者之间被抢占，你会看到你所看到的。 
 
 我同意其他人的观点， sys.stdout.write()对于这个用例来说是一个更安全的赌注，因为： 
 
 
 
 它会强制你在编写之前格式化整个字符串（使用print可能会意外地使用print a, b, c,最后print a, b, c,三个单独的写入而不是一个）; 
 
 
 它回避了软空间和自动换行的问题，两者都可以与程序其他部分的print语句进行交互。 
 

print is not atomic.
 
The following line:
 
        print "%s :: %s" % (self.num, text)
 
get translated into the following bytecodes:
 
         24 LOAD_CONST               1 ('%s :: %s')
         27 LOAD_FAST                0 (self)
         30 LOAD_ATTR                3 (num)
         33 LOAD_FAST                1 (text)
         36 BUILD_TUPLE              2
         39 BINARY_MODULO       
         40 PRINT_ITEM          
         41 PRINT_NEWLINE       
 
As you can see, there are two printing bytecodes there (PRINT_ITEM and PRINT_NEWLINE). If the thread gets preempted between the two, you would see what you are seeing.
 
I agree with others that sys.stdout.write() is a safer bet for this use case since:
 
 
 
it forces you to format the entire string before you write it (with print you can accidentally use print a, b, c, and end up with three separate writes instead of one);
 
 
it sidesteps the issues of softspace and automatic newline, both of which can interact with print statements in other parts of the program.