python - Python 3.x 中新的 print 函数相对于 Python 2 的 print 语句有什么优势？

Question

我多次听说 print 作为函数 (3.x) 比作为语句 (2.x) 要好。但为什么呢？

我喜欢它是一个声明，主要是因为它允许我少输入两个字符(即括号)。

我很想看看 print 语句只是没有削减它的一些情况，并且功能更优越。

Answer 1

Rationale

The print statement has long appeared on lists of dubious language features that are to be removed in Python 3000, such as Guido's "Python Regrets" presentation [1]. As such, the objective of this PEP is not new, though it might become much disputed among Python developers.

The following arguments for a print() function are distilled from a python-3000 message by Guido himself [2]:

• print is the only application-level functionality that has a statement dedicated to it. Within Python's world, syntax is generally used as a last resort, when something can't be done without help from the compiler. Print doesn't qualify for such an exception.
• At some point in application development one quite often feels the need to replace print output by something more sophisticated, like logging calls or calls into some other I/O library. With a print() function, this is a straightforward string replacement, today it is a mess adding all those parentheses and possibly converting >>stream style syntax.
• Having special syntax for print puts up a much larger barrier for evolution, e.g. a hypothetical new printf() function is not too far fetched when it will coexist with a print() function.
• There's no easy way to convert print statements into another call if one needs a different separator, not spaces, or none at all. Also, there's no easy way at all to conveniently print objects with some other separator than a space.
• If print() is a function, it would be much easier to replace it within one module (just def print(*args):...) or even throughout a program (e.g. by putting a different function in __builtin__.print). As it is, one can do this by writing a class with a write() method and assigning that to sys.stdout – that's not bad, but definitely a much larger conceptual leap, and it works at a different level than print.

— PEP 3105 – Make print a function