pathlib 和字符串连接的控制顺序

Question

I have a directory I want to save files to, saved as a Path object called dir . I want to autogenerate files names at that path using string concatenation.

The only way I can get this to work in a single line is just through string concatenation:

dir = Path('./Files')
constantString = 'FileName'
changingString = '_001'

path2newfile = dir.as_posix() + '/' + constantString + changingString

print(path2newfile) # ./Files/Filename_001

... which is overly verbose and not platform independent.

What I'd want to do is use pathlib's / operator for easy manipulation of the new file path that is also platform independent. This would require ensuring that the string concatenation happens first, but the only way I know how to do that is to set a (pointless) variable:

filename = constantString + changingString
path2newfile = dir / filename

But I honestly don't see why this should have to take two lines.

If I instead assume use "actual" strings (ie. not variables containing strings), I can do something like this:

path2newfile = dir / 'Filename' '_001'

But this doesn't work with variables.

path2newfile = dir / constantString changingString
# SyntaxError: invalid syntax

So I think the base question is how do I control the order of operators in python? Or at least make the concatenation operator + act before the Path operator / .

Keep in mind this is a MWE. My actual problem is a bit more complicated and has to be repeated several times in the code.

Answer 1

只需在字符串连接周围使用括号：

path2newfile = dir / (constantString + changingString)

Answer 2

Have you considered using Python f-strings?

It seems like your real-world example has a "template-y" feel to it, so something like:

path / f"constant part {variable_part}"

may work.

Answer 3

Use os.path.join() .
It's both platform-independent and you can plug the desired path parts as arguments.