问题
Consider the following string building statement:
s="svn cp %s/%s/ %s/%s/" % (root_dir, trunk, root_dir, tag)
Using four %s can be confusing, so I prefer using variable names:
s="svn cp {root_dir}/{trunk}/ {root_dir}/{tag}/".format(**SOME_DICTIONARY)
When root_dir, tag and trunk are defined within the scope of a class, using self.__dict__ works well:
s="svn cp {root_dir}/{trunk}/ {root_dir}/{tag}/".format(**self.__dict__)
But when the variables are local, they are not defined in a dictionary, so I use string concatenation instead:
s="svn cp "+root_dir+"/"+trunk+"/ "+root_dir+"/"+tag+"/"
I find this method quite confusing, but I don't know any way to construct a string using in-line local variables.
How can I construct the string using variable names when the variables are local?
Update: Using the locals() function did the trick.
Note that mixing local and object variables is allowed! e.g.,
s="svn cp {self.root_dir}/{trunk}/ {self.root_dir}/{tag}/".format(**locals())
回答1:
You can use locals() function
s="svn cp {root_dir}/{trunk}/{root_dir}/{tag}/".format(**locals())
EDIT:
Since python 3.6 you can use string interpolation:
s = f"svn cp {root_dir}/{trunk}/{root_dir}/{tag}/"
回答2:
Have you tried s="svn cp {root_dir}/{trunk}/ {root_dir}/{tag}/".format(**locals()) ?
回答3:
less cryptic and faster
"my name is {__name__}".format_map(locals())
str.format_map(mapping)
Similar to str.format(**mapping), except that mapping is used directly and not copied to a dict.
来源：https://stackoverflow.com/questions/17471439/python-formatting-a-string-using-variable-names-placeholders