Someone has recently demonstrated to me that we can print variables in Python like how Perl does.
Instead of:
print("%s, %s, %s" % (foo, bar, baz))
we could do:
print("%(foo)s, %(bar)s, %(baz)s" % locals())
Is there a less hacky looking way of printing variables in Python like we do in Perl? I think the 2nd solution actually looks really good and makes code a lot more readable, but the locals() hanging around there makes it look like such a convoluted way of doing it.
The only other way would be to use the Python 2.6+/3.x .format() method for string formatting:
# dict must be passed by reference to .format()
print("{foo}, {bar}, {baz}").format(**locals())
Or referencing specific variables by name:
# Python 2.6
print("{0}, {1}, {2}").format(foo, bar, baz)
# Python 2.7/3.1+
print("{}, {}, {}").format(foo, bar, baz)
vars() instead of locals(). Also vars(obj) to use obj.__dict__ for the substitutionsUsing % locals() or .format(**locals()) is not always a good idea. As example, it could be a possible security risk if the string is pulled from a localization database or could contain user input, and it mixes program logic and translation, as you will have to take care of the strings used in the program.
A good workaround is to limit the strings available. As example, I have a program that keeps some informations about a file. All data entities have a dictionary like this one:
myfile.info = {'name': "My Verbose File Name",
'source': "My Verbose File Source" }
Then, when the files are processes, I can do something like this:
for current_file in files:
print 'Processing "{name}" (from: {source}) ...'.format(**currentfile.info)
# ...
Explicit is better than implicit. in exactly this context.I prefer the .format() method myself, but you can always do:
age = 99
name = "bobby"
print name, "is", age, "years old"
Produces: bobby is 99 years old. Notice the implicit spaces.
Or, you can get real nasty:
def p(*args):
print "".join(str(x) for x in args))
p(name, " is ", age, " years old")
Since Python 3.6, you could have what you wanted.
>>> name = "world"
>>> print(f'hello {name}')
hello world
note the string prefix f above
The answer is, no, the syntax for strings in Python does not include variable substitution inthe style of Perl (or Ruby, for that matter). Using … % locals() is about as slick as you are going to get.
