[python] Is there a Python equivalent to Ruby's string interpolation?

Ruby example:

name = "Spongebob Squarepants"
puts "Who lives in a Pineapple under the sea? \n#{name}."

The successful Python string concatenation is seemingly verbose to me.

import inspect
def s(template, **kwargs):
    "Usage: s(string, **locals())"
    if not kwargs:
        frame = inspect.currentframe()
        try:
            kwargs = frame.f_back.f_locals
        finally:
            del frame
        if not kwargs:
            kwargs = globals()
    return template.format(**kwargs)

Usage:

a = 123
s('{a}', locals()) # print '123'
s('{a}') # it is equal to the above statement: print '123'
s('{b}') # raise an KeyError: b variable not found

PS: performance may be a problem. This is useful for local scripts, not for production logs.

Duplicated:

• Python string formatting: % vs. .format

• What is the Python equivalent of embedding an expression in a string? (ie. "#{expr}" in Ruby)

• What is Ruby equivalent of Python's `s= "hello, %s. Where is %s?" % ("John","Mary")`

• Is there a Python equivalent to Ruby's string interpolation?

Python's string interpolation is similar to C's printf()

If you try:

name = "SpongeBob Squarepants"
print "Who lives in a Pineapple under the sea? %s" % name

The tag %s will be replaced with the name variable. You should take a look to the print function tags: http://docs.python.org/library/functions.html

I've developed the interpy package, that enables string interpolation in Python.

Just install it via pip install interpy. And then, add the line # coding: interpy at the beginning of your files!

Example:

#!/usr/bin/env python
# coding: interpy

name = "Spongebob Squarepants"
print "Who lives in a Pineapple under the sea? \n#{name}."

Since Python 2.6.X you might want to use:

"my {0} string: {1}".format("cool", "Hello there!")

For old Python (tested on 2.4) the top solution points the way. You can do this:

import string

def try_interp():
    d = 1
    f = 1.1
    s = "s"
    print string.Template("d: $d f: $f s: $s").substitute(**locals())

try_interp()

And you get

d: 1 f: 1.1 s: s

You can also have this

name = "Spongebob Squarepants"
print "Who lives in a Pineapple under the sea? \n{name}.".format(name=name)

http://docs.python.org/2/library/string.html#formatstrings

String interpolation is going to be included with Python 3.6 as specified in PEP 498. You will be able to do this:

name = 'Spongebob Squarepants'
print(f'Who lives in a Pineapple under the sea? \n{name}')

Note that I hate Spongebob, so writing this was slightly painful. :)

Python 3.6 and newer have literal string interpolation using f-strings:

name='world'
print(f"Hello {name}!")