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

Python 3.6 will add literal string interpolation similar to Ruby's string interpolation. Starting with that version of Python (which is scheduled to be released by the end of 2016), you will be able to include expressions in "f-strings", e.g.

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

Prior to 3.6, the closest you can get to this is

name = "Spongebob Squarepants"
print("Who lives in a Pineapple under the sea? %(name)s." % locals())

The % operator can be used for string interpolation in Python. The first operand is the string to be interpolated, the second can have different types including a "mapping", mapping field names to the values to be interpolated. Here I used the dictionary of local variables locals() to map the field name name to its value as a local variable.

The same code using the .format() method of recent Python versions would look like this:

name = "Spongebob Squarepants"
print("Who lives in a Pineapple under the sea? {name!s}.".format(**locals()))

There is also the string.Template class:

tmpl = string.Template("Who lives in a Pineapple under the sea? $name.")
print(tmpl.substitute(name="Spongebob Squarepants"))

Since Python 2.6.X you might want to use:

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

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}."

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