Are f-strings a unique feature to python (3.6 and higher)?

Question

With an f-string you can fill in 'placeholders' in a string directly with some variable value. Opposed to, let's say using the str.format() method, often seen.

Example:

In [1]: x=3
In [2]: y=4
In [3]: print(f'The product of {x} and {y} is {x*y}.')
The product of 3 and 4 is 12.

Is this concept of f-strings only found in python? Or is there any other language that supports this, maybe under a different name?

Answer 1

Short answer: No - not unique to python. In python it was introduced with 3.6 by Literal String Interpolation - PEP 498

In C# there is $ - string interpolation as shorthand for some function you would use String.Format for:

string val = "similar";
string s = $"This is {val}"     // s == "This is similar"

// vs. 

var s2 = string.Format ("This is {0}", val); // {0} = 0th param that follows

Answer 2

You can find it under the name of Template Literals in Javascript as well. In particular, see the section Expression Interpolation for an example similar as the one in OP's question.

Answer 3

The shell: Starting in the Dark Ages shells used to expand parameters in double quoted strings (and unquoted arguments too).

Perl: Perl has a shellish side, and had interpolation in double quoted strings from at least the time I bought the 1st edition of the Camel book and started learning the language.

I think that other people may be more specific on the precise date of introduction of string interpolation in Perl, but I suspect it was there from the beginning.

Many other programming languages, especially those using sigils, share this concept of interpolation.