I'm messing around with Ruby and I'm trying to understand how the #{} operation works.
b = "puts \'Hello World\'"
r = "Testing .... #{b}"
When running this code, nothing its printed to the screen.
However this does print to the screen
b = "puts \'Hello World\'"
r = "Testing .... #{puts 'Hello World'}"
Why does the 2nd example print to the screen and the first doesn't.
Thanks
String interpolation (the #{} operation) evaluates everything between those braces as code and converts the returned value from execution to a string and places that string in the place of the #{}.
In the first example the string r includes b, and b is just the string "puts \'Hello World\'". In this case, "puts" has no special meaning because it is just a string. So in this first case, r becomes:
"Testing .... #{"puts \'Hello World\'"}"
which then becomes:
"Testing .... puts \'Hello World\'"
In the second example you are including the final value from executing puts 'Hello World' within the string r. Since puts returns nil, r becomes
"Testing .... #{nil}"
which then becomes:
"Testing .... "
r to be the string "Testing .... puts \'Hello World\'", and you want that to be printed, you can just do puts r. Can you explain a bit more about what you want to have happen?
b = -> { puts 'hello' } and call that from within the string: r = "Testing #{b.call}"
"puts 'Hello World'"vs.puts 'Hello World'. Sure, both programs containputs, but in one of them it’s code and in the other it’s just part of a string literal.