Ruby - String String Heredocs
Introduction
In Ruby you can create long strings spanning multiple lines between single or double quotes.
Many Ruby programmers prefer to use a string called a heredoc.
A heredoc is a block of text that starts by specifying an end marker, which is simply an identifier of your choice.
Here, I specify EODOC as the end marker:
hdoc1 = <<EODOC
<<EODOC tells Ruby that everything following the previous line is a single string that terminates when the end marker is located.
The string is assigned to the variable, hdoc1.
Here is an example of a complete heredoc assignment:
Demo
hdoc1 = <<EODOC this is a tes #{"test".upcase}, test # from ww w .ja va2 s . com this is a test EODOC puts hdoc1
Result
By default, heredocs are treated as double-quoted strings, so expressions such as #{"test".upcase} will be evaluated.
If you want a heredoc to be treated as single-quoted string, specify its end marker between single quotes:
Demo
hdoc2 = <<'EODOC' this is a tes #{"test".upcase}, test # ww w . j a va 2 s.c om this is a test EODOC puts hdoc2
Result
The end marker of a heredoc must, by default, be placed flush with the left margin.
If you want to indent it, you should use <<- rather than << when assigning the end marker:
Demo
hdoc3 = <<-EODOC this is a tes #{"test".upcase}, test # ww w .j a va 2 s. co m this is a test EODOC puts hdoc3
Result
It is up to you to pick an appropriate end marker.
It is even legitimate to use a reserved word:
Demo
hdoc4 = <<def this is a tes #{"test".upcase}, test # from w ww.ja v a2 s . c om this is a test def puts hdoc4 A variable to which a heredoc is assigned can be used just like any other string variable: puts( hdoc1 )
Result
