␡
- 2.1 Representing Ordinary Strings
- 2.2 Representing Strings with Alternate Notations
- 2.3 Using Here-Documents
- 2.4 Finding the Length of a String
- 2.5 Processing a Line at a Time
- 2.6 Processing a Character or Byte at a Time
- 2.7 Performing Specialized String Comparisons
- 2.8 Tokenizing a String
- 2.9 Formatting a String
- 2.10 Using Strings as IO Objects
- 2.11 Controlling Uppercase and Lowercase
- 2.12 Accessing and Assigning Substrings
- 2.13 Substituting in Strings
- 2.14 Searching a String
- 2.15 Converting Between Characters and ASCII Codes
- 2.16 Implicit and Explicit Conversion
- 2.17 Appending an Item onto a String
- 2.18 Removing Trailing Newlines and Other Characters
- 2.19 Trimming Whitespace from a String
- 2.20 Repeating Strings
- 2.21 Embedding Expressions within Strings
- 2.22 Delayed Interpolation of Strings
- 2.23 Parsing Comma-Separated Data
- 2.24 Converting Strings to Numbers (Decimal and Otherwise)
- 2.25 Encoding and Decoding <tt>rot13</tt> Text
- 2.26 Encrypting Strings
- 2.27 Compressing Strings
- 2.28 Counting Characters in Strings
- 2.29 Reversing a String
- 2.30 Removing Duplicate Characters
- 2.31 Removing Specific Characters
- 2.32 Printing Special Characters
- 2.33 Generating Successive Strings
- 2.34 Calculating a 32-Bit CRC
- 2.35 Calculating the SHA-256 Hash of a String
- 2.36 Calculating the Levenshtein Distance Between Two Strings
- 2.37 Encoding and Decoding Base64 Strings
- 2.38 Expanding and Compressing Tab Characters
- 2.39 Wrapping Lines of Text
- 2.40 Conclusion
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
2.22 Delayed Interpolation of Strings
Sometimes we might want to delay the interpolation of values into a string. There is no perfect way to do this.
A naive approach is to store a single-quoted string and then evaluate it:
str = '#{name} is my name, and #{nation} is my nation.'
name, nation = "Stephen Dedalus", "Ireland"
s1 = eval('"' + str + '"')
# Stephen Dedalus is my name, and Ireland is my nation.
However, using eval is almost always the worst option. Any time you use eval, you are opening yourself up to many problems, including extremely slow execution and unexpected security vulnerabilities, so it should be avoided if at all possible.
A much less dangerous way is to use a block:
str = proc do |name, nation|
"#{name} is my name, and #{nation} is my nation."
end
s2 = str.call("Gulliver Foyle", "Terra")
# Gulliver Foyle is my name, and Terra is my nation.