Add Grab All The Method Names Defined In A Ruby File as a sed til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_1089 TILs and counting..._
+_1090 TILs and counting..._
 
 ---
 
@@ -943,6 +943,7 @@ _1089 TILs and counting..._
 
 - [Apply Multiple Substitutions To The Input](sed/apply-multiple-substitutions-to-the-input.md)
 - [Extract Value From Command Output With Sed](sed/extract-value-from-command-output-with-sed.md)
+- [Grab All The Method Names Defined In A Ruby File](sed/grab-all-the-method-names-defined-in-a-ruby-file.md)
 - [Output Only Lines Involved In A Substitution](sed/output-only-lines-involved-in-a-substitution.md)
 - [Use An Alternative Delimiter In A Substitution](sed/use-an-alternative-delimiter-in-a-substitution.md)
 

sed/grab-all-the-method-names-defined-in-a-ruby-file.md

@@ -0,0 +1,27 @@
+# Grab All The Method Names Defined In A Ruby File
+
+I wanted a listing of all the methods defined in a Ruby file. Metaprogramming
+aside, I figured I could write a one-line `sed` script to effectively do this.
+
+```bash
+$ sed -n 's/[[:space:]]*def \([[:alnum:]_?!]*\).*/\1/p' file.rb
+```
+
+Let's break this down.
+
+- `[[:space:]]*` accounts for any level of indentation.
+- `def ` matches againts the start of a method definition.
+- `\(...\)` is a capture that can be referenced in the replace side of the
+  script.
+- `[[:alnum:]_?!]*` represents the characters that can make up a Ruby method
+  name, this is equivalent to writing `[a-zA-Z0-9_?!]*`.
+- `.*` is the final part of the regex match which ensures the rest of the line
+  is loaded into the pattern space so that the replacement will only be the
+  method name.
+- `\1` replaces everything in the first part of the script with the capture
+  which is just the method name.
+- combining the `-n` and `p` flags ensures that only lines with substitutions
+  are printed.
+
+This probably isn't perfect, but it is good enough to reference from time to
+time in my shell history.