Extract Method
Extract Method moves a block of statements into a function of its own, called where the block was. Here seven ifs inside each other are too deep to follow, so EK9 refuses it - E11011, explained in the Hovers panel; moving the inner four into a function of their own brings both under the limit. To play it in the IDE: Help > Lessons > Refactoring…, or ek9 -ide -lesson extract-method.
Start from
The code the lesson starts from: copy it into a file of your own and follow the steps.
Fails with E11011: excessive nesting - extract function
#!ek9 defines module error.e11011.bad defines constant LEVEL_TWO <- 2 LEVEL_THREE <- 3 LEVEL_FOUR <- 4 LEVEL_FIVE <- 5 LEVEL_SIX <- 6 defines function deepSimpleNesting() -> mainValue as Integer stdout <- Stdout() if mainValue > 0 if mainValue > 1 if mainValue > LEVEL_TWO if mainValue > LEVEL_THREE if mainValue > LEVEL_FOUR if mainValue > LEVEL_FIVE if mainValue > LEVEL_SIX stdout.println(`${mainValue} is above every level`)
Step 1: The statements
Select from if mainValue > LEVEL_THREE, on line 19, to the end of the line with stdout.println, line 23.
Step 2: Extract Method
Choose Refactor > Extract Method…
Name it reportHighLevels - what the block does - and choose Preview.
Step 3: Preview and apply
The preview shows every change the refactoring makes; then the IDE formats each file it changed. Choose Apply.
The result
That is Extract Method: the inner four ifs are reportHighLevels, called where they were, with mainValue and stdout passed in - seven levels became three here and four there. Cmd+Option+M opens it (Ctrl+Alt+M elsewhere); AI assistants use the ek9_extract_method tool.
