Block Comparison in Squeak Smalltalk

Question

I program in a script and you need to compare two blocks of code as follows: (toRunBlock is an instance variable)

~~~Other code~~~
toRunBlock := [nil].
~~~Other code~~~

But at some point I need to compare it with another block of code:

(toRunBlock = [nil]) ifTrue: [
    "Run some code if toRunBlock hasn't been overwritten"
].

But this check always gives false, and I cannot find a way to check if they are equal. Can someone help me with this?

Answer 1

As @LeandroCaniglia pointed out, you do not need to compare blocks. Here are two ways to solve your problem without comparing the blocks:

 

• initialize the variable nil. In your accessor method, you initialize it lazily:

  toRunBlock
      ^ toRunBlock ifNil: [ [] ]
  

  , toRunBlock, nil, #toRunBlock , .

  :

  toRunBlock ifNil: [
      "Run some code if toRunBlock hasn't been overwritten"
  ].
  

• , , . setter, :

  toRunBlock: aBlock
      toRunBlock := aBlock.
      hasToRunBlockBeenSet := true
  

  , :

  hasToRunBlockBeenSet
      ^ hasToRunBlockBeenSet ifNil: [ false ]
  

  :

  self hasToRunBlockBeenSet ifTrue: [
      "Run some code if toRunBlock hasn't been overwritten"
  ].
  

, , .

Answer 2

BlockClosures, . , , , . ( ), , [nil] .

, , , . , [nil] , [nil] (, defaultRunBlock) RunBlock ( ) , , toRunBlock .

Object subclass: #YourClass
    instanceVariableNames: 'toRunBlock defaultRunBlock' 
        "or as class variable:"
    classVariableNames: 'DefaultRunBlock'
    poolDictionaries: ''
    category: 'Kernel-Methods'

initialize
    defaultRunBlock := [nil]

otherCode
    toRunBlock := defaultRunBlock

whereYouCompareThem
    toRunBlock == defaultRunBlock ifTrue: [ "..." ]

, toRunBlock , .

whereYouCompareThem
    toRunBlock == previousRunBlock ifTrue: [ "..." ].
    previousRunBlock := toRunBlock