**Challenge yourself-old**
Ejercicios tomados de el capítulo homónimo del libro [Learning Object-Oriented Programming, Design with TDD in Pharo](https://files.pharo.org/books-pdfs/learning-oop/2018-04-01-LearningOOP.pdf)
# Challenge: Message identification
For each of the expressions below, fill in the answers
* What is the receiver object?
* What is the message selector?
* What is/are the argument (s)?
* What is the result returned by this expression execution?
* receiver: 3
* selector: +
* argument: 4
* result: 7
* receiver: Date
* selector: today
* result: 2025-04-23
* receiver: #('' 'World')
* selector: at : put
* argument: 1, Hello
* result: "hello" "world"
* receiver: #(1 22 333)
* selector: at
* arguments: 2
* result: 22
* receiver: # (2 33-4 67)
* selector: collect
* arguments: [ :each | each abs ]
* result: 2 33 4 67
* receiver: 25
* selector: @
* arguments: 50
* result:
* receiver: SmallInteger
* selector: maxVal
* result: 1152921504606846975
* receiver: #(a b c d e f)
* selector: includesAll
* arguments: #(f d b)
* result: true
* receiver: true
* selector: false
* result: true
* receiver: point
* selector: selectors
* result:
# Challenge: Literal objects
What kind of object does the following literal expressions refer to? It is the
same as asking what is the result of sending the class message to such ex
pressions.
Tipo de objeto: números
Tipo de objeto: números
Tipo de objeto: números
Tipo de objeto: Cadenas
Tipo de objeto: Cadenas
Tipo de objeto: Caráctares
Tipo de objeto: Caráctares
Tipo de objeto: números
# Challenge: Kind of messages
Examine the following messages and report if the message is unary, binary or
keyword-based
Tipo de mensaje: unario
Tipo de mensaje: unario
Tipo de mensaje: binario
Tipo de mensaje: unario
Tipo de mensaje: binario
Tipo de mensaje: unario
Tipo de mensaje: binario
# Challenge: Results
Examine the following expressions. What is the value returned by the execu
tion of the following expressions?
Resultado: -2
Resultado: -2
Resultado: 32
Resultado: Self second
Resultado:
Resultado: 5
Resultado: -32
Resultado: true
# Challenge: unneeded parentheses
Putting more parentheses than necessary is a good way to get started. Such
practice however leads to less readable expressions. Rewrite the following
expressions using the least number of parentheses.
Ajuste de paréntesis: x between: (pt1 x and: pt2 y)
`Ajuste de paréntesis: #(a b c d e f) asSet intersection: #(f d b) asSet`
Ajuste de paréntesis: (x isZero
ifTrue: [....]
x includes: y)
ifTrue: [....]
Ajuste de paréntesis: OrderedCollection new
add: 56;
add: 33;
yourself
Ajuste de paréntesis: (3 + 4) + (2 * 2) + (2 * 3)
Ajuste de paréntesis: Integer primesUpTo: 64 sum
'http://www.pharo.org' asUrl retrieveContents