CODEWITHSUNDEEP
smalltalk
Jarda Fišer
Jarda Fišer

Reputation: 1

Message in smalltalk

I'm new to Smalltalk and i have this question.

I have written this message:

((Objednavkaset select:[:a | a auto porucha notEmpty])
    select: [:d | 
        (d auto porucha select:[:x | 
            x datum_poruchy
                between: x datum_vypujceni
                and: x datum_skutecneho_vraceni])
            size > 0])

and I have this problem, i need to access datum_vypujceni and datum_skutecneho_vraceni from this select

select: [:d | (d auto porucha select:[:x | x datum_poruchy between: x datum_vypujceni and: x datum_skutecneho_vraceni]]

but I don't know how, is there any way to access it?

Here is diagram if you need it.

diagram

Upvotes: 0

Views: 241

Answers (5)

Travis Griggs
Travis Griggs

Reputation: 22290

I'll edit as you clarify what you're really after, but I can provide this much so far...

I think your first level select: makes it harder to see things. Using anySatisfy: will automatically filter out the empty ones.

Objednavkaset select: [:eachSet | 
    eachSet auto porucha anySatisfy:[:eachPorucha | 
        eachPorucha datum_poruchy
            between: x datum_vypujceni
            and: x datum_skutecneho_vraceni]]

Upvotes: 0

Carlos E. Ferro
Carlos E. Ferro

Reputation: 948

As the innermost condition is

x datum_poruchy
       between: x datum_vypujceni
       and: x datum_skutecneho_vraceni

everything is part of the x object, so the whole condition should be there, like 

hasValidPoruchy
    ^datum_poruchy
           between: datum_vypujceni
           and: datum_skutecneho_vraceni

Upvotes: 2

Stephan Eggermont
Stephan Eggermont

Reputation: 15917

In your method you use a auto porucha and d auto porucha. That long chain suggests that some behavior might not be defined on the right object. The "Law of Demeter" suggests to reduce those chains, e.g. by defining on the object this auto refers to what the porucha anySatisfy:... actually are

Upvotes: 1

Leandro Caniglia
Leandro Caniglia

Reputation: 14843

As much as I like Uko's answer for the removal of the initial select: and the use of anySatisfy:, I think that Jarda's question still remains unanswered.

The actual question is how to access the two instance variables datum_vypujceni and datum_skutecneho_vraceni of objed, rather than how to write the selection script.

So, here is the answer to this simple question: Jarda, add two methods in your Objednavka class that answer these instance variables:

datum_vypujceni
    ^datum_vypujceni

datum_skutecneho_vraceni
    ^datum_skutecneho_vraceni

Once you have these methods, your script will get these data from your objed variable. Note also that you will need another getter to access the datum_poruchy of a Poruchy. So make sure your Poruchy class has the getter method

datum_poruchy
    ^datum_poruchy

Upvotes: 3

Uko
Uko

Reputation: 13396

What is your goal? If you want to get all Objednavka that has at least one Poruchy that has date between other dates of the Objednavka it belongs to, you can do it like this:

(Objednavkaset select: [ :objed |
    objed auto porucha anySatisfy: [ :poruchy | 
            poruchy datum_poruchy
                between: objed datum_vypujceni
                and: objed datum_skutecneho_vraceni ] ] ]

also I don't know if your smalltalk has #anySatisfy:. If not - let me know. If you code in , it definitely has

Upvotes: 2

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