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Fields vs properties

De unde a pornit totul:
De la o discutie in care se spunea ca la inceput este mai bine sa folosim field-uri si nu proprietatiile, iar in cazul in care ajungem sa avem nevoie de ele, le putem înlocuii in orice moment cu propietati.

Aici apare o problema. Din punct de vedere a framework-ului field-urile si proprietatiile sunt total diferite (sunt binar incompatibile). Din aceasta cauza o sa fim nevoiti sa recompilam toate assembly-urile care folosesc obiectul nostru.
In cazul in care folosim reflection la accesarea field-urilor trebuie modificat, deoarece modul in care proprietatiilese acceseaza este diferit.
Singurul avantaj care apare la field-uri este performanta, care poate sa fie îmbunătățita foarte mult. Totodata field-urile pot sa fie folosite ca si parametri ref sau out.
Cand se folosesc propietati se poate controla modul in care valoarea se seteaza (validare) sau se obtine (get,set). In cazul in care modifiarea unei proprietati produce modificarea altor valori, acest lucru poate sa fie foarte usor de facut cu o proprietate.
Problema s-ar pune intre proprietăți automate si field-uri publice. Din punct de vedere a implementarii, este mult mai usor sa schimbam implementarea la o proprietate daca vrem sa facem ceva mai special, fara sa fim nevoiti sa recompilam toata solutia. De exemplu sa avem private setter.
Cea ce nu putem face cu proprietati, este sa le setam o valurea de default in mod automat. Acest lucru trebuie facut in constructor sau intr-o metoda de initializare.
  • Ca si concluzie o sa enumar avantajele pe care le avem daca folosim proprietati publice si nu field-uri publice:
  • lazy loading;
  • propietatiile pot sa arunce erori;
  • daca lucram cu data binding trebuie sa folosim propietati;
  • se poate adauga validare cand o valoare se seteaza;
  • fine-grained control (logging intr-un fisier de exemplu, validare);
  • pot sa fie virtual si se poate face overwritten;
  • pot sa apara in interfata;
Ce parere aveti? Exista un motiv pentru care am putea sa avem field-uri publice?

Comments

  1. Sunt putine cazuri in care e suficient un field public: de ex. clase care sigur vor fi folosite doar ca DTO-uri "dummy"..
    Altfel, overheadul unui property autoimplemented e neglijabil..

    ReplyDelete

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