1 / 16

Fun with Enumerators - Comprehensive Guide for Programmers

Explore the world of enumerators, iterators, and more in this detailed guide for programmers. Learn creative techniques and best practices for efficient enumerator usage. Discover tips for reusing and chaining enumerators for enhanced productivity. Delve into enumerator implementation and tackle common challenges. Take your programming skills to the next level with this informative resource.

darcel
Download Presentation

Fun with Enumerators - Comprehensive Guide for Programmers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fun with Enumerators Primož Gabrijelčič

  2. About me • Primož Gabrijelčič • http://primoz.gabrijelcic.org • programmer, MVP, writer, blogger, consultant, speaker • Blog http://thedelphigeek.com • Twitter @thedelphigeek • Skype gabr42 • LinkedIn gabr42 • GitHub gabr42 • SO gabr

  3. Books http://tiny.cc/pg-ppotl http://tiny.cc/pg-dpd http://tiny.cc/pg-dhp

  4. More books • Delphi Programming Projects by William Duarte • The Complete Guide to RAD Server by David Intersimone • Delphi Cookbook - Third Edition by Daniele Spinetti and Daniele Teti  • Delphi Memory Management For Classic And ARC Compilers by DalijaPrasnikar • Expert Delphi by PawełGłowacki • Coding in Delphi, More Coding in Delphi, Dependency Injection in Delphi by Nick Hodges • Delphi XE2 Foundations by Chris Rolliston • Delphi Succinctlyby Marco Breveglieri • http://glooscapsoftware.blogspot.com

  5. Enumerators

  6. For-in • for [var]elementincollectiondo • Iteratorpattern • collection = set string array “collection” • element =readonly!

  7. Collection enumeration • Class/interface/record: T • public function GetEnumerator(): E • E: class/interface/record • public function MoveNext(): boolean • public property Current: V, readonly • function GetCurrent: V var collection: T; for var element: E in collection do DoSomething(element);

  8. Hidden implementation var collection: T; var element: E; var enum := T.GetEnumerator; while enum.MoveNext do DoSomething(enum.Current); enum.Free; // if required var collection: T; for var element: E in collection do DoSomething(element);

  9. RTL • System.Classes.TList • System.Classes.TCollection • System.Classes.TStrings • System.Classes.TInterfaceList • System.Classes.TComponent • Vcl.Menus.TMenuItem • Vcl.ActnList.TCustomActionList • Vcl.ComCtrls.TListItems • Vcl.ComCtrls.TTreeNodes • Vcl.ComCtrls.TToolBar • Data.DB.TFields • Data.DB.TDataSet

  10. Access to private data • Enumerator needs access to private data! • Possible solutions • Enumerator “knows” about internal implementation  • Enumerator = internal class/interface/record  • Enumerator = collection itself  • Interfaces/records only!

  11. Multiple iterators • X = class/record • GetEnumerator(): XEnumerator • AnotherEnumerator(): AnotherFactory • AnotherFactory = record • GetEnumerator(): AnotherEnumerator • TDictionary<K,V> • .Keys • .Values

  12. Reusing enumerators • GetEnumerator returns existing enumerator

  13. Creative use • Chaining enumerators • Spring4D • .Skip(3).Take(10).Reverse • Enumerating external entities • Files • Network interfaces • … • Enumerating without data • Enumerator as a factory

  14. Enumerators “on the budget” • For..in works on arrays, so… • …just return TArray<T> • Slower, but simpler

  15. Q&A

More Related