Skip to main content

Switch vs Dictionary

Revin cu cateva informatii suplimentare pe tema switch vs dictionary ca o continuare a postului


In cazul in care avem un switch simplu care nu are nevoie sa sara de la un case la altul, codul IL care se genereaza in spate o sa fie foarte simplu si rapid. Se genereaza ceva de genul:

IL_0002: ldloc.0
IL_0003: switch (
IL_0014: br.s IL_002e

Dar cand de la un case se sare la un alt case deja IL generat se complica si ar fi bine sa se faca un review la cod. Codul generat mai jos este pentru un switch care are cateva case-uri goale( au fost adaugate doar pentru ca sa avem un cod cat mai readeable) si un case ce nu are break. In cazul acesta, pierderea de performanta este de aproape 50%. Sursa:

IL_0002: ldloc.0
IL_0003: switch (
IL_002c: br.s IL_0056

Pentru cazul acesta putem folosii dictionarul cu success. Pe partea de value la dictionar, putem folosii o lista de functii, care o sa fie apelate pe rand, cand o sa avem nevoie de un switch fara break. In cazul unor flow-uri mai complexe ar trebui sa ne implementam un mecanism de workflow.

Recomandari pentru switch:

  • blocuri compacte, fiecare case sa aiba break;
  • expresia comparata sa fie de tip enum sau cu int cu valori fixe( fara intervale de genul: 1 .. 20 si 40 .. 100);
  • char in loc de string-uri( si enum in loc de char);

Daca aveti nevoie de performanta, iar continutul din case nu este complex( nu trebuie sa se apeleze si alte blocuri case la randul sau), switch-ul o sa fie mult mai performant. Dar atentie, in cazul in care in expresia de la switch avem string, folosirea unui dictionar, hashtable sau a unui switch o sa aibe rezultate asemanatoare in IL. Switch-ul o sa fie generat pentru expresii de tip string ca si un hashtable.


Popular posts from this blog

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

Fundamental Books of a Software Engineer (version 2018)

More then six years ago I wrote a blog post about fundamental books that any software engineer (developer) should read. Now it is an excellent time to update this list with new entries.

There are 5 different categories of books, that represent the recommended path. For example, you start with Coding books, after that, you read books about Programming, Design and so on.
There are some books about C++ that I recommend not because you shall know C++, only because the concepts that you can learn from it.


Writing solid codeCode completeProgramming Pearls, more programming pearls(recommended)[NEW] Introduction to Algorithms


Refactoring (M. Fowler)Pragmatic ProgrammerClean code[NEW] Software Engineering: A Practitioner's Approach[NEW] The Mythical Man-Month[NEW] The Art of Computer Programming


Applying UML and Patterns (GRASP patterns)C++ coding standards (Sutter, Alexandrescu)The C++ programming language (Stroustrup, Part IV)Object-oriented programming (Peter Coad)P…