C#•3mo ago

✅ using

I keep seeing variables defined within a using, like

using(var connection = new SQLiteConnection()){
...

using(var connection = new SQLiteConnection()){
...

what is using? why do people use it? what are the risks of not using it? I think this just disposes of the connection variable (for sure) after its done, but i see it used mostly when dealing with databases. is there a reason for this. If my variables are within a method they get disposed at the end of the method right? How concerned should i be about this?

7 Replies

jcotton42•3mo ago

If my variables are within a method they get disposed at the end of the method right?

No @hutonahill C# does not have RAII.

hutoanhill•3mo ago

not sure what that is, but very very good to know. and very annoying is there a reason it doesent dispose at the end of the method?

jcotton42•3mo ago

I'm actually not sure if it's due to problems with escape analysis (that is, whether the compiler knows the value has "escaped" the method) or just a delibrate choice. #roslyn would be a good place to ask that question. that being said, nowadays there's a more compact syntax, no need for indenting $using huh, no tag? alright

using var connection = new SQLiteConnection();
// code here

// instead of
using (var connection = new SQLiteConnection())
{
  // code here
}

using var connection = new SQLiteConnection();
// code here

// instead of
using (var connection = new SQLiteConnection())
{
  // code here
}

in the former, the using'd var is disposed at the end of the enclosing block

hutoanhill•3mo ago

nifty. and that just disposes of connection?

jcotton42•3mo ago

well, using is for anything that implements IDisposable, the semantics of which varies by types for file streams for example, it closes the stream for SQLiteConnection, closes the connection etc.

jcotton42•3mo ago

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/using

using statement - ensure the correct use of disposable objects - C#...

Use the C# using statement or declaration to ensure the correct use of disposable objects

hutoanhill•3mo ago

great. that answers my questions. thanks

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✅ using