Re: [Mono-list] Questions about coding style
On Aug 20, 2012, at 3:28 PM, Philippe Grohrock philippe.grohr...@gmail.com
wrote:
Thanks for the reply already and I'm sorry, I should've added the lines of
code.
static class GlobalVariables
{
public static MySqlConnection connection = new connection();
}
This way the whole program has access to it and can modify/query the DB when
needed (this is what I meant with global).
I believe that this is a Bad Idea™.
Firstly, this is counter to ~every MSDN example on using connections, which
always scopes the Connection instance:
//
http://msdn.microsoft.com/en-us/library/ff647768.aspx#scalenetchapt12_topic9
using (SqlConnection conn = new SqlConnection(connString))
{
conn.Open();
// ...
}
This implies that you should instead do:
static class Database {
internal static MySqlConnection CreateConnection ()
{
return new connection ();
}
}
And narrowly scope your use:
using (var c = Database.CreateConnection ()) {
c.Open ();
// ...
}
Now, _why_ should you do this? Unfortunately I can't find anything to confirm
or deny the following, but this is my recollection from using SQL many years
ago...
The reason why is connection-related errors: if (when) you hit a network
interruption, the DbConnection instance is unusable afterward, even if the
network came back. (Though maybe I needed to .Close() and .Open() to repair the
instance? I no longer remember.) I found that the easiest/sanest way to go was
to just recreate the Connection instance when needed, and Dispose() of it as
soon as possible (relying on lower-level connection pooling if possible).
- Jon
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Re: [Mono-list] Questions about coding style
To add to what Jonathan said, trying to reuse the same connection for
everything can also lead to concurrent access issues, if more than one
thread accesses the connection at a given time. I've seen such issues when
using Entity Framework. Besides, creating a new connection is really cheap.
Jonathan Pryor wrote
On Aug 20, 2012, at 3:28 PM, Philippe Grohrock lt;philippe.grohrock@gt;
wrote:
Thanks for the reply already and I'm sorry, I should've added the lines
of code.
static class GlobalVariables
{
public static MySqlConnection connection = new connection();
}
This way the whole program has access to it and can modify/query the DB
when needed (this is what I meant with global).
I believe that this is a Bad Idea™.
Firstly, this is counter to ~every MSDN example on using connections,
which always scopes the Connection instance:
//
http://msdn.microsoft.com/en-us/library/ff647768.aspx#scalenetchapt12_topic9
using (SqlConnection conn = new SqlConnection(connString))
{
conn.Open();
// ...
}
This implies that you should instead do:
static class Database {
internal static MySqlConnection CreateConnection ()
{
return new connection ();
}
}
And narrowly scope your use:
using (var c = Database.CreateConnection ()) {
c.Open ();
// ...
}
Now, _why_ should you do this? Unfortunately I can't find anything to
confirm or deny the following, but this is my recollection from using SQL
many years ago...
The reason why is connection-related errors: if (when) you hit a network
interruption, the DbConnection instance is unusable afterward, even if the
network came back. (Though maybe I needed to .Close() and .Open() to
repair the instance? I no longer remember.) I found that the
easiest/sanest way to go was to just recreate the Connection instance when
needed, and Dispose() of it as soon as possible (relying on lower-level
connection pooling if possible).
- Jon
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Re: [Mono-list] Questions about coding style
On Aug 17, 2012, at 5:49 PM, Philippe Grohrock philippe.grohr...@gmail.com wrote: 1. Is it bad/good style to have a public class that implements global variables? How do you define global variable? :-) `public static` fields are Very Bad™, unless they're `readonly`. This is because there's no way to prevent modification of the field from anything else in your process. `public static` properties are (generally) fine, and are common in the Base Class Library. Best, though, is to keep things `internal` or `private` unless they _really_ need to be public. My program readys a DB connection right at the start which is queried by multiple different GTK windows. This is a case where `internal` should normally be preferred over `public`, unless another assembly in your app needs access to the value. - Jon ___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list
Re: [Mono-list] Questions about coding style
Thanks for the reply already and I'm sorry, I should've added the lines of code. This way the whole program has access to it and can modify/query the DB when needed (this is what I meant with global). At the moment I have 2 of my windows using that connection, but there might be more in the future. So is this a bad way of doing it? Would it be better to have the connection be internal static? Should I declare it once after the start of the program and then hand it over to the windows? I think I also need to open a new topic about assemblies ;) -- View this message in context: http://mono.1490590.n4.nabble.com/Questions-about-coding-style-tp4656301p4656321.html Sent from the Mono - General mailing list archive at Nabble.com.___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list
Re: [Mono-list] Questions about coding style
I'd create ConnectionFactory class, although feel free to ignore me,
just thinking off the top of my head! :-)
public class ConnectionFactory
{
private static MySqlConnection _connection;
public MySqlConnection GetConnection()
{
if (_connection == null)
{
_connection = new MySqlConnection();
}
return _connection;
}
}
On 20/08/2012 20:28, Philippe Grohrock wrote:
Thanks for the reply already and I'm sorry, I should've added the
lines of code.
static class GlobalVariables
{
public static MySqlConnection connection = new connection();
}
This way the whole program has access to it and can modify/query the
DB when needed (this is what I meant with global). At the moment I
have 2 of my windows using that connection, but there might be more in
the future. So is this a bad way of doing it? Would it be better to
have the connection be internal static? Should I declare it once after
the start of the program and then hand it over to the windows? I think
I also need to open a new topic about assemblies ;)
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Re: [Mono-list] Questions about coding style
Just in case no-one else spots it, you'll need a static keyword on
that GetConnection() declaration, otherwise you have to create an
instance to get a reference to the private static variable, which is
just odd :)
On 20/08/12 20:45, James Wright wrote:
I'd create ConnectionFactory class, although feel free to ignore me,
just thinking off the top of my head! :-)
public class ConnectionFactory
{
private static MySqlConnection _connection;
public MySqlConnection GetConnection()
{
if (_connection == null)
{
_connection = new MySqlConnection();
}
return _connection;
}
}
On 20/08/2012 20:28, Philippe Grohrock wrote:
Thanks for the reply already and I'm sorry, I should've added the
lines of code.
static class GlobalVariables
{
public static MySqlConnection connection = new connection();
}
This way the whole program has access to it and can modify/query the
DB when needed (this is what I meant with global). At the moment I
have 2 of my windows using that connection, but there might be more in
the future. So is this a bad way of doing it? Would it be better to
have the connection be internal static? Should I declare it once after
the start of the program and then hand it over to the windows? I think
I also need to open a new topic about assemblies ;)
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Re: [Mono-list] Questions about coding style
Be carefull about this way of working with DB. You must free the connections as
fast as you can and I'm not sure you can do like this way.
What happen if you dispose the connection ? That would be the usual way of
freeing the queue (or thru the 'using' blocks).
/Gabriel
-Original Message-
From: Philippe Grohrock philippe.grohr...@gmail.com
Date: Mon, 20 Aug 2012 19:28:07
To: mono-list@lists.ximian.com
Subject: Re: [Mono-list] Questions about coding style
Thanks for the reply already and I'm sorry, I should've added the lines of
code.static class GlobalVariables{ public static
MySqlConnection connection = new connection();} This way the whole program
has access to it and can modify/query the DB when needed (this is what I meant
with global). At the moment I have 2 of my windows using that connection, but
there might be more in the future. So is this a bad way of doing it? Would it
be better to have the connection be internal static? Should I declare it once
after the start of the program and then hand it over to the windows? I think I
also need to open a new topic about assemblies ;)
View this message in context: Re: Questions about coding style
http://mono.1490590.n4.nabble.com/Questions-about-coding-style-tp4656301p4656321.html
Sent from the Mono - General mailing list archive
http://mono.1490590.n4.nabble.com/Mono-General-f1490591.html at Nabble.com.
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Re: [Mono-list] Questions about coding style
Be carefull about this way of working with DB. You must free the connections as fast as you can and I'm not sure you can do like this way. Basically the connection gets initialised when the application starts and every time I need a query, the connection gets opened, queried, closed, but not disposed. Connection.dispose() happens right before the application quits What happen if you dispose the connection ? That would be the usual way of freeing the queue (or thru the 'using' blocks). My idea was to never dispose the connection to make the code a bit lighter. That way I don't have to re-initialise the connection each time I need a single query. Instead I have one connection with pooling enabled that gets opened and closed when I need it. Now my problem is, that even there I'm not sure if this is a good way of dealing with that problem, it's just the idea to not create and dispose the connection for each query that lead me to do things this way. But in the end, does that even make a difference in terms of connection speed and resource usage? Forgive me for asking such basic questions, but when it comes to organisation of code and using resources wisely I'm still learning. -- View this message in context: http://mono.1490590.n4.nabble.com/Questions-about-coding-style-tp4656301p4656325.html Sent from the Mono - General mailing list archive at Nabble.com.___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list
Re: [Mono-list] Questions about coding style
Unless I'm mistaken .NET connections are pooled for you, so I don't think you'll be gaining much from keeping one instance of the connection always open as the framework is already doing just that. My advice is don't worry about it until you have to... chances are it won't be a problem in the real world! On 20/08/2012 22:01, Philippe Grohrock wrote: Be carefull about this way of working with DB. You must free the connections as fast as you can and I'm not sure you can do like this way. Basically the connection gets initialised when the application starts and every time I need a query, the connection gets opened, queried, closed, but not disposed. Connection.dispose() happens right before the application quits What happen if you dispose the connection ? That would be the usual way of freeing the queue (or thru the 'using' blocks). My idea was to never dispose the connection to make the code a bit lighter. That way I don't have to re-initialise the connection each time I need a single query. Instead I have one connection with pooling enabled that gets opened and closed when I need it. Now my problem is, that even there I'm not sure if this is a good way of dealing with that problem, it's just the idea to not create and dispose the connection for each query that lead me to do things this way. But in the end, does that even make a difference in terms of connection speed and resource usage? Forgive me for asking such basic questions, but when it comes to organisation of code and using resources wisely I'm still learning. View this message in context: Re: Questions about coding style http://mono.1490590.n4.nabble.com/Questions-about-coding-style-tp4656301p4656325.html Sent from the Mono - General mailing list archive http://mono.1490590.n4.nabble.com/Mono-General-f1490591.html at Nabble.com. ___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list ___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list
Re: [Mono-list] Questions about coding style
Unless I'm mistaken .NET connections are pooled for you, so I don't think you'll be gaining much from keeping one instance of the connection always open as the framework is already doing just that. My advice is don't worry about it until you have to... chances are it won't be a problem in the real world! Connections only get pooled when pooling=true is set, but as far as I understood it, this only works as long as the connection doesn't get disposed. -- View this message in context: http://mono.1490590.n4.nabble.com/Questions-about-coding-style-tp4656301p4656327.html Sent from the Mono - General mailing list archive at Nabble.com.___ Mono-list maillist - Mono-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-list
