Code Puzzler: How quickly can you figure out why this acting "weird"?
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And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
No interest to solve the puzzle. For me it goes in the same direction like "Code Puzzler vs. Dumbing down code so it can be maintained by junior devs". Do we really Need to write code where we Need first to solve a puzzle to get what the code is doing :doh: :confused:
It does not solve my Problem, but it answers my question
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No interest to solve the puzzle. For me it goes in the same direction like "Code Puzzler vs. Dumbing down code so it can be maintained by junior devs". Do we really Need to write code where we Need first to solve a puzzle to get what the code is doing :doh: :confused:
It does not solve my Problem, but it answers my question
0x01AA wrote:
Do we really Need to write code where we Need first to solve a puzzle to get what the code is doing
Well, this is different. It's a stupid bug on my part. But it's like language. If you can speak at more than a 3rd grade level, you can express your thoughts better. ;)
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
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0x01AA wrote:
Do we really Need to write code where we Need first to solve a puzzle to get what the code is doing
Well, this is different. It's a stupid bug on my part. But it's like language. If you can speak at more than a 3rd grade level, you can express your thoughts better. ;)
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
Quote:
If you can speak at more than a 3rd grade level, you can express your thoughts better
No idea what this means, sounds only I'm undeveloped :sigh: Btw. I'm aware, I'm most probably not able to solve the puzzle
It does not solve my Problem, but it answers my question
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And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
Roughly 90 seconds, mostly working out which
Console.WriteLinecall was which. :) Spoilers ahead - select the block to view:Take a copy of the static field; Create a new instance, thus overwriting the static field; Compare the new instance to the copy of the old value of the static field - result = false; Compare the new instance to the current value of the static field - result = true;
Damnit Chris, we need a
<div class="spoiler">!
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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Quote:
If you can speak at more than a 3rd grade level, you can express your thoughts better
No idea what this means, sounds only I'm undeveloped :sigh: Btw. I'm aware, I'm most probably not able to solve the puzzle
It does not solve my Problem, but it answers my question
You probably could, with a bit of thinking about it - it's obvious when you see it, but it's a stinker to spot if you didn't write the code (and probably even harder if you did if you are anything like me: I tend to see what I meant to write, rather than what I did :-O )
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay... AntiTwitter: @DalekDave is now a follower!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt -
Roughly 90 seconds, mostly working out which
Console.WriteLinecall was which. :) Spoilers ahead - select the block to view:Take a copy of the static field; Create a new instance, thus overwriting the static field; Compare the new instance to the copy of the old value of the static field - result = false; Compare the new instance to the current value of the static field - result = true;
Damnit Chris, we need a
<div class="spoiler">!
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
Is it a problem? Does it need to be fixed? :confused: I wouldn't presume to say that you didn't write exactly what you intended. Setting a
staticon each instantiation is unusual though. -
And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
The problem is that you're assigning a static variable inside the instance constructor to that instance . So every time you create an object you're changing the
Contextproperty. The reason the tests are different is because you pass theContextas a parameter so even after the update the parameter still has the oldContext. A fix would be to not do that because it's bad design ;P I'd makeContextan instance property and implement your own ==, !=, Equals, etc unless you want referential equality. -
And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
Just read the blog post, and I don't think your fix will work. :)
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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Just read the blog post, and I don't think your fix will work. :)
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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It will work in that specific example because he also changed the
CreateInstancecall to not useconnanymore. But yes, if the parameterized constructor is called it'll still have the same issue :thumbsup:Well, it will "work", in the sense that it won't overwrite the static instance. But it won't work, in the sense that the returned instance will be using the default connection string for the context, not the connection string from the instance passed in. :)
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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Roughly 90 seconds, mostly working out which
Console.WriteLinecall was which. :) Spoilers ahead - select the block to view:Take a copy of the static field; Create a new instance, thus overwriting the static field; Compare the new instance to the copy of the old value of the static field - result = false; Compare the new instance to the current value of the static field - result = true;
Damnit Chris, we need a
<div class="spoiler">!
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
Richard Deeming wrote:
select the block to view:
Now THAT is snazzy!
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
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Well, it will "work", in the sense that it won't overwrite the static instance. But it won't work, in the sense that the returned instance will be using the default connection string for the context, not the connection string from the instance passed in. :)
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
Richard Deeming wrote:
But it won't work, in the sense that the returned instance will be using the default connection string for the context, not the connection string from the instance passed in.
Hmm. But the parameterless constructor uses the connection string of the (hopefully) already initialized context:
public ModelDataContext() : base(Context.Connection)However, it's a moot point anyways as I refactored the whole mess into something much less weird. It'll be an interesting question though to pose to a couple of the devs at work, though I'll reduce the complexity of it omitting the DataContext base class - it's rather superfluous to the example.Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
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Richard Deeming wrote:
But it won't work, in the sense that the returned instance will be using the default connection string for the context, not the connection string from the instance passed in.
Hmm. But the parameterless constructor uses the connection string of the (hopefully) already initialized context:
public ModelDataContext() : base(Context.Connection)However, it's a moot point anyways as I refactored the whole mess into something much less weird. It'll be an interesting question though to pose to a couple of the devs at work, though I'll reduce the complexity of it omitting the DataContext base class - it's rather superfluous to the example.Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
OK, so it's not quite as bad as I though. :) You could still break it though:
var context1 = new ModelDataContext(new SqlConnection("server=A;database=B"));
var context2 = new ModelDataContext(new SqlConnection("server=C;database=D"));CreateNewContext(context1, out var newConn, out var newContext);
// As expected:
Console.WriteLine(newConn.ConnectionString == context1.Connection.ConnectionString); // True// Not as expected:
Console.WriteLine(newContext.Connection.ConnectionString == context1.Connection.ConnectionString); // False
Console.WriteLine(newContext.Connection.ConnectionString == newConn.ConnectionString); // False
Console.WriteLine(newContext.Connection == newConn); // False// Also not as expected:
Console.WriteLine(newContext.Connection.ConnectionString == context2.Connection.ConnectionString); // True
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
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You probably could, with a bit of thinking about it - it's obvious when you see it, but it's a stinker to spot if you didn't write the code (and probably even harder if you did if you are anything like me: I tend to see what I meant to write, rather than what I did :-O )
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay... AntiTwitter: @DalekDave is now a follower!
I also see what I meant to write as opposed to what I actually wrote. I've been tired and looked at two spellings of same word and get compiler errors and don't spot the error for some time.
Everyone has a photographic memory; some just don't have film. Steven Wright
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I also see what I meant to write as opposed to what I actually wrote. I've been tired and looked at two spellings of same word and get compiler errors and don't spot the error for some time.
Everyone has a photographic memory; some just don't have film. Steven Wright
Annoying, isn't it? :-D
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay... AntiTwitter: @DalekDave is now a follower!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt -
Annoying, isn't it? :-D
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay... AntiTwitter: @DalekDave is now a follower!
Yes very frustrating. As I get older it seems to be more prevalent.
Everyone has a photographic memory; some just don't have film. Steven Wright
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OK, so it's not quite as bad as I though. :) You could still break it though:
var context1 = new ModelDataContext(new SqlConnection("server=A;database=B"));
var context2 = new ModelDataContext(new SqlConnection("server=C;database=D"));CreateNewContext(context1, out var newConn, out var newContext);
// As expected:
Console.WriteLine(newConn.ConnectionString == context1.Connection.ConnectionString); // True// Not as expected:
Console.WriteLine(newContext.Connection.ConnectionString == context1.Connection.ConnectionString); // False
Console.WriteLine(newContext.Connection.ConnectionString == newConn.ConnectionString); // False
Console.WriteLine(newContext.Connection == newConn); // False// Also not as expected:
Console.WriteLine(newContext.Connection.ConnectionString == context2.Connection.ConnectionString); // True
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer
Richard Deeming wrote:
You could still break it though:
Yeah, but it's never used that way - two different connection strings. But ideally, it shouldn't be possible to use it that way. Sigh. The irony of this is that it's code I wrote a while back that my DataContext extension methods rely on, and looking at this now, it's some serious code smell. Fortunately, fixing it affects only a couple web servers that are in operation, but I feel embarrassed. But I blame .NET's DataContext. :laugh: It does way to much with regards to the state of the Table object. I get what they're trying to do, but there must be a better way that doesn't end up throwing exceptions like "this object was created in a different data context."
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
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And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
The reason for the results are pretty obvious, when a new instance is created in "CreateNewContext", the parameter "context" is still referring to the original context, not the new one ==> false; When the main program does the compare afterwards, the comparison is done to the static that holds the new context ==> true. Fixing this is not obvious because you didn't specify what the correct behavior should be. Do you wish it to be "True" always, or "False" always :) Simply update the context parameter in the method to get True always, but I would personally recommend to re-write this whole thing, it is full of code smells. Perhaps some practice in TDD would also be helpful. Cheers, Anthony
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And no, this isn't a programming question in the lounge. I started asking this question in the QA forum because it had me totally stumped. As I was filling out the "What I've tried" I had a major :doh: :doh: :doh: :doh: moment. To prove I'm not asking for help on the lounge, I posted a solution on [my blog](https://marcclifton.wordpress.com/2018/05/31/the-fix/). You'll need to use the password "fizbin" as the blog post is specifically for this lounge post and eventually I'll delete the post. It is a fun one though. Here's the code:
public class ModelDataContext : DataContext { public static ModelDataContext Context; public ModelDataContext(DbConnection conn) : base(conn) { Context = this; } } class Program { static ModelDataContext mdc = new ModelDataContext(new SqlConnection("\[some string\]")); static void CreateNewContext(DataContext context, out SqlConnection conn, out DataContext newContext) { conn = new SqlConnection(context.Connection.ConnectionString); newContext = (DataContext)Activator.CreateInstance(context.GetType(), new object\[\] { conn }); Console.WriteLine(context == newContext); } static void Main(string\[\] args) { SqlConnection conn2; DataContext newdc; CreateNewContext(ModelDataContext.Context, out conn2, out newdc); Console.WriteLine(ModelDataContext.Context == newdc); } }and the result is: False True Why is the second equality True when the first is False??? And for the bonus prize, what's a fix?
Latest Article - Building a Prototype Web-Based Diagramming Tool with SVG and Javascript Learning to code with python is like learning to swim with those little arm floaties. It gives you undeserved confidence and will eventually drown you. - DangerBunny Artificial intelligence is the only remedy for natural stupidity. - CDP1802
It took about a minute to solve. Assigning over the static for each constructor call is a WTF (as others have called out). Way too many statics in this Program, if it was rewritten to eliminate all of the statics, then the Program instance would hold a single context and the Main would look like this:
Main(...)
{
new Program().Run();
}If new instances of the "context" are really needed, then create a Copy constructor to reuse the default context settings on a new instance. Or use your favorite IOC container.
