My Canon Pixma MX700 printer died the other day as it was printing. It just went completely dead, as if the power cord was unplugged. I tried a few things and I did in fact manage to bring it to life, but only for a couple of days. Then, it died for good.

Here is what happened.

First, I tried a different power outlet. That was not it. Then, I checked the power cord. No problem there. Then, I took out the power supply box and disconnected it from the printer, then I reconnected it and put it back in. No improvement. Then I opened up the power supply box and examined the circuit board in it.

I experienced this problem today, drive C: of my local computer “Pegasus” was not appearing on the remote computer as “C on PEGASUS” when I connected to the remote computer via Remote Desktop (Terminal Services.) All other drives of Pegasus were showing fine on the remote computer, but the one I actually needed (C:) was not. The drive did not even appear under \\tsclient in “Network Places”.

Judging by the problems reported by people from all over the world who have this problem and are searching for solutions on the interwebz, it may happen with any local resource, like printers, the clipboard, etc.

So, today it occurred to me that the C# application that I am developing is a bit too slow on startup, and I decided to throw the visual studio profiler at it to see if I have goofed up somewhere. To my astonishment, under the profiler my app ran 10 times faster. The slowness I wanted to troubleshoot was nowhere to be found.

I also tried running the release version, and as I expected it performed better than the debug version under the profiler, so the universe was still in its place, but still, I would very much like to know what the profiler did that made the debug version of my app run so much faster. For one thing, it would be a great convenience to be able to enjoy this speedup while developing; waiting for 2 instead of 20 seconds for my app to start every time I want to check something would be very good for productivity.

I had been thinking about posting this for quite some time now, and all by coincidence I happened to get a chance to mention it just the other day in an answer that I wrote to a question on Programmers-StackExchange. So, here it is in a more formal way:

If class M stores or manipulates or in any other way works with instances of destructible (disposable) class D, it may not assume the responsibility to destruct these instances, unless it is explicitly told that ownership of these instances is transferred to it. Therefore, class M must accept a boolean called ‘handoff’ as a construction-time parameter, stating whether instances of D are being handed off to it, and it can therefore destruct them when it is done with them.

Before reading any further, please read the disclaimer.

When you declare a member variable and you pre-initialize it at the same time, and then you try to re-initialize it within the constructor without ever making use of its original pre-initialized value, you receive no warning about the field having already been initialized.

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namespace Test3 
{  
    public class Test 
    {  
        public readonly string m = "m"; 
        public string n = "n"; 
        private string o = "o"; 
        protected readonly string p = "p"; 
        protected string q = "p"; 
        private string r = "r"; 

        Test() 
        {  
            m = "m2"; //Blooper: no warning about field having already been initialized. 
            n = "n2"; //Blooper: no warning about field having already been initialized. 
            o = "o2"; //Blooper: no warning about field having already been initialized. 
            p = "p2"; //Blooper: no warning about field having already been initialized. 
            q = "q2"; //Blooper: no warning about field having already been initialized. 
            r = "r2"; //Blooper: no warning about field having already been initialized. 
            o.ToLower(); //to prevent Warning CS0414: The field is assigned but its value is never used. 
            r.ToLower(); //to prevent Warning CS0414: The field is assigned but its value is never used. 
        }  
    } 
}  

This means that you may accidentally invoke complex initialization logic twice, unnecessarily wasting memory and clock cycles, and it may also lead to logic errors, if by any chance that initialization logic has side effects which are only meant to occur once. It may also confuse someone reading your code, (or even yourself looking at your code months later,) trying to figure out what’s the purpose behind the seemingly repeated initialization, before the realization sinks in that it is simply redundant. Furthermore, if the re-initialization happens to differ from the pre-initialization, a good question arises, asking which one of the two was meant to be the correct one.

Before reading any further, please read the disclaimer.

When you declare a member variable, and then you try to read it from within the constructor without having first initialized it, you receive no warning about accessing an uninitialized member. This happens even if the member is declared as readonly.

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namespace Test2  
{  
    public class Test 
    {  
        public readonly string m; 
        public string n; 
        protected readonly string o; 
        protected string p; 
        private readonly string q; 
        private string r; 

        Test() 
        {  
            m.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            n.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            o.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            p.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            q.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            r.ToUpper(); //Blooper: no warning about accessing uninitialized member. 
            q = "q"; //to prevent Warning CS0649: Field is never assigned to, and will always have its default value null 
            r = "r"; //to prevent Warning CS0649: Field is never assigned to, and will always have its default value null 
        }  
    } 
}  

Someone might argue that this is behavior is fine because the member in question is guaranteed to contain its default value. First of all, a readonly member containing its default value is completely useless. (See C# Blooper №1: No warnings about uninitialized readonly members when the class is public and the member is public, protected or protected internal.) Secondly, if the compiler is to help the developer catch potential errors and write better code, this is not a valid excuse: a different strategy is necessary.