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C# - How to Bypass Error cs0212 Cheaply for Programmers and Computers?

I want to process many integers in a class, so I listed them into an int* array.
int*[] pp = new int*[]{&aaa,&bbb,&ccc};
However, the compiler declined the code above with the following EXCUSE:
> You can only take the address of an unfixed expression inside of a fixed statement initializer
I know I can change the code above to avoid this error; however, we need to consider ddd and eee will join the array in the future.
public enum E {
aaa,
bbb,
ccc,
_count
}
for(int i=0;i<(int)E._count;i++)
gg[(int)E.bbb]
　
Dictionary<string,int>ppp=new Dictionary<string,int>();
ppp["aaa"]=ppp.Count;
ppp["bbb"]=ppp.Count;
ppp["ccc"]=ppp.Count;
gg[ppp["bbb"]]
These solution works, but they make the code and the execution time longer.
I also expect a nonofficial patch to the compiler or a new nonofficial C# compiler, but I have not seen an available download for many years; it seems very difficult to have one for us.
Are there better ways so that
I do not need to count the count of the array ppp.
If the code becomes long, there are only several letters longer.
The execution time does not increase much.
To add ddd and eee into the array, there are only one or two
setences for each new member.

.NET runtime is a managed execution runtime which (among other things) provides garbage collection. .NET garbage collector (GC)
not only manages the allocation and release of memory, but also transparently moves the objects around the "managed heap", blocking
the rest of your code while doing it.
It also compacts (defragments) the memory by moving longer lived objects together, and even "promoting" them into different parts of the heap, called generations, to avoid checking their status too often.
There is a bunch of memory being copied all the time without your program even realizing it. Since garbage collection is an operation that can happen at any time during the execution of your program, any pointer-related
("unsafe") operations must be done within a small scope, by telling the runtime to "pin" the objects using the fixed keyword. This prevents the GC from moving them, but only for a while.
Using pointers and unsafe code in C# is not only less safe, but also not very idiomatic for managed languages in general. If coming from a C background, you may feel like at home with these constructs, but C# has a completely different philosophy: your job as a C# programmer should be to write reliable, readable and maintenable code, and only then think about squeezing a couple of CPU cycles for performance reasons. You can use pointers from time to time in small functions, doing some very specific, time-critical code. But even then it is your duty to profile before making such optimizations. Even the most experienced programmers often fail at predicting bottlenecks before profiling.
Finally, regarding your actual code:
I don't see why you think this:
int*[] pp = new int*[] {&aaa, &bbb, &ccc};
would be any more performant than this:
int[] pp = new int[] {aaa, bbb, ccc};
On a 32-bit machine, an int and a pointer are of the same size. On a 64-bit machine, a pointer is even bigger.
Consider replacing these plain ints with a class of your own which will provide some context and additional functionality/data to each of these values. Create a new question describing the actual problem you are trying to solve (you can also use Code Review for such questions) and you will benefit from much better suggestions.

Messages types with DataFlow Blocks

I am self-training on the TPL-Dataflow, and I have read that using immutable objects for messages is the way to go.
To comply with this, I have designed specific classes for every block inputs and outputs.
Unfortunately, when I link my block each other, because the blocks input and output types are very different, it leads to a proliferation of TransformBlock:
var proc1 = new TransformBlock<proc1In,proc1Out>(...
var convertOut1toIn2 = new TransformBlock<proc1Out,proc2In>(p1 => new proc2In { ...
var proc2 = TransformBlock<proc2In,proc2Out>(...
proc1.LinkTo(convertOut1ToIn2);
convertOut1ToIn2.LinkTo(proc2);
Using Batch and Join blocks later to merge results together makes me struggle with a very messy code.
Every samples I read on the internet uses simple types as int, string... I have not found anything that deals with a bit more complex types.
I feel the urge to use single big object and pass its reference through all the blocks. Before doing this mistake, I would like to know if there is some better way to do.

After some time musing with TPL-Dataflow, it turns out that:
Envisioning Dataflow as a conveyor belt carrying manufacturing items towards different working stations where items are enriched and built is completely wrong: doing this way leads to excruciating hard concurrency issues. Dataflow is a messaging system.
Instead, I feel it better picturing it as a mesh of people who deals with external facilities to make things (IO, Database persistence, CalculationEngines...)
The problem of messages types I dealt with is easly circumvented using Tuples. In general I dislike Tuples uglyness, but in this very situation, I feel like they really fits this place.
My problem is multiple picture analysis. Instead of having Blocks passing a "Workitem" object each other and mess with it, I rather use an separate "WorkItemSupplier" class instead. This class uses a ConcurrentDictionary of WorkItems and exposes methods to deals with workitems.
This way, my blocks in Dataflow only passes the ID of a workitem each other, so they can use the WorkItemSupplier as an external facility to store/retrieves, or change the state of any workitem.
By this way, code is running way smoothier, well separated and easier to read.

Static analysis tool to check locking before access to variable

I know there are a quite a few static analysis tools for C# or .Net around. See this question for a good list of available tools. I have used some of those in the past and they have a good way of detecting problems.
I am currently looking for a way to automatically enforce some locking rules we have in our teams. For example I would like to enforce the following rules:
"Every public method that uses member foo must acquire a lock on bar"
Or
"Every call to foobar event must be outside lock to bar"
Writing custom FxCop rules, if feasible, seems rather complex. Is there any simpler way of doing it?

Multithreading is hard. Using locks is not the only way to make operations thread-safe. A developer may use non-blocking synchronization with a loop and Interlocked.CompareExchange, or some other mechanism instead. A rule can not determine if something is thread-safe.
If the purpose of rules is to ensure high quality code, I think the best way to go about this is to create a thread-safe version of your class which is simple to consume. Put checks in place that the more-complex synchronization code is only modified under code review by developers that understand multithreading.

With NDepend you could write a code rule over a LINQ query (CQLinq) that could look like:
warnif count > 0 from m in Methods where
m.IsUsing ("YourNamespace.YourClass.foo") && (
! m.IsUsing ("YourNamespace.YourClass.bar") ||
! m.IsUsing ("System.Threading.Monitor.Enter(Object)".AllowNoMatch()) ||
! m.IsUsing ("System.Threading.Monitor.Exit(Object)".AllowNoMatch()) )
select new { m, m.NbLinesOfCode }
Basically it will matches methods that uses the field foo, without using the field bar, or without calling Monitor Enter or Exit. This is not exactly what you are asking for, since you want lock explicitely on bar, but this is simple and quite close.
Notes that you can also write...
m.AssignField("YourNamespace.YourClass.foo")
... to restrict a specific write/assign field usage on foo.

One of possible solutions could be implementation of Code Contracts. You define rules, run them at compile time (so can be also integrated in your CI environment if any) and get results.
For en example of using CodeContracts like a tool for code static analys see :
Static Code Analysis and Code Contracts

Problems with adding a `lazy` keyword to C#

I would love to write code like this:
class Zebra
{
public lazy int StripeCount
{
get { return ExpensiveCountingMethodThatReallyOnlyNeedsToBeRunOnce(); }
}
}
EDIT: Why? I think it looks better than:
class Zebra
{
private Lazy<int> _StripeCount;
public Zebra()
{
this._StripeCount = new Lazy(() => ExpensiveCountingMethodThatReallyOnlyNeedsToBeRunOnce());
}
public lazy int StripeCount
{
get { return this._StripeCount.Value; }
}
}
The first time you call the property, it would run the code in the get block, and afterward would just return the value from it.
My questions:
What costs would be involved with adding this kind of keyword to the library?
What situations would this be problematic in?
Would you find this useful?
I'm not starting a crusade to get this into the next version of the library, but I am curious what kind of considerations a feature such as this should have to go through.

I am curious what kind of considerations a feature such as this should have to go through.
First off, I write a blog about this subject, amongst others. See my old blog:
http://blogs.msdn.com/b/ericlippert/
and my new blog:
http://ericlippert.com
for many articles on various aspects of language design.
Second, the C# design process is now open for view to the public, so you can see for yourself what the language design team considers when vetting new feature suggestions. See https://github.com/dotnet/roslyn/ for details.
What costs would be involved with adding this kind of keyword to the library?
It depends on a lot of things. There are, of course, no cheap, easy features. There are only less expensive, less difficult features. In general, the costs are those involving designing, specifying, implementing, testing, documenting and maintaining the feature. There are more exotic costs as well, like the opportunity cost of not doing a better feature, or the cost of choosing a feature that interacts poorly with future features we might want to add.
In this case the feature would probably be simply making the "lazy" keyword a syntactic sugar for using Lazy<T>. That's a pretty straightforward feature, not requiring a lot of fancy syntactic or semantic analysis.
What situations would this be problematic in?
I can think of a number of factors that would cause me to push back on the feature.
First off, it is not necessary; it's merely a convenient sugar. It doesn't really add new power to the language. The benefits don't seem to be worth the costs.
Second, and more importantly, it enshrines a particular kind of laziness into the language. There is more than one kind of laziness, and we might choose wrong.
How is there more than one kind of laziness? Well, think about how it would be implemented. Properties are already "lazy" in that their values are not calculated until the property is called, but you want more than that; you want a property that is called once, and then the value is cached for the next time. By "lazy" essentially you mean a memoized property. What guarantees do we need to put in place? There are many possibilities:
Possibility #1: Not threadsafe at all. If you call the property for the "first" time on two different threads, anything can happen. If you want to avoid race conditions, you have to add synchronization yourself.
Possibility #2: Threadsafe, such that two calls to the property on two different threads both call the initialization function, and then race to see who fills in the actual value in the cache. Presumably the function will return the same value on both threads, so the extra cost here is merely in the wasted extra call. But the cache is threadsafe, and doesn't block any thread. (Because the threadsafe cache can be written with low-lock or no-lock code.)
Code to implement thread safety comes at a cost, even if it is low-lock code. Is that cost acceptable? Most people write what are effectively single-threaded programs; does it seem right to add the overhead of thread safety to every single lazy property call whether it's needed or not?
Possibility #3: Threadsafe such that there is a strong guarantee that the initialization function will only be called once; there is no race on the cache. The user might have an implicit expectation that the initialization function is only called once; it might be very expensive and two calls on two different threads might be unacceptable. Implementing this kind of laziness requires full-on synchronization where it is possible that one thread blocks indefinitely while the lazy method is running on another thread. It also means there could be deadlocks if there's a lock-ordering problem with the lazy method.
That adds even more cost to the feature, a cost that is borne equally by people who do not take advantage of it (because they are writing single-threaded programs).
So how do we deal with this? We could add three features: "lazy not threadsafe", "lazy threadsafe with races" and "lazy threadsafe with blocking and maybe deadlocks". And now the feature just got a whole lot more expensive and way harder to document. This produces an enormous user education problem. Every time you give a developer a choice like this, you present them with an opportunity to write terrible bugs.
Third, the feature seems weak as stated. Why should laziness be applied merely to properties? It seems like this could be applied generally through the type system:
lazy int x = M(); // doesn't call M()
lazy int y = x + x; // doesn't add x + x
int z = y * y; // now M() is called once and cached.
// x + x is computed and cached
// y * y is computed
We try to not do small, weak features if there is a more general feature that is a natural extension of it. But now we're talking about really serious design and implementation costs.
Would you find this useful?
Personally? Not really useful. I write lots of simple low-lock lazy code mostly using Interlocked.Exchange. (I don't care if the lazy method gets run twice and one of the results discarded; my lazy methods are never that expensive.) The pattern is straightforward, I know it to be safe, there are never extra objects allocated for the delegate or the locks, and if I have something a little more complex I can always use Lazy<T> to do the work for me. It would be a small convenience.

The system library already has a class that does what you want: System.Lazy<T>
I'm sure it could be integrated into the language, but as Eric Lippert will tell you adding features to a language is not something to take lightly. Many things have to be considered, and the benefit/cost ratio needs to be very good. Since System.Lazy already handles this pretty well, I doubt we will see this anytime soon.

Do you know about the Lazy<T> class that was added in .Net 4.0?
http://sankarsan.wordpress.com/2009/10/04/laziness-in-c-4-0-lazyt/

Have you tryed / Dou you mean this?
private Lazy<int> MyExpensiveCountingValue = new Lazy<int>(new Func<int>(()=> ExpensiveCountingMethodThatReallyOnlyNeedsToBeRunOnce()));
public int StripeCount
{
get
{
return MyExpensiveCountingValue.Value;
}
}
EDIT:
after your post edit I would add that your idea is definitely more elegant, but still has the same functionallity!!!.

This is unlikely to be added to the C# language because you can easily do it yourself, even without Lazy<T>.
A simple, but not thread-safe, example:
class Zebra
{
private int? stripeCount;
public int StripeCount
{
get
{
if (this.stripeCount == null)
{
this.stripeCount = ExpensiveCountingMethodThatReallyOnlyNeedsToBeRunOnce();
}
return this.stripeCount;
}
}
}

If you don't mind using a post-compiler, CciSharp has this feature:
class Zebra {
[Lazy] public int StripeCount {
get { return ExpensiveCountingMethodThatReallyOnlyNeedsToBeRunOnce(); }
}
}

Have a look at the Lazy<T> type. Also ask Eric Lippert about adding things like this to the language, he would no doubt have a view.

How much does bytecode size impact JIT / Inlining / Performance?

I've been poking around mscorlib to see how the generic collection optimized their enumerators and I stumbled on this:
// in List<T>.Enumerator<T>
public bool MoveNext()
{
List<T> list = this.list;
if ((this.version == list._version) && (this.index < list._size))
{
this.current = list._items[this.index];
this.index++;
return true;
}
return this.MoveNextRare();
}
The stack size is 3, and the size of the bytecode should be 80 bytes. The naming of the MoveNextRare method got me on my toes and it contains an error case as well as an empty collection case, so obviously this is breaching separation of concern.
I assume the MoveNext method is split this way to optimize stack space and help the JIT, and I'd like to do the same for some of my perf bottlenecks, but without hard data, I don't want my voodoo programming turning into cargo-cult ;)
Thanks!
Florian

If you're going to think about ways in which List<T>.Enumerator is "odd" for the sake of performance, consider this first: it's a mutable struct. Feel free to recoil with horror; I know I do.
Ultimately, I wouldn't start mimicking optimisations from the BCL without benchmarking/profiling what difference they make in your specific application. It may well be appropriate for the BCL but not for you; don't forget that the BCL goes through the whole NGEN-alike service on install. The only way to find out what's appropriate for your application is to measure it.
You say you want to try the same kind of thing for your performance bottlenecks: that suggests you already know the bottlenecks, which suggests you've got some sort of measurement in place. So, try this optimisation and measure it, then see whether the gain in performance is worth the pain of readability/maintenance which goes with it.
There's nothing cargo-culty about trying something and measuring it, then making decisions based on that evidence.

Separating it into two functions has some advantages:
If the method were to be inlined, only the fast path would be inlined and the error handling would still be a function call. This prevents inlining from costing too much extra space. But 80 bytes of IL is probably still above the threshold for inlining (it was once documented as 32 bytes, don't know if it's changed since .NET 2.0).
Even if it isn't inlined, the function will be smaller and fit within the CPU's instruction cache more easily, and since the slow path is separate, it won't have to be fetched into cache every time the fast path is.
It may help the CPU branch predictor optimize for the more common path (returning true).
I think that MoveNextRare is always going to return false, but by structuring it like this it becomes a tail call, and if it's private and can only be called from here then the JIT could theoretically build a custom calling convention between these two methods that consists of just a jmp instruction with no prologue and no duplication of epilogue.