Have you ever looked what is in those corrupted PDFs? Maybe you will find a html-site that tells you that the file wasn't found on this server or you maybe haven't the right to access to file directly.
To access files from a website that saves the login in a cookie is hard.
You have to find the cookie the website saved on your computer and send it with the HTTP-Request Header.
(I don't know an other way except the website has a possibility to login per querystring (ex. data.aspx?user=abc&pwd=pwd)).
Hello gurus and mavens!
I haven't had to post any problems here in a while - which I take to be good sign for me. And this one isn't so much a "problem" as a "question".
I thought the compiler would choke on the following code:
private G Val;
public MyClass(string initStr)
if (initStr == "bad init string")
thrownew ApplicationException("You can't do that!");
Val = default(G);
public MyClass(G initVal)
Val = initVal;
staticvoid Main(string args)
MyClass<int> example1 = new MyClass<int>("test"); // use the first constructor
MyClass<int> example2 = new MyClass<int>(1); // use the second constructor
MyClass<string> example3 = new MyClass<string>("what happens here?"); // I want the second constructor
and tell me that it did not know which constructor to use with example3 since both constructors for MyClass would accept a string. But it didn't! Instead it just elects to use the constructor with the parameter of type string. Not what I expected, and not what I wanted.
To get around this, I changed the second constructor to
public MyClass(G initVal, bool dummy)
and the call to
MyClass<string> example3 = new MyClass<string>("what happens here?", true);
just to make it clear that I want to use the second constructor.
My question is this: is there a better way to handle this that I am not aware of? Is there some hidden option or obscure construct that makes sense of ambiguous constructor signatures?
This is expected behavior. MyClass(G) when G is a string becomes MyClass(string). As a constructor with those parameter types already exists a new one is not generated by the compiler as the parameter list must be different to successfully overload.
I'd go further and say this is the desired behaviour for the generic overload (i.e. I think the .Net framework makes the correct choice). MyClass(string foo) is explicitly stating "I deal with strings" and is therefore concrete, whereas MyClass(G foo) is stating "I deal with 'G's" which is less concrete.
The design in the OP needs refactoring IMO, the concrete MyClass(string foo) ctor needs to be removed unless there is a specific reason for dealing with strings specifically. The validation performed on the strings is likely to be, but not necessarily, valid for other types.
The design in the OP needs refactoring [...] unless there is a specific reason for dealing with strings specifically.
In the actual code MyClass is a class that represents some kind of value. The first ctor (MyClass(string initStr)) is used when the initStr holds a formula that needs to be parsed and evaluated to get the value. The second ctor (MyClass(G initVal, bool dummy)) is used when the value is already known, and does not need to be parsed or evaluated. The confusion arose, of course, when the value is a known string.
I will take your recommendation to remove the first ctor into consideration, but at this point, I don't see a way for it work (is MyClass("foo()") a request for the string returned by foo or for the string "foo()"?). In the meantime, I will take it that my "workaround" is not wrong/dangerous/problematic/laughable.
The first ctor (MyClass(string initStr)) is used when the initStr holds a formula that needs to be parsed and evaluated to get the value
This is a worry*, and the source of your problem. If possible, you should defer the instantiation of this class until you have the value you want to use. If I understand you correctly, by passing the formula as a string will require the current class to be responsible for performing the parsing as well as whatever this class is meant to do with the result, this is probably bad object encapsulation.
A better way to handle this is to create an object which is responsible for the storage and parsing of the formula, and pass the results of the formula into the current class ,explained in your original post. This will separate the concerns more clearly.
* This is a worry because, unless you are parsing text entries from a user or some other source (e.g. text input from a UI or file), writing formulas in strings and then evaluating them is bad design (and a real pain. If this is the case, then it's unavoidable. If you are just using this to pass formulae around within the application, you should look at c# delegates(which allow you to pass methods around as parameters) and possibly the strategy pattern.
If I understand you correctly, by passing the formula as a string will require the current class to be responsible for performing the parsing as well as whatever this class is meant to do with the result, this is probably bad object encapsulation.
Agreed. But the class is not actually responsible for the parsing or evaluation (it passes those tasks off to another class), nor is it responsible for acting on the value. The class just holds on to expression tree created by parsing the formula and uses it to provide a value when requested. Perhaps my original example was over-simplified.
...unless you are parsing text entries from a user or some other source (e.g. text input from a UI or file), writing formulas in strings and then evaluating them is bad design...
This is exactly what I am doing. The formulas are read from user-created XML files and used to control the program's behaviour. This is fun... every criticism you offer just seems to confirm that I'm doing it correctly . Keep going, keefb... one more critique should cement that I'm the bona fide genuis that I always knew myself to be (no matter what those jerks at Mensa had to say )
I have a third party dll that is written in C++ that saves a bitmap image as the actual grayscale values and not a Bitmap format. I am looking for a way to read in the grayscale values and convert them to use C#/.NET 's Bitmap class.
Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
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