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I am working to build up a GPIB : VISA driver for the IVI and NI models. There is very spare code examples and documentation without some guidance is difficult. Can anyone point me in the right direction. Note the older NationalInstrument.VISANS driver will no longer compile or work under VS2019.
If you have any example code that would be cool.
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This is why I don't use the NI NET assemblies: the good old Visa32.dll (C/C++ style, not NET) didn't change since probably 20 years and does not depend on the VS version because it binds at runtime only  (NB. see answer to your question about my article/software). It is less user friendly than IVI though, I admit.
modified 1-Jul-20 0:56am.
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For the next C# version I would like the ability to have multiple classes with the same name.
But, this is for POCO's
What do I mean?
I have an poco with the name CandidateFunction
public class CandidateFunction
{
public int CandidateFunctionId { get; set; }
public int CandidateId { get; set; }
public int FunctionId { get; set; }
public string Skills { get; set; }
public DateTime Date { get; set; }
}
As you can see, the property with the name Skills is a string.
It can be a long string and it stores one or more Skills.
But customers want to see Skills as a list so I have another POCO
public class CandidateFunctionWithSkillsList
{
public int CandidateFunctionId { get; set; }
public int CandidateId { get; set; }
public int FunctionId { get; set; }
public List<Skill> Skills { get; set; }
public DateTime Date { get; set; }
}
It has another name.
Now, I want both POCO's with the same name. I know there alternatives for what I want but I don't like them.
So, when I instantiate a new CandidateFunction, I want a popup asking me which one I want to use.
Will this ever happen and if not, why not?
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Wiep Corbier wrote: Will this ever happen and if not, why not?
No, because you create a instances of your class at run-time, and you don't want the user to be presented with a pop-up when your application is running asking them to pick which class to instantiate.
You can already have different classes with the same name if they're in different namespaces.
You can have different classes with the same name and namespace if they're in different assemblies, with no reference between the two. But they're an absolute pain to use. You have to create an "external alias" for each reference in order to disambiguate them.
Computers aren't magic. They can't "guess" which class you meant to use. And if two classes have the same name in the same namespace, with no "external alias" to disambiguate them, then there is no way for the computer to uniquely represent the class you want to use.
"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: Computers aren't magic. They can't "guess" which class you meant to use.
But anything else computers can guess?
It's not up to me to solve this problem. That's up to the people that invent new possibilities for c#.
I think it can happen but no one has ever ask this option.
So, get things done, make it happen.
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But that's the point - it's not a problem. Nobody is seriously asking for the ability to have multiple classes with the same name in the same namespace in the same assembly. It just makes no sense.
Imagine everyone in your office was called Wiep. If you put a message up on the wall saying "Wiep, call me urgently! - Wiep", would anyone have the first clue who was supposed to call whom? It would just be utter chaos. You'd have to find some way to disambiguate your names in order to 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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The point is Richard, I understand the problems.
But imagine this. You work in a office room with a colleguea also called Richard.
A person walkes in and asks for Richard. People will ask, which Richard? (popup intelli)
Got it?
I know it doesn't work yet, and I know why.
I just want it to work in the future.
ps. C# (8?) now has the ability to work around null values in classes.
Who asked for that? I didn't.
Who cares? No one.
But it's there anyway.
Just....progress
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Wiep Corbier wrote: People will ask, which Richard?
There has to be some way to disambiguate the two people. Usually you would use the surname.
It's no different with classes. If you have two classes with the same name, then they have to be in different namespaces so that you can disambiguate them.
Otherwise, even if you could come up with an intellisense popup to let you pick a class - which could be difficult if the only difference is one character on line 42! - there would be no way to represent that choice in the compiled program.
And before you suggest that the compiler could generate some form of "mangled" name to uniquely identify the class, remember that you'd also have to represent that choice in the source code. And the source code is meant to be read by humans. There are enough arguments against using var when the type isn't clear, without making an explicit variable type ambiguous as well!
Wiep Corbier wrote: C# (8?) now has the ability to work around null values in classes.
Who asked for that? I didn't.
Who cares? No one.
Lots of people asked for it, and lots of people care. You can probably find the history in the C# Language Design repository:
GitHub - dotnet/csharplang: The official repo for the design of the C# programming language[^]
"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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Richard Deeming wrote: There has to be some way to disambiguate the two people. Usually you would use the surname.
Doesn't always work. In my family history, there is a case of three boys, born of the same parents, two of them in the same year, all with the same name. The first one was born shortly after New Year, but lived for only a few days - long enough to be baptized. The second one was born in December the same year, and lived for about a year. The third one, born a couple of years later, grew up to an adult.
When I looked up the name of their paternal grandfather, I was not very surprised: The three boys were named after him. In those days, having a heir to carry your name on, one who grew up to carry the lineage on, was essential.
But I digress.
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It would still be very confusing if they had all made it to a family gathering. You'd have to resort to pointing at the person you meant.
"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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For two of them it would be pointing towards the graveyard. They never lived at the same time.
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Richard, I know that what I want isn't possible.
That's the reason why I post this.
It is a nice to have for me and probably someone else.
But what about something else like it: inheritance.
Why?
Are people to lazy to copy properties?
inheritance is not a must. It is a nice to have.
btw: I did predict you would mention the surname
Richard?
Which Richard?
Richard String or Richard List?
ps: just for fun.
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Inheritance is a useful tool for encapsulating state and/or behaviour. It can be overused, but at the moment in C# it doesn't introduce any contradictions or ambiguity. C# doesn't have multiple inheritance, so it doesn't suffer from the "diamond problem"[^].
I'm still struggling to see what problem you think your idea would solve. All I can see is code where I can't tell whether you meant this FooBar.Baz class, or that FooBar.Baz class, because they both have identical names.
"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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Wiep Corbier wrote: It is a nice to have for me and probably someone else.
Not really. Even if the feature were there, when you went back a day later and looked at your code you'd have no idea which class the code was referring to.
Social Media - A platform that makes it easier for the crazies to find each other.
Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.
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Richard Deeming wrote: There has to be some way to disambiguate the two people.
I think the OP is asking for the computer to do that. In other words I write
SomeClass temp = new SomeClass();
and up pops some intellisense so that I can pick SomeClass from file1 or SomeClass from file2. Internally, C# would clearly have to track which one it is. Which makes this idea even worse because if you come back the next day to read your code you won't know which one it actually refers to.
It could be done, and probably not too hard with some sort of internal tracker in VS but a terrible idea regardless. 
Social Media - A platform that makes it easier for the crazies to find each other.
Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.
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Wiep Corbier wrote: A person walkes in and asks for Richard. People will ask, which Richard? (popup intelli)
OK, how is the compiler going to "popup a dialog" to ask which version of the class you want when you try to "new it up"?
CandidateFunction newCandidate = new CandidateFunction()
WHICH "CandidateFunction" does the code "new up"? How is it going to know? There's no way for the compiler or the code to generate a prompt to ask. Even if it was possible, the UI type of the app comes into play. Is this a Console app? Windows Forms? WPF? ASP.NET? Each handles prompting the user is different ways, so how is the compiler to know which to use?
Oh, and how about apps with no user interface at all, like Window Services and WebAPI? How is that prompt supposed to show up?
This would have to be prompted for at compile-time. There's absolutely no way to do this at run-time.
On top of that, how is the compiler to know which type of object it is when you go to use that object elsewhere?
Did you really think about this before posting? If you want this, then it's your skill set that needs to be improved, not the compiler.
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Wiep Corbier wrote: But imagine this. You work in a office room with a colleguea also called Richard.
A person walkes in and asks for Richard. People will ask, which Richard? (popup intelli)
Got it?
I think he got it at the very beginning.
But at which point do you want the intelli pop up to come?
At compiling time... ok, do you know with of the functions is needed in each 62 places where the name is used?
Maybe you do now... but then you go to another project and then you have to make some additions 3 or 4 years later... or you leave and another guy gets in your project... or the project is so big that there are several people working on the same area at the same time... good luck when compiling (and don't forget to start one hour before the test because you will need some time to click all popups).
At execution time... how will the user know, which class is the one needed? Ok, maybe your user knows it, but how will my user know it? Or the new customer's employee.
What are the consequences of a bad selection? Good if I see I have selected the wrong option soon enough, but what if they don't realize it? Are the differences between the classes compatible? Will you need plausibility checks? How can you choose which plausibility check is needed each time?
it is already difficult enough to get the exact result you (and they) want as it is, if you add ambiguity on top... I don't even want to imagine it.
M.D.V. 
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpful answers is nice, but saying thanks can be even nicer.
modified 22-Jun-20 12:30pm.
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No.
Because - frankly - it's a dumb idea. Selecting class types at run time based on what the user decides is a recipe for convoluted, messy code that doesn;t work well in practice because users are not developers. That means that have no idea what a class is, or why they want to select one.
If you want users to decide what to create, ask them "Do you want a Candidate, or a Candidate with skills?" and explain what the difference is in their terms and what effect the decision will have. You cannot "leave that to the system" and get them to choose based on two similar names.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Wiep Corbier wrote: Will this ever happen and if not, why not?
I hope not. There is enough confusion in programming languages without adding to it.
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What this, another Richard?
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Yes, but if you check my full name you will find I am different from the other one (he knows much more than me).
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So, it is possible to have more than one Richard. 
Maybe this could be true for Classes. Not yet, in the future. ![Java | [Coffee]](https://www.codeproject.com/script/Forums/Images/coffee.gif)
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