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I've done this too (minus marking it as private), but only when the inner class needed access to some private members of the container class, and the internals of the inner class was nobody else's business - including the container.
Something like that anyway. I've rarely done it, but I have.
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Every time I've embedded classes inside another class, some new requirement down the road requires I remove this embedded class and make it stand on its own.
I will occasionally put two classes in a file, especially when one is the <type t=""> for a custom collection class. The collection class is usually very short (<40 lines) and I put it at the top of the file so both classes are visible on the first screen in the IDE.
modified 29-Apr-24 13:36pm.
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happy to see it's not just me.
The only two times I have seen this style, they both came from CS grads whiz kids. I'm now going through a lot of code from WK#1 where he forgot to initialize a bunch of variables.
Side note: I know VS2022 allows you to ignore uninitialized variables, but why in God's good name would you ever turn that off? Been burned to many times by everything working in debug and phantom failures in release.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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As a somewhat handicapped non- queen's English speaker I get puzzled by some expression.
I have done some embedded processor hobby type projects, and currently I am struggling with child classes as members of a parent class.
I do see the differences , but mixing up these terms , or inventing new one (?) is frustrating.
Does it really makes much difference not calling classes as "member of "
as are other member variables called ?
I have never seen usage of term "embedded variable "...
modified 29-Apr-24 22:23pm.
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Different languages have different terms that are the same thing at an abstract level. Delphi has a concept of nested methods, which are either a function or procedure defined inside another (Delphi is based on Pascal, and this was explained in detail in a prior post). C# allows nested classes, where one class has another defined inside it. As others have said, this really should only be done if the nested/inner class is marked as private so only the outer class can access it. I'm avoiding the terms parent/child because those are usually used with inheritance, and this discussion has nothing to do with inheritance.
Embedded variable? It's a new one for me. I googled it:
Quote: An embedded variable in programming is not predetermined and changes, so it can't be entered ahead of time.
Bond
Keep all things as simple as possible, but no simpler. -said someone, somewhere
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embedded as a synonym for interior/inside/nested.
Java calls them inner classes.
Parent/Child class or super/sub class is more of a family tree related to class inheritance.
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yeah, I can see where the discussion mangled the concept.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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yes and I will do it again I tells you!
Enum class part of another, or groups of classes that linked, mainly object model and not really any functions/methods inside.
My mind views it like the document plan, its one piece of paper the defines the object, so why would I want to have multiple pieces of paper, individually they are useless
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Yes. exempli gratia a method returns data related to the class. What better way than via a class. What better place to declare the returned class than embedded.
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charlieg wrote: do you embed classes within classes? Yes, if appropriate. The maxim "the right tool for the job" applies.
I manage visibility with private /protected as necessary if the embedded class is only used internally by the surrounding class. An example would be elements in a data structure used within the surrounding class.
If an embedded class is public, then it is embedded because it has relevance only in relation to the surrounding class. The example here would be the embedded class contains properties and state of interest to users of the surrounding class and it's either cumbersome or infeasible to have the surrounding class supply those values itself.
Software Zen: delete this;
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I see that as a COMPLETE contradiction of encapsulation, but I freely admit to despising embedded classes. This might be because every series of embedded classes I have encountered show no reason to exist other than to be cute.
The code base I am working on actually has embedded classes within other classes that are all public. So my thought is wtf, why not make it obvious?
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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I mostly do C# these days. But I find that when I am designing a dialog box for a program, I usually need more than a single primitive value returned. What I seem to end up doing is writing an embedded class to handle all the returning data. I make it an embedded class because I can keep it associated with that dialog box. Using a class gives it an instance that doesn't vanish the moment the dialog closes. There have been a few occasions when I've decided that an embedded class was a good solution as a class to handle multiple issues in a project. When I get to that point, I usually elect to change the class from embedded to a separate file.
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Question: explain to me how putting data in an embedded class solves any problem? If the instance of the dialog (which is an object) sticks around, then the public data is still available. Embedding an object within an object seems over complicated to me. Double encapsulation?
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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I'll have to look at some of my project code and get back with you, as it half past midnight here, and I am a bit fuzzy on why. I know that the way I write my dialogs aren't quite as trivial as textbook examples, and I have to look and see why. But what I think I was doing was not so much as embedded a class within a class, but simply putting my data class on the end of the dialogbox class, initially, rather than having a separate file for the data class. It may relate to my wanting a dialog box that had an Apply button implemented in addition to the usual OK and Cancel buttons. It may be that my dialog box does something complicated and has to stay open and effect the target form with changes as I make them on the dialog without closing and reopening the dialog repeatedly until I get the combination I want.
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Okay, I'm feeling your direction. It seems like you separate all of your dialog processing from any data processing. MVC light? Anyway, my dialogs tend to just do things. The times I need to obtain data from a dialog, I'll either make it publicly available or add a wrapper method to the dialog class.
Interested in your follow up comments.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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Perhaps a dialog's returning a custom data class wasn't the best argument. I think I have a better argument for an embedded class, anyway. I'm working on a class that programmatically displays rectangles of specific color samples, and the user is expected to click on the particular rectangle to select a color. OK, nothing special about that. I am displaying the colors in a matrix of rectangles that are programmatically generated panels, given a generic List of colors that I want to present. After I got deep into the coding, I decided I wanted to have a border around every rectangle, where the color of the border signified which palette the color was in. Not that there are expected to be a lot of palettes, maybe 1, 2 or 3. But I ran into a problem: the panel control doesn't have a means to define the color of it's border. I posed that problem to ChatGPT, and it suggested I write a custom Panel class that extends the standard panel class and showed me how I could override paint to put a border of any specified color around the Panels I am creating. I don't plan to use this custom panel class anywhere else, it is short and to the point, and there seems no reason yet for having it in a stand-alone file.
Steve
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okay, I can see that a private class that is used in that one location. what I'm fighting with is that everything is public.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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I always try to use the right tool for the right job.
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I agree, but what I am seeing is a coding style vs a design approach.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
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Actually, I often do. A classic example is defining an Iterator class for a container type. It makes more sense to have the Iterator class definition be part of the container class definition (and hence called MyVector::Iterator, for example, than to create a separate MyVectorIterator, and typedef the Iterator type in MyVector.
Another example is a Pimpl pattern, although in this case the embedded class is just a declaration on the public interface, and the actual definition is in the implementation file.
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Only if there is a specific reason to do so.
One use case is that there are a lot of friends of the main class but I want tighter control over users of the embedded class.
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Statement 1: Every rule has an exception.
Statement 2: Statement 1 is a rule. Therefore Statement 1 has an exception.
Conclusion: There is at least one rule which has no exception.
Would you agree with this conclusion? If so, is there any example of a rule having no exception?
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Friends don't let friends program in Basic.
If you can't find time to do it right the first time, how are you going to find time to do it again?
PartsBin an Electronics Part Organizer - Release Version 1.4.0 (Many new features) JaxCoder.com
Latest Article: EventAggregator
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Kurt Gödel proved a version of Statement 1:
In any formal language, there are questions that can be asked but not answered.
A perfect example of Gödel's incompleteness law can be found in math:
- Positive Integers (lengths) can subtract a larger number from a smaller number. The answer is a negative integer, leading to:
- All integers can divide and result in a fraction, leading to:
- Fractions can be used in geometry to result in real numbers, leading to:
- Real Numbers can have square roots that are imaginary, leading to:
- Complex numbers, etc...
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I always think of Godel’s Completeness/Incompleteness theorems when people invent new encoding systems, etc.
XML : How do I encode “<“?
<
Well how do I encode ampersand?
&
etc.
CSV How do you encode a comma?
Enclose it in quotes.
How do you encode a quote?
Double it!
My practical interpretation:
Define a system: There will always be something outside of its boundaries!
My favorite example is good old
int getc();
It returns a char or -1 for EOF/End of File. EOF is outside of the char system.
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