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Hi all, I posted this on the General Discussion board, but it seems a little dead in there. Hopefully this isn't too offtopic for this board.....
I was hoping for some advice on 'best practices' regarding the design of an app I'm working on. It's a subscription-based web app in C#. Member data is stored in a DB table cunningly named Members. I've implemented a fairly simple Member class which essentially wraps access to a row in the table, with functions like:
static public Member FetchFromDB( int iMemberID );
public void UpdateInDB();
etc.
and getters/setters to map the contents of the Members row, like:
public DateTime ExpiryDate{ get{ return _expiryDate; } }
public StatusEnum Status{ get{ return _status; } }
etc.
I'm happy with this class as described so far. It does one job, maintains a constant level of abstraction/encapsulation, etc. However, My app also needs functionality like 'Check whether a member's ExpiryDate is in the past, and if so update their Status to Expired', or 'Update LastOnline to now'.
The way I've been doing this so far is to add methods to Member such as UpdateLastOnlineToNow(), CheckExpiryDate(), etc. Obviously this works fine, but I'm finding myself adding more and more 'utility' methods to Member, and I'm starting to think that Member has a 'bad smell' - it's still a wrapper for the DB, but it's also getting more and more higher-level functionality mixed into it.
This class is just an example, I'm also getting similar bad smells with various similar classes in my app (Message, for example, which encapsulates my message sending/receiving system).
So my question is, what do all you wise and esteemed CPians think? Have I been reading my Patterns books a bit too religiously? If I not, what would be the best way to refactor this? One thought I had is to break Member out into 3 classes, a low-level wrapper to the DB, a high-level wrapper that uses the low-level wrapper internally, and a utility class that also uses the low-level wrapper. Is this overkill?
Any other suggestions (or any thoughts at all) gratefully appreciated!
Cheers,
Pete
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I suppose it all depends on the coder's style. I'd do it this way:
1. I would create a Member class which would be an abstraction of a "real life" Member, or in other words, a Member object. It would have all the cunningly named strongly typed properties like string Name, int Id, date ExpirationDate, etc, and not much else. U could even make it a struct, but if it gets passed around a lot, it might be better to keep it as a class.
2. Then I would create a DBManager Class that would fetch, insert and update Member instances from/into the DB. This would be like your barebone original Member class but all methods/properties would be strongly typed to the Member class when necesarry:
public Member GetMember(int memberId)
{
}
public void UpdateMember(Member changedMember)
{
}
etc...
3. And finally I would create a utility class that would perform all the functionalities upon the Member instances such as the ones you mentioned above: "UpdateLastOnLine", etc. All changes in the member instance would then be updated into the DB through the DBManager.
public void UpdateLastOnLine(Memeber member)
{
}
etc...
Hope this helps....if not quite your coding style, it might still give u some ideas. It might be an overkill for the true requirements of your app, but I always try to make my stuff in a orderly and structured fashion, even if its really not necessary.
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Hi Skynyrd,
Thanks for the response.
To clarify, the DBManager would just be responsible for wrapping the Member table in the DB, or wrapping all the tables?
I'm also not sure how the coupling would work with the three classes you mention. The way I see it, Member should be hiding/abstracting over some of the internal properties of a Member. For example, LastOnline shouldn't be settable, it should just be updatable to DateTime.Now. That being the case, both DBManager and the utility class would need access to the internals of Member, and I'm not sure how best to accomplish that. That was why I thought of having a low-level wrapper (which would expose those internals), and then a higher-level wrapper, which would be, as you say, a Member 'object'. But with that design, I'm not sure if it's feasible to have a seperate utility class. The utility class would need access to the internals, but the client of the utility class presumably wouldn't be able to access them. If this were C++, I'd consider making the utility class a friend of the lower-level wrapper, but AFAIK that isn't possible in C#.
I hope you don't think I'm being argumentative about this, I'm honestly just trying to figure the best way to design this sucker. I do appreciate your input!
And yes, as you say, all of this probably /is/ overkill for the app, but like you I like to try and keep my design as clean as possible (within reason!).
Cheers,
Pete
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DBManager could be used for wrapping all tables in the DB. If ur only updating and selecting, u could still keep the class public interface pretty simple and wrap all tables. It also depends on how u are encapsulating other objects equivalent to Members. U could even use a generic object and through Reflection and Attributes obtain the properties of the objects that represent fields in your underlying DataBase tables and thus create a very decoupled DB Manager with signatures like: Update(object changedRegistry) etc. (U could create a custom TableFieldAttribute(string fieldName) to mark the properties that represent real fields in the DB tables in order to acheive this...this comes in handy if u expect using additional properties in these objects that dont necessarily represent underlying fields).
Concerning the threeway implementation, ur right about the LastOnline method, this is probably where overkill comes in :p. The utility class would not be really necessary if only these type of methods appear. Maybe u could keep the implementation to just two classes (DBManager and Member) and Member would take care of methods similar to LastOnline, as it is logical that only Member should have access to the LastOnline setter. On the other hand, if some utilities require extensive work with Member instances then the threeway solution would be plausible, keeping methods like LastOnline in the Member class as a tool for the Utility class.
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I think the DBManager concept is interesting, particularly the use of Reflection and Attributes. However, I think it /would/ be overkill in this case  Also, it could get complicated for certain things - e.g. the Member table contains pictures, which I don't want to fetch every time I get member info. Obviously, the DBManager concept could be extended to cover that kind of thing, but then we're certainly deep in overkill land.
The reservations I have with the design you suggest is that I'm still left with a Member class that's got various levels of abstraction. While on the one hand it's exposing simple getter/setters, and it's also doing higher-level abstraction utility functionality - e.g. UpdateLastOnlineToNow(), CheckExpiryDate(), UpdateWithInputFromWebForm() (I should have mentioned that one earlier I guess).
Any other suggestions  No, seriously, thanks for the input. It's been helpful. Keep it coming
Cheers,
Ptete
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I'm not sure that the Member class should not be able to perform some simple higher-level abstraction utilities. If the actions are solely meaningful to the member class, then there is no problem in implementing them in that class.
For example, LastOnline and CheckExpiryDate might be only meaningful to the member class. Thus it would be reasonable to implement it in that class, even if its a higher level abstraction. Particularly, I would implement the CheckExpiryDate() as a boolean property HasExpired (question of tastes here  ).
On the other hand, more general functionality like UpdateWithInputFromWebForm might be a more general utility that might be meaningful to more objects than Member instances and should be implemented in a Utility class. My first design wouldnt be valid anyhow, as the Utility class should not be strongly typed to the Member class, and the update could and should be done in a generalize way (again with Reflection through a Dictionary collection: property name - new value for example u could acheive this)
To make it short, what I always try to do is isolate all DB Management from the real objects I'm using in my application. In your original design, your Member class was implementing the DB update logic too, and I think thats where I would change the abstraction of the objects. Implementing the utility class depends again on how complicated your app is really going to be, but I dont think implementing high level abstractions in the Member class is a design fault if those utilities are only applicable to the Member class.
I think we need some second view about this, so any more suggestions are welcome
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There's a new possibility in the System.IO that is accesing to Port Coms: System.IO.Ports, I'm not good with delegates and I'm trying to make a program that when receives a data from the serial port makes an event:
private void Form1_Load(object sender, EventArgs e)<br />
{<br />
ptocom.ReceivedEvent +=new SerialReceivedEventHandler(ptocom_ReceivedEvent);<br />
}<br />
<br />
void ptocom_ReceivedEvent(object sender, SerialReceivedEventArgs e)<br />
{<br />
<br />
}<br />
<br />
private void button1_Click(object sender, EventArgs e)<br />
{<br />
SerialPort ptocom = new SerialPort("COM1", 9600, System.IO.Ports.Parity.None, 8, StopBits.One);<br />
string buffer = "j";<br />
ptocom.Open();<br />
ptocom.ReadTo(buffer);<br />
}
Thats all I could discover about using this new possibilities but It doesnt work, any Idea?
Juan Pablo García Coello. Electronic Engineer.
Projectist at the Electronic Dept.Instituto de Astrofísica de Canarias. Spain
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I think your problem is, that you subscribe your event handler during the handling of the Form.Load event, but the SerialPort object isn't created until button1_Click gets called or more likely is newly created there, cause otherwise the handler subscription would crash with null reference exception.
So your event handler isn't subscribed to the SerialPort object you create in click event handler and therefor doesn't fire, but to some instance created before the Form.Load event.
www.troschuetz.de
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There's a new possibility in the System.IO that is accesing to Port Coms: System.IO.Ports, I'm not good with delegates and I'm trying to make a program that when receives a data from the serial port makes and event:
private void Form1_Load(object sender, EventArgs e)<br />
{<br />
ptocom.ReceivedEvent +=new SerialReceivedEventHandler(ptocom_ReceivedEvent);<br />
}<br />
<br />
void ptocom_ReceivedEvent(object sender, SerialReceivedEventArgs e)<br />
{<br />
<br />
}<br />
<br />
private void button1_Click(object sender, EventArgs e)<br />
{<br />
SerialPort ptocom = new SerialPort("COM1", 9600, System.IO.Ports.Parity.None, 8, StopBits.One);<br />
string buffer = "j";<br />
ptocom.Open();<br />
ptocom.ReadTo(buffer);<br />
}
Thats all I could discover about using this new possibilities but It doesnt work, any Idea?
Juan Pablo García Coello. Electronic Engineer.
Projectist at the Electronic Dept.Instituto de Astrofísica de Canarias. Spain
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I'm a non expert programmer and well I'm making a program that reads from a file how many 'child' 'style1.cs' windows to open (gets a name for each one from it).
1.- So how can I create N windows 'style1.cs'?, I mean,
style1 c_1 = new style();
and being accesible for ALL the Form1 code when on_load, because if I put
public void Form1_Load(object sender, EventArgs e)
{
//Read window number and name
style c_1 = new style();
//Read window number and name
style c_2 = new style();
}
it doesnt work.
1,5.- An embarrasing question, how can I made a for loop to do it with c_x?
2.- Can I made hierachy for 'style1' windows with the Form1 without MDI, because some things as moving it with non-border doesnt work. I mean, something like
c_1.Parent = this; //non MDI (written in Form1.cs)
...
int x= c_1.Parent.Location.X; //(written in 'child'.cs)
NOTE: I dont want to use FindWindow AND because FindWindow cant be never a solution for the same program, and other, I'm sure that there is a new function in c# in some System... to do that.
Thanks for reading,
Juan Pablo García Coello. Electronic Engineer.
Tenerife, Spain.
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i made new form named form1
inside i added label1
and panel1
inside the panel i made dynamic CONTROLBOXES each is abutton ( i mean add some buttons with small loop)
i wand to hide label when click event occurs on one of the buttons
Label.visible = off
this on the click event gives me the controlBox not the form
this is the main problem.
please help me how can i know who is the father of button and who is the father of panel ???
(do i have to sent this (of the form) for each button ??
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Where did you define the event handler for the Click event? If it's defined inside your form1 class, the this keyword should give you access to the current instance of form1.
Anyway, to get the parent container of a control simply use its Parent property.
www.troschuetz.de
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Hi, everyone!
Does anyone know about speed up programs or sometimes calles speed hack for games? I just want know how makes a such program. Could someone explain the basic concept?
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There are some programs that claim to improve performance. None of them work. Windows knows how to manage memory properly to get the best performance. The basic concept of a "performance booster" app is to move memory around so that you have more physical memory available. Although this might help once in a while you'll get bottlenecks when you switch to a different app that has been transfered to the PF. So basically its best to leave everything to Windows and design your apps to perform well in the first place.
This posting is provided "AS IS" with no warranties, and confers no rights.
Alex Korchemniy
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Thanks Alex. How about some programs that makes your applications "faster". For example speedhack programs that makes your games run faster: hit faster, run faster.
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I think your talking about "trainers"? Good luck, cause what your doing is poking numbers directly into the memory space of the game itself. There are no document (from a reliable source, anyway) that will teach you how to do this. It's sort of a black art that you figure out on your own.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Well, it's not a trainer exactly. It just speed up your application. This is the program example http://www.speederxp.com/en/ .
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Don't believe everything you read. This will not give you the kind of performance kick that they would lead you to believe. You'll get, MAYBE, a 5% boost in some apps. There's only so much you can do with what's in memory. The CPU will not execute instructions any faster, and it only tweaks some settings for network communications that reduce the wasted bandwidth, which is already small to begin with. The only way you'll notice any performance gain there is if your using dial-up. Cable modem users won't see any pickup at all.
Also, notice nobody has a full review of this software?
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Hi,
just assume for one second there really where programs which would make a windows pc overall faster. Wont you think Microsoft would buy it for 547 Quatillion Dollars to integrate it into the standard windows?
And I think there is a difference between normal accelerators and speed hacks for games (although they can be bundled in one program). By the second one I understand a program which alters the normal behaviour of a program. One example: A game restricts you to only shoot once a second. This could be done by not handling key events in this given timespan. A speed hack program could now handle the keystroke and directly make the game do the fire command. This can be done even better for online games where not the server controls those things but the client app. The hack tool just needs to send the right commands to the server (without having to tackle with the client).
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Hi,
I need to convert the VB.Net application to C#.Any ideas how to do it. Anybody tried using the convertors available to do this job or one writes an app from scratch.
Thanks.
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I'm pretty sure that SharpDevelop has a VB.NET to C# code converter in it and also I think it has a converter that does the opposite.
http://www.icsharpcode.net/OpenSource/SD/[^]
I hope this helps.
Happy Programming and may God bless!
"Your coding practices might be buggy, but your code is always right."
Internet::WWW::CodeProject::bneacetp
N-Tech Productions
http://www.n-tp.com/
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We produce converters going both ways:
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Download our free Demo Edition and try it out. We provide full support for our Demo Edition.
Our converters typically convert over 99% of original lines successfully (99.98% on published Microsoft samples).
David Anton
Tangible Software Solutions
www.tangiblesoftwaresolutions.com
Home of the Instant C# VB.NET to C# Converter and the Instant VB C# to VB.NET Converter
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I have a situation where I am utilizing code from MSDN to insert XLS files into a Microsoft Access Table in a column of Ole Object using VBA and DAO. That code also provides me with a method to extract the XLS files later. This works wonderfully.
The Article is 103257, ACC: Reading, Storing, & Writing Binary Large Objects (BLOBs) http://msdn.microsoft.com/library/default.asp?url=/library/en-us/oledb/htm/oledbaccessing_blob_data.asp
I next transfer that data to a Dataset and then to SQL Server. I found the following articles on MSDN which show how to insert and extract BLOB data using Visual C#.
The Articles are
317016 How to read and write a file to or from a BLOB column by using ADO.NET and Visual C# .NET http://support.microsoft.com/default.aspx?scid=kb;en-us;317016
and
317043 How to read and write a file to and from a BLOB column by using chunking in ADO.NET and Visual C# .NET http://support.microsoft.com/kb/317043
These work on extracting XLS files which were previously inserted using C# but fail to extract readable copies from the XLS files previously inserted via VBA.
Things I have noticed.
1. The OLE Object size in Access is twice the size of the original file.
2. When the OLE Object is extracted using VBA-DAO, the file size is back to that of the original file.
2. The OLE Object size in Access is equal to the BLOB size in SQL Server.
3. When the BLOB is extracted via C# from SQL Server, the extracted file size matches the BLOB size exactly.
Please Help!
Does VBA-DAO and OLE Objects included some sort of encoding on insertion which I must replicate C#?
Paul Kennedy
Father/Son/Husband/C Programmer
What else could you ask for?
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How do I find out the version number of a .NET DLL from within that DLL?
I tried:
<br />
Assembly a = Assembly.GetAssembly(this.GetType()); <br />
<br />
object[] attrs = a.GetCustomAttributes(typeof(AssemblyVersionAttribute), true);<br />
AssemblyVersionAttribute aVersion = (AssemblyVersionAttribute)(attrs[0]);
But GetCustomAttributes returns an empty array
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