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Structures vs. ClassesAt work, our development team has a development standards document that
insists Structures should never be used. I'm looking to change this standard but need a suitable argument in order to make the change. I know that Structures are value types, sit on the stack, and are generally more efficient to manipulate than reference types (i.e. Classes). Structures cannot use inheritance, the finalize method or default constructors. Can anyone think of a situation where using Structures is more suitable than using Classes? thomasfar***@gmail.com wrote:
> At work, our development team has a development standards document Structures should be used ONLY for very small value types, so if the> that > > insists Structures should never be used. I'm looking to change this > standard but need a suitable argument in order to make the change. I > know that Structures are value types, sit on the stack, and are > generally more efficient to manipulate than reference types (i.e. > Classes). Structures cannot use inheritance, the finalize method or > default constructors. Can anyone think of a situation where using > Structures is more suitable than using Classes? struct refers to an object, it's likely not a valid candidate to be a struct. Structs have the disadvantage that if you store them in an arraylist or List<T>, manipulating them isn't as convenient as you'd think: myList[index].MyProperty = value; won't work, as you're manipulating the value you get from the indexer, not the value INSIDE the list. This can lead to bugs you only encouter at runtime, and therefore most people opt for classes instead, which is in general the right thing to do. FB -- ------------------------------------------------------------------------ Lead developer of LLBLGen Pro, the productive O/R mapper for .NET LLBLGen Pro website: http://www.llblgen.com My .NET blog: http://weblogs.asp.net/fbouma Microsoft MVP (C#) ------------------------------------------------------------------------ The only time I use structures is when two or more related simple data types
(int, boolean, string, etc.) need to be grouped together. Even in this case, I tend to use classes because I can easily change a public property into a private property with a public property SET/GET block of code that cleans up the data. Also, structures don't have a constructor to allow for default value setting. Mike Ober. <thomasfar***@gmail.com> wrote in message Show quote news:1141981479.200136.102330@j33g2000cwa.googlegroups.com... > At work, our development team has a development standards document that > > insists Structures should never be used. I'm looking to change this > standard but need a suitable argument in order to make the change. I > know that Structures are value types, sit on the stack, and are > generally more efficient to manipulate than reference types (i.e. > Classes). Structures cannot use inheritance, the finalize method or > default constructors. Can anyone think of a situation where using > Structures is more suitable than using Classes? > > > Also, structures don't have a constructor to allow for Actually, they do. See > default value setting. http://msdn.microsoft.com/library/en-us/csspec/html/vclrfcsharpspec_11_3_8.asp?frame=true -- Show quoteHTH, Kevin Spencer Microsoft MVP ..Net Developer Presuming that God is "only an idea" - Ideas exist. Therefore, God exists. "Michael D. Ober" <ober***@.alum.mit.edu.nospam> wrote in message news:etCnGkERGHA.1096@TK2MSFTNGP11.phx.gbl... > > The only time I use structures is when two or more related simple data > types > (int, boolean, string, etc.) need to be grouped together. Even in this > case, I tend to use classes because I can easily change a public property > into a private property with a public property SET/GET block of code that > cleans up the data. Also, structures don't have a constructor to allow > for > default value setting. > > Mike Ober. > > <thomasfar***@gmail.com> wrote in message > news:1141981479.200136.102330@j33g2000cwa.googlegroups.com... >> At work, our development team has a development standards document that >> >> insists Structures should never be used. I'm looking to change this >> standard but need a suitable argument in order to make the change. I >> know that Structures are value types, sit on the stack, and are >> generally more efficient to manipulate than reference types (i.e. >> Classes). Structures cannot use inheritance, the finalize method or >> default constructors. Can anyone think of a situation where using >> Structures is more suitable than using Classes? >> >> > > > Kevin - my error.
OP - Here's a link to the VB 2005 documentation that highlights the similarities and differences between classes and structures. http://msdn2.microsoft.com/en-us/library/2hkbth2a(VS.80).aspx Mike. "Kevin Spencer" <kevin@DIESPAMMERSDIEtakempis.com> wrote in message http://msdn.microsoft.com/library/en-us/csspec/html/vclrfcsharpspec_11_3_8.asp?frame=truenews:%23tXvg0ERGHA.5296@tk2msftngp13.phx.gbl... > > > Also, structures don't have a constructor to allow for > > default value setting. > > Actually, they do. See > Show quote > > -- > HTH, > > Kevin Spencer > Microsoft MVP > .Net Developer > > Presuming that God is "only an idea" - > Ideas exist. > Therefore, God exists. > > "Michael D. Ober" <ober***@.alum.mit.edu.nospam> wrote in message > news:etCnGkERGHA.1096@TK2MSFTNGP11.phx.gbl... > > > > The only time I use structures is when two or more related simple data > > types > > (int, boolean, string, etc.) need to be grouped together. Even in this > > case, I tend to use classes because I can easily change a public property > > into a private property with a public property SET/GET block of code that > > cleans up the data. Also, structures don't have a constructor to allow > > for > > default value setting. > > > > Mike Ober. > > > > <thomasfar***@gmail.com> wrote in message > > news:1141981479.200136.102330@j33g2000cwa.googlegroups.com... > >> At work, our development team has a development standards document that > >> > >> insists Structures should never be used. I'm looking to change this > >> standard but need a suitable argument in order to make the change. I > >> know that Structures are value types, sit on the stack, and are > >> generally more efficient to manipulate than reference types (i.e. > >> Classes). Structures cannot use inheritance, the finalize method or > >> default constructors. Can anyone think of a situation where using > >> Structures is more suitable than using Classes? > >> > >> > > > > > > > > > Pros:
1. Greater perf as it takes less time to allocate memory on the stack that the heap - this is miniscule, so don't use this as a reason, unless other perf tweaks have failed and you are at the end of your rope (even then, I might hang myself before switching to a struct system) 2. More deterministic clean up. The stack is guaranteed to die when the appDomain is unloaded, while the heap, technically, can live on - this is a minor benefit in most cases, as you are not in control of memory either way Cons 1. Cannot code the default constructor. If you need to spin up an object with some instantiation work, you have to have at least one parameter. This has to do with a default construct already hard wired. 2. When you use interfaces, the struct is boxed and you have to explicitly unbox it if you desire to use it as a value type. This means you lose one of the benefits of structs. Implications (neither pro or con): 1. Structs are passed, as parameters, by value. This means a new “object†is created internally. Classes are passed by reference. Depending on your system, this can be a big deal. Overall, structs are good for small "collections" of value types (implemented as properties or fields), when you do not need to add methods or adhere to an interface, like a User Defined Type (UDF), and when passing by reference does not make sense. -- Show quoteGregory A. Beamer MVP; MCP: +I, SE, SD, DBA *************************** Think Outside the Box! *************************** "thomasfar***@gmail.com" wrote: > At work, our development team has a development standards document that > > insists Structures should never be used. I'm looking to change this > standard but need a suitable argument in order to make the change. I > know that Structures are value types, sit on the stack, and are > generally more efficient to manipulate than reference types (i.e. > Classes). Structures cannot use inheritance, the finalize method or > default constructors. Can anyone think of a situation where using > Structures is more suitable than using Classes? > > Cowboy (Gregory A. Beamer) - MVP <NoSpamMgbworld@comcast.netNoSpamM>
wrote: <snip> > Implications (neither pro or con): Just for future reference - classes (objects) are *not* passed by > 1. Structs are passed, as parameters, by value. This means a new ?object? is > created internally. Classes are passed by reference. Depending on your > system, this can be a big deal. references by default. A *reference* is passed *by value*. There's a big difference. See http://www.pobox.com/~skeet/csharp/parameters.html (I'm picky about this because I've seen it confuse people who genuinely understand the difference between pass-by-reference and pass-by-value semantics. They hear that "objects are passed by reference" and expect things to work which don't.) -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too Like someone else mentioned,
I only use structures when I have many (> 1000 instances) of the same struct to create, and even then only when there is only one or two values that I need to place into the struct (like two strings, or an int and a string) I rarely use structs, but sometimes I opt for them if I don't need a constructor or any other fancy manipulation of the structs. Always keeping us honest, Jon! While this does seem picky, I have
(reluctantly) benefitted from your "nagging" in that it has forced me to be more accurate, and to study and understand things on a deeper level. For example, I have made a thorough study of .Net memory management, and am highly unlikely to confuse what goes on the stack and what goes on the heap ever again! From time to time, this understanding has proven invaluable to me personally. ;-) -- Show quoteKevin Spencer Microsoft MVP ..Net Developer Presuming that God is "only an idea" - Ideas exist. Therefore, God exists. "Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message news:MPG.1e7be4cf910209a098cf1c@msnews.microsoft.com... > Cowboy (Gregory A. Beamer) - MVP <NoSpamMgbworld@comcast.netNoSpamM> > wrote: > > <snip> > >> Implications (neither pro or con): >> 1. Structs are passed, as parameters, by value. This means a new ?object? >> is >> created internally. Classes are passed by reference. Depending on your >> system, this can be a big deal. > > Just for future reference - classes (objects) are *not* passed by > references by default. A *reference* is passed *by value*. There's a > big difference. > > See http://www.pobox.com/~skeet/csharp/parameters.html > > (I'm picky about this because I've seen it confuse people who genuinely > understand the difference between pass-by-reference and pass-by-value > semantics. They hear that "objects are passed by reference" and expect > things to work which don't.) > > -- > Jon Skeet - <sk***@pobox.com> > http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet > If replying to the group, please do not mail me too <thomasfar***@gmail.com> wrote:
> At work, our development team has a development standards document that Small point - structures don't always sit on the stack. They sit > insists Structures should never be used. I'm looking to change this > standard but need a suitable argument in order to make the change. I > know that Structures are value types, sit on the stack wherever the variable lives (for variables). See http://www.pobox.com/~skeet/csharp/memory.html I would suggest that you don't bother trying to change the standard until you've got a really good candidate for a value type. They do exist, but they're few and far between in my experience. -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too  |
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