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Type-Safe / Thread-SafeCan someone explain the two terms "type-safe" and "thread-safe"? I
understand what a type and a thread are, but what does it mean for them to be "safe"? Scott M. wrote:
> Can someone explain the two terms "type-safe" and "thread-safe"? I Note that these terms are differently applicable; type safety is a> understand what a type and a thread are, but what does it mean for them to > be "safe"? property of languages, whereas thread safety is a property of particular pieces of code. The wikipedia entries look OK for both: <http://en.wikipedia.org/wiki/Type_safety> <http://en.wikipedia.org/wiki/Thread_safety> -- Larry Lard Replies to group please
Show quote
"Larry Lard" <larryl***@hotmail.com> wrote in message I think that that is slightly over simplistic.news:1145376450.213200.141660@i39g2000cwa.googlegroups.com... > > Scott M. wrote: >> Can someone explain the two terms "type-safe" and "thread-safe"? I >> understand what a type and a thread are, but what does it mean for them >> to >> be "safe"? > > > Note that these terms are differently applicable; type safety is a > property of languages, whereas thread safety is a property of > particular pieces of code. The wikipedia entries look OK for both: > As the wiki says - type safety can be enforced at compile time or at runtime. C# is type safe because the runtime will not permit invalid type casting, however compile time type safety is obviously safer in than runtime type safety and from this you can expand the definition of typesafety to include coding. The obvious examples are the collections: An ArrayList intended to hold ints is type-safe only in the sense that nothing in it can be treated as an int unless it actually is one. It is not type-safe in that there is nothing to stop someone putting a string in it. List<int> is type-safe in a much stronger sense because it is type-safe at compile time rather than runtime and yet this due to the particular class rather than the language. Similarly there are gradations of thread-safety. A method may be thread safe whereas a way of using it is not. The classic example is: for(i=0; i< list.Length; ++i) { doStuff(list[i]); } This would not normally be considered thread-safe regardless of whether or not the Length property and the indexer are thread-safe. Show quote So, in VB.NET, if you had Option Strict turned on (which prevents late
binding and implicit casts), would VB.NET then be considered Type-Safe? Show quote "Nick Hounsome" <N***@NickHounsome.Me.Uk> wrote in message news:cK81g.97297$8Q3.12492@fe1.news.blueyonder.co.uk... > > "Larry Lard" <larryl***@hotmail.com> wrote in message > news:1145376450.213200.141660@i39g2000cwa.googlegroups.com... >> >> Scott M. wrote: >>> Can someone explain the two terms "type-safe" and "thread-safe"? I >>> understand what a type and a thread are, but what does it mean for them >>> to >>> be "safe"? >> >> >> Note that these terms are differently applicable; type safety is a >> property of languages, whereas thread safety is a property of >> particular pieces of code. The wikipedia entries look OK for both: >> > > I think that that is slightly over simplistic. > As the wiki says - type safety can be enforced at compile time or at > runtime. C# is type safe because the runtime will not permit invalid type > casting, however compile time type safety is obviously safer in than > runtime type safety and from this you can expand the definition of > typesafety to include coding. The obvious examples are the collections: > > An ArrayList intended to hold ints is type-safe only in the sense that > nothing in it can be treated as an int unless it actually is one. It is > not type-safe in that there is nothing to stop someone putting a string in > it. > > List<int> is type-safe in a much stronger sense because it is type-safe at > compile time rather than runtime and yet this due to the particular class > rather than the language. > >> <http://en.wikipedia.org/wiki/Type_safety> >> > > Similarly there are gradations of thread-safety. > A method may be thread safe whereas a way of using it is not. > The classic example is: > > for(i=0; i< list.Length; ++i) > { > doStuff(list[i]); > } > > This would not normally be considered thread-safe regardless of whether or > not the Length property and the indexer are thread-safe. > >> <http://en.wikipedia.org/wiki/Thread_safety> >> >> -- >> Larry Lard >> Replies to group please >> > > Yes - for the most part - especially if you are using VB 2005. VB, and the
rest of .NET, contains the "Object" type which can contain any type. However, to do anything with it, you must explicitely cast it to a different type at runtime. In VB 2005, this is done via the CType(myOjb, <target type>). Note that this cast can fail with an exception. Mike. Show quote "Scott M." <s-mar@nospam.nospam> wrote in message news:OGGubnwYGHA.4620@TK2MSFTNGP04.phx.gbl... > > So, in VB.NET, if you had Option Strict turned on (which prevents late > binding and implicit casts), would VB.NET then be considered Type-Safe? > > > "Nick Hounsome" <N***@NickHounsome.Me.Uk> wrote in message > news:cK81g.97297$8Q3.12492@fe1.news.blueyonder.co.uk... > > > > "Larry Lard" <larryl***@hotmail.com> wrote in message > > news:1145376450.213200.141660@i39g2000cwa.googlegroups.com... > >> > >> Scott M. wrote: > >>> Can someone explain the two terms "type-safe" and "thread-safe"? I > >>> understand what a type and a thread are, but what does it mean for them > >>> to > >>> be "safe"? > >> > >> > >> Note that these terms are differently applicable; type safety is a > >> property of languages, whereas thread safety is a property of > >> particular pieces of code. The wikipedia entries look OK for both: > >> > > > > I think that that is slightly over simplistic. > > As the wiki says - type safety can be enforced at compile time or at > > runtime. C# is type safe because the runtime will not permit invalid type > > casting, however compile time type safety is obviously safer in than > > runtime type safety and from this you can expand the definition of > > typesafety to include coding. The obvious examples are the collections: > > > > An ArrayList intended to hold ints is type-safe only in the sense that > > nothing in it can be treated as an int unless it actually is one. It is > > not type-safe in that there is nothing to stop someone putting a string in > > it. > > > > List<int> is type-safe in a much stronger sense because it is type-safe at > > compile time rather than runtime and yet this due to the particular class > > rather than the language. > > > >> <http://en.wikipedia.org/wiki/Type_safety> > >> > > > > Similarly there are gradations of thread-safety. > > A method may be thread safe whereas a way of using it is not. > > The classic example is: > > > > for(i=0; i< list.Length; ++i) > > { > > doStuff(list[i]); > > } > > > > This would not normally be considered thread-safe regardless of whether or > > not the Length property and the indexer are thread-safe. > > > >> <http://en.wikipedia.org/wiki/Thread_safety> > >> > >> -- > >> Larry Lard > >> Replies to group please > >> > > > > > > > How is that different than VB.NET 2003? In 2003, we use CType(sourceObj,
targetType) and DirectCast(Type, targetType). With Option Strict turned on, both should flag errors at compile time. Show quote "Michael D. Ober" <ober***@.alum.mit.edu.nospam> wrote in message news:%23uxW8vwYGHA.4168@TK2MSFTNGP05.phx.gbl... > > Yes - for the most part - especially if you are using VB 2005. VB, and > the > rest of .NET, contains the "Object" type which can contain any type. > However, to do anything with it, you must explicitely cast it to a > different > type at runtime. In VB 2005, this is done via the CType(myOjb, <target > type>). Note that this cast can fail with an exception. > > Mike. > > "Scott M." <s-mar@nospam.nospam> wrote in message > news:OGGubnwYGHA.4620@TK2MSFTNGP04.phx.gbl... >> >> So, in VB.NET, if you had Option Strict turned on (which prevents late >> binding and implicit casts), would VB.NET then be considered Type-Safe? >> >> >> "Nick Hounsome" <N***@NickHounsome.Me.Uk> wrote in message >> news:cK81g.97297$8Q3.12492@fe1.news.blueyonder.co.uk... >> > >> > "Larry Lard" <larryl***@hotmail.com> wrote in message >> > news:1145376450.213200.141660@i39g2000cwa.googlegroups.com... >> >> >> >> Scott M. wrote: >> >>> Can someone explain the two terms "type-safe" and "thread-safe"? I >> >>> understand what a type and a thread are, but what does it mean for > them >> >>> to >> >>> be "safe"? >> >> >> >> >> >> Note that these terms are differently applicable; type safety is a >> >> property of languages, whereas thread safety is a property of >> >> particular pieces of code. The wikipedia entries look OK for both: >> >> >> > >> > I think that that is slightly over simplistic. >> > As the wiki says - type safety can be enforced at compile time or at >> > runtime. C# is type safe because the runtime will not permit invalid > type >> > casting, however compile time type safety is obviously safer in than >> > runtime type safety and from this you can expand the definition of >> > typesafety to include coding. The obvious examples are the collections: >> > >> > An ArrayList intended to hold ints is type-safe only in the sense that >> > nothing in it can be treated as an int unless it actually is one. It is >> > not type-safe in that there is nothing to stop someone putting a string > in >> > it. >> > >> > List<int> is type-safe in a much stronger sense because it is type-safe > at >> > compile time rather than runtime and yet this due to the particular > class >> > rather than the language. >> > >> >> <http://en.wikipedia.org/wiki/Type_safety> >> >> >> > >> > Similarly there are gradations of thread-safety. >> > A method may be thread safe whereas a way of using it is not. >> > The classic example is: >> > >> > for(i=0; i< list.Length; ++i) >> > { >> > doStuff(list[i]); >> > } >> > >> > This would not normally be considered thread-safe regardless of whether > or >> > not the Length property and the indexer are thread-safe. >> > >> >> <http://en.wikipedia.org/wiki/Thread_safety> >> >> >> >> -- >> >> Larry Lard >> >> Replies to group please >> >> >> > >> > >> >> >> > > > Type-Safe refers to the language's ability to prevent you from doing
something like this: dim s as string dim i as integer s = "My String" i = s Preferably, this protection is done at compile time and not at run time. Thread-Safe refers to objects and methods in those objects being protected from internal corruption when multiple execution threads simultaneously update the object (or update while reading). These types of errors can be extremely hard to troubleshoot. Mike Ober. Show quote "Scott M." <s-mar@nospam.nospam> wrote in message news:%23CfroVvYGHA.3496@TK2MSFTNGP05.phx.gbl... > > Can someone explain the two terms "type-safe" and "thread-safe"? I > understand what a type and a thread are, but what does it mean for them to > be "safe"? > > >  |
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