C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  When is 'this' const?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Simon Elliott Guest Posted: Thu Oct 30, 2003 6:57 pm    Post subject: When is 'this' const? In a class function body, I'm trying to pass 'this' to another function. I'm getting an error because 'this' seems to have become const. Any ideas as to why this has happened? extern void DoSomethingWithFoo(foo* fooPtr); virtual void foo::doStuff(void) { DoSomethingWithFoo(this); // error: can't convert foo* const to foo* } Very weirdly, in another very similar class, exactly the same idiom has worked. The only difference is that the function is inlined into the header in the case which doesn't work. Is there some rule that says that 'this' is const when inlined into the header? -- Simon Elliott http://www.ctsn.co.uk/ Back to top Ron Natalie Guest Posted: Thu Oct 30, 2003 7:04 pm    Post subject: Re: When is 'this' const? "Simon Elliott" <simon (AT) nospam (DOT) demon.co.uk> wrote Quote: In a class function body, I'm trying to pass 'this' to another function. I'm getting an error because 'this' seems to have become const. Any ideas as to why this has happened? extern void DoSomethingWithFoo(foo* fooPtr); virtual void foo::doStuff(void) { DoSomethingWithFoo(this); // error: can't convert foo* const to foo* } By any chance is "doStuff()" really defined: virtual void foo::doStuff() const { ... Inside a const method, the this pointer is of type "const foo*." Back to top Simon Elliott Guest Posted: Thu Oct 30, 2003 7:10 pm    Post subject: Re: When is 'this' const? Simon Elliott <simon (AT) nospam (DOT) demon.co.uk> writes Quote: In a class function body, I'm trying to pass 'this' to another function. I'm getting an error because 'this' seems to have become const. Any ideas as to why this has happened? extern void DoSomethingWithFoo(foo* fooPtr); virtual void foo::doStuff(void) { DoSomethingWithFoo(this); // error: can't convert foo* const to foo* } Very weirdly, in another very similar class, exactly the same idiom has worked. The only difference is that the function is inlined into the header in the case which doesn't work. Is there some rule that says that 'this' is const when inlined into the header? I've now discovered that this issue was due to a silly mistake I made further down the inheritance chain. I may have misunderstood the error message as it said "foo* const" which I read as "const foo*"... -- Simon Elliott http://www.ctsn.co.uk/ Back to top Micah Cowan Guest Posted: Fri Oct 31, 2003 8:53 am    Post subject: Re: When is 'this' const? "Ron Natalie" <ron (AT) sensor (DOT) com> writes: Quote: "Simon Elliott" <simon (AT) nospam (DOT) demon.co.uk> wrote In a class function body, I'm trying to pass 'this' to another function. I'm getting an error because 'this' seems to have become const. Any ideas as to why this has happened? extern void DoSomethingWithFoo(foo* fooPtr); virtual void foo::doStuff(void) { DoSomethingWithFoo(this); // error: can't convert foo* const to foo* } By any chance is "doStuff()" really defined: virtual void foo::doStuff() const { ... Inside a const method, the this pointer is of type "const foo*." But the error message indicates that this is of type "foo * const". Weird. -- Micah J. Cowan [email]micah (AT) cowan (DOT) name[/email] Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.