All right then. Good to know, thanks. > On Oct 19, 2016, at 4:50 PM, Thomas Bushnell, BSG <tbushn...@google.com> > wrote: > > On Wed, Oct 19, 2016 at 1:47 PM Pietro Gagliardi <andl...@lostsig.net > <mailto:andl...@lostsig.net>> wrote: > Manual memory management is a part of life in the C world. defer is the > solution that Go comes up with to situations where explicit cleanup is > necessary, and it's a powerful tool that I'm pretty sure *is* an innovation > Go did first. > > Oh my, no. It's a wonderful thing, but it's essentially equivalent to Lisp's > UNWIND-PROTECT or (in the outward case) Scheme's dynamic-wind. > > Thomas > > > > If you just follow the idiom > > cstr := C.CString(str) > defer C.free(unsafe.Pointer(cstr)) > > with nothing in between those two lines, then you won't have to worry about > whether something gets cleaned up every time, because the answer is yes, it > *will* get cleaned up every time! It's not like C anymore where you have to > worry about making sure every code path frees only what is allocated on that > code path, which means either juggling gotos or infinitely nesting ifs and > possibly NULL checks everywhere. > > Stop trying to fight the language; start using it. > > If you are really prone to forgetting to free something somewhere, write a > program using the go/... packages to do static analysis and evaluate the > lifetime of C objects for yourself. > >> On Oct 19, 2016, at 4:22 PM, andrew.sm...@miracl.com >> <mailto:andrew.sm...@miracl.com> wrote: >> >> I thought someone might ask! Im writing many wrapper functions to C >> functions that take multiple C.char* arguments. All of these require a call >> to C.free() before the wrapper function terminates. I can do this with defer >> but Im absolutely sure Im going to miss one or more of these out. So I was >> wondering, if I could get hold of the defer list, then I could encapsulate >> the construction together with the defer in a function. >> >> e.g. roughly : >> >> func NewCString(s string, deferList List) *C.char { >> cs := C.CString(s) >> deferList.PushBack(func() { C.free(cs) } >> return cs >> } >> >> Then in an *imagined world* I could write my wrapper simply as : >> >> func wrapper(s1 string, s2 string, s3 string) { >> deferList := runtime.DeferList() >> return C.inner(NewCString(s1,deferList), NewCString(s2,deferList), >> NewCString(s2,deferList)) >> } >> >> Basically, I cant seem to find a clean solution to ensure all these C.char* >> are 100% freed... swig allows me to wrap the C.char* with string, but swig >> is pretty awkward to use especially when wrapping the libraries I have. Im >> currently preferring cgo which seems much simpler and cleaner, but I dont >> have the equivalent of swigs typemaps to ensure all allocs are correctly >> freed... :o( >> >> >> >> On Wednesday, October 19, 2016 at 8:41:25 PM UTC+1, Pietro Gagliardi >> (andlabs) wrote: >> What do you want to do with it? >> >>> On Oct 19, 2016, at 3:31 PM, andrew...@miracl.com <> wrote: >>> >>> Hi, >>> >>> This is probably a long shot, but is it possible to get a reference to the >>> list of functions that the 'defer' statement populates? Is it exposed >>> and/or is it specific? >>> >>> Andy >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to golang-nuts...@googlegroups.com <>. >>> For more options, visit https://groups.google.com/d/optout >>> <https://groups.google.com/d/optout>. >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts+unsubscr...@googlegroups.com >> <mailto:golang-nuts+unsubscr...@googlegroups.com>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>.
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