Add a wrapper for C.H5Lexists for the CommonFG, returns nil if link e…

[zyc-sudo]

Added the C.H5Lexists to check if the link(group, dataset, link) exists
Please take a look.

[zyc-sudo]

This GolangCI failure:
compilation terminated.
# gonum.org/v1/hdf5
./cgoflags.go:12:19: fatal error: hdf5.h: No such file or directory

I assume it is a CI setup error rather than code error?
// #include "hdf5.h"

[kortschak]

That failure looks to be related to golangci/golangci#35. I'm not sure how to deal with this since we are completely tied to Cgo with this repo.

[kortschak]

This should be fixed by #60.

[zyc-sudo]

Great! Looking forward to contributing!

…

On Tue, Sep 17, 2019 at 6:36 PM Dan Kortschak ***@***.***> wrote: This should be fixed by #60 <#60>. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#57?email_source=notifications&email_token=AEOWLFTFAOITRDH5FCKBSLLQKFLWXA5CNFSM4IXQ5BMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD66DPWQ#issuecomment-532428762>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEOWLFUUURFDQFFOQRGQZUTQKFLWXANCNFSM4IXQ5BMA> .

[kortschak]

I think a bool is better here. Possibly with an error as well, but probably not.

[zyc-sudo]

Sure will do tomorrow

…

On Tue, Sep 17, 2019 at 10:31 PM Dan Kortschak ***@***.***> wrote: ***@***.**** commented on this pull request. I think a bool is better here. Possibly with an error as well, but probably not. ------------------------------ In h5g_group.go <#57 (comment)>: > @@ -162,3 +163,15 @@ func (g *Group) CreateTableFrom(name string, dtype interface{}, chunkSize, compr func (g *Group) OpenTable(name string) (*Table, error) { return openTable(g.id, name) } + +// CheckLink checks if a link( can be group or dataset or actual link )exsit or not. This method won't give you annoying hdf5 warnings when called in a goroutine +// CheckLink returns nil when a link exist, return an error when the link doesn't exist or some other error occured // LinkExists returns whether a link with the specified name exists in the group. func (g *CommonFG) LinkExists(name string) bool { c_name := C.CString(name) defer C.free(unsafe.Pointer(c_name)) return C.H5Lexists(g.id, c_name, 0) > 0 } The HDF5 API is discusting for this. The return status, according to this <https://support.hdfgroup.org/HDF5/doc/RM/RM_H5L.html#Link-Exists>, is almost entirely uninformative for the failing case, so I'm not sure that it's even worth bothering to indicate the error return. @sbinet <https://github.com/sbinet>? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#57?email_source=notifications&email_token=AEOWLFSWSXQ3MBC25HEBJO3QKGHJPA5CNFSM4IXQ5BMKYY3PNVWWK3TUL52HS4DFWFIHK3DMKJSXC5LFON2FEZLWNFSXPKTDN5WW2ZLOORPWSZGOCFBZEOI#pullrequestreview-289641017>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEOWLFTEIBWD65EL45YZJGTQKGHJPANCNFSM4IXQ5BMA> .

[zyc-sudo]

@kortschak Hi I make the changes, I also merged it to the other PR regarding the images where this feature is used

[zyc-sudo]

Just pushed all the requested changes

…

On Thu, 19 Sep 2019 at 19:22, Dan Kortschak ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In h5g_group_test.go <#57 (comment)>: > @@ -28,6 +32,14 @@ func TestGroup(t *testing.T) { t.Errorf("wrong Name for group: want %q, got %q", "/foo", g1.Name()) } + if !f.LinkExists("/foo") { + t.Fatalf("err: %s", "/foo should exist at this time") Yes. Thanks. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#57?email_source=notifications&email_token=AEOWLFQ7ZYL6RLOAMZ5V2HLQKQCT5A5CNFSM4IXQ5BMKYY3PNVWWK3TUL52HS4DFWFIHK3DMKJSXC5LFON2FEZLWNFSXPKTDN5WW2ZLOORPWSZGOCFLKMCI#discussion_r326420781>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEOWLFSLKOG56SW2ZBS3DZ3QKQCT5ANCNFSM4IXQ5BMA> .

[kortschak]

Thanks

[zyc-sudo]

Thanks a lot! This is the first time I participated github open source. Thank you very much for your patience

…

On Thu, Sep 19, 2019 at 9:08 PM Dan Kortschak ***@***.***> wrote: Thanks — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#57?email_source=notifications&email_token=AEOWLFWC2CBHHKMN477DVEDQKQPCPA5CNFSM4IXQ5BMKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD7FHWRI#issuecomment-533363525>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEOWLFWFMOYILKD4UJUDAGTQKQPCPANCNFSM4IXQ5BMA> .

[kortschak]

I neglected to say, would you please send a PR adding yourself to AUTHORS and CONTRIBUTORS at gonum/gonum. Please use the commit message "A+C: add Yucheng Zhu" (I assume this is your name from the commits).