[Gambas-user] Read and Write Null

Benoît Minisini gambas at ...1...
Sun Jul 24 11:46:31 CEST 2011

> good morning Benoit,
> this issue has kept me awake almost all the night.
> if i have an uninitialized collection and want it to be written to and
> then read from a file:
> Dim cCol As Collection = Null
> Dim hFile As File
> hFile = Open "~/test" For Write Create
> Write #hFile, cCol As Variant
> Close #hFile
> hFile = Open "~/test" For Read
> cCol = Read #hFile As Variant
> Print cCol
> i get segfault (in Write instruction) and figured out that it is about
> this line (in my rev #3944 gbx_stream.c:1116)
> if (TYPE_is_object(type)) type = T_OBJECT;
> and the switch branch for T_OBJECT which doesn't seem to expect a Null
> object (i think... i didn't look very closely to it)
> (why am i telling you this, you'll know it better)
> so i sat down and manually created my file without Writing Null as a
> datatype but as a string:
> Write #hFile, "\x0f\x00", 2
> and thought that it will at least now succeed but i get an error about
> typemismatch (wanted standard type got Null instead). Read also seems
> not to expect the Null (there is no T_NULL branch in STREAM_read_type's
> switch)
> shouldn't it be possible to at least read that Null as it is a standard
> type?
> regards,
> tobi


The bug should be fixed in revision #3946.


Benoît Minisini

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