[Gretl-devel] Re: bug with "const" in function
Am 02.02.2024 um 15:12 schrieb Allin Cottrell: Right, but that happens automatically within any given gretl process, regardless of whether any series, or list of series, is passed to the called function. As a trivial illustration: In the MPI context the dataset (if present) is not automatically passed between distinct gretl processes, but this is ensured by the --send-data option for a mpi block. Another trivial illustration: Aha! That's very interesting, I wasn't aware of it, because I thought it would go against the idea of function encapsulation. But very useful here, so I don't need any workaround, it seems. There's one gotcha to note here. If you don't need to pass the entire dataset in the MPI context you can use --send-data=L, where L is a list of series, BUT this won't work if L contains just const. That's because inter-process transfer of data is done using a gdt or gdtb file, and "const" is not explicitly represented in such a file. Trying to save a gdt[b] file containing no series other than const will fail with the message "No data to save!". It's fine if L contains just a single series, but it can't be series 0. That's OK. You could insert "list L = index" before the mpi block above, and make the option --send-data=L. I guess a "genr index" would also be needed, because not every existing dataset has the index series. But it's not really needed anyway. Anyway, the behavior you found with exists() is clearly wrong, and I'm satisfied that a proper fix can be engineered: we'll give the called function a copy of const under the parameter name rather then doing the "shift and rename" thing. That should be in git quite soon. OK, good. sven ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: bug with "const" in function
On Fri, 2 Feb 2024, Sven Schreiber wrote: Am 02.02.2024 um 01:42 schrieb Allin Cottrell: However, that treatment of the "const" modifier cannot work when the series passed is the one named "const" (with ID number 0). That series is supposed to be automatically available at all levels of function execution, Well, but only if the dataset context is passed on to the called function, right? Right, but that happens automatically within any given gretl process, regardless of whether any series, or list of series, is passed to the called function. As a trivial illustration: function void f (void) print const smpl end function nulldata 8 setobs 4 2016:1 f() In the MPI context the dataset (if present) is not automatically passed between distinct gretl processes, but this is ensured by the --send-data option for a mpi block. Another trivial illustration: function void f (void) printf "process %d\n", $mpirank print const smpl end function nulldata 8 setobs 4 2016:1 mpi --send-functions --send-data f() end mpi --np=2 There's one gotcha to note here. If you don't need to pass the entire dataset in the MPI context you can use --send-data=L, where L is a list of series, BUT this won't work if L contains just const. That's because inter-process transfer of data is done using a gdt or gdtb file, and "const" is not explicitly represented in such a file. Trying to save a gdt[b] file containing no series other than const will fail with the message "No data to save!". It's fine if L contains just a single series, but it can't be series 0. You could insert "list L = index" before the mpi block above, and make the option --send-data=L. Anyway, the behavior you found with exists() is clearly wrong, and I'm satisfied that a proper fix can be engineered: we'll give the called function a copy of const under the parameter name rather then doing the "shift and rename" thing. That should be in git quite soon. Allin ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: bug with "const" in function
Am 02.02.2024 um 01:42 schrieb Allin Cottrell: However, that treatment of the "const" modifier cannot work when the series passed is the one named "const" (with ID number 0). That series is supposed to be automatically available at all levels of function execution, Well, but only if the dataset context is passed on to the called function, right? Otherwise no series is available inside, not even "const" (ID 0). This is the background of what I'm trying to achieve, with a little bit of borderline hacking. I'm working with MPI and (sometimes, not always in my general meta function) need to pass on the dataset context. And I thought the safest way is to use the series that always exists, namely "const". This issue hasn't been reported before, which is not surprising since passing series 0 as an argument is in general pointless, since it's already available everywhere and is of no interest other than as the intercept in a regression. I think I see a way of making it harmless but I need to do some more testing before I'm sure. Thanks. Again, the interest here is not the "const" series per se, but the idea is to "piggyback" the dataset context on an arbitrarily chosen series. But I think I can work around this particular problem; for example, two hackish pieces of syntax that work instead of the passed arg "const" are: 1) "(dataset)[1]" - assumes at least one other series, which is OK; not that "dataset[1]" didn't work 2) "deflist(const)[1]" - uglier, but also works (More background explanation: I first tried to use a gretl list that is of more direct interest, but the problem was that this doesn't work in the also covered case that no dataset is present. That is, I can use the function arg specification 'series s[null]' and the null default also works without an active dataset, but 'list L[null]' yields an error then. I know this is because of the special behavior of lists, which always exist even when "null-ed" or omitted. But that's causing a problem here, hence my workaround with "const".) If it's too dangerous to accommodate the passing of just "const" (and since usually there isn't much point in it), perhaps it's better to just ban it? Or perhaps ban the combination of passing "const" to a function that uses the const modifier for its arg? thanks sven ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: bug with "const" in function
On Thu, 1 Feb 2024, Sven Schreiber wrote: this is a bug that is probably triggered only in unusual circumstances, but it happened to me in a kind-of real world function development scenario: function void serc (const series s) # the 'const' here is important if exists(s) print "to be" else eval typename(s) print "or not to be" endif end function open denmark print "call 1" serc(LRM) print "call 2" serc(const) # "const" is a series ID 0 in all datasets # -> produces "null" and "or not to be", as if "s" inside # the function didn't exist This behavior has been there "forever" (or more precisely, ever since the "const" modifier for hansl function arguments has been supported). It's quite an interesting problem. When a series is given as a function argument without the "const" modifier, gretl gives the function a copy of the incoming series, under the name given by the function parameter. But when the "const" flag is given, the series in question is shifted from the function-execution level of the caller to that of the callee, and is renamed using the parameter name -- and then these changes are reverted when the function exits. However, that treatment of the "const" modifier cannot work when the series passed is the one named "const" (with ID number 0). That series is supposed to be automatically available at all levels of function execution, and renaming it would make in unavailable under its proper name inside the function -- a real bug. This issue hasn't been reported before, which is not surprising since passing series 0 as an argument is in general pointless, since it's already available everywhere and is of no interest other than as the intercept in a regression. I think I see a way of making it harmless but I need to do some more testing before I'm sure. Allin___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
