this didn't seem to work in beta 12 (latest all in one installer)
----- Original Message ----- From: Henry Rich <[email protected]> To: [email protected] Sent: Tuesday, October 4, 2016 10:14 PM Subject: Re: [Jprogramming] Early assignment WAS: Non-mutable arrays Yes, this is executed in-place. In general, an assignment to a name whose value is not in use in another name causes that value to become eligible for in-place execution (with the possibility of early assignment) as long as the execution stack contains nothing beyond the value to be assigned. a=: ('b' ,~ 4,~])a =: 1 2 3 NB. in place (a=: ('b' ,~ 4,~])a =: 1 2 3) [ 1 NB. not in place Henry Rich On 10/4/2016 9:28 PM, 'Pascal Jasmin' via Programming wrote: > I made different suggestions in my beta post. namely, this expression should > also be optimized: > > > a=: ('b' ,~ 4,~])a =: 1 2 3 > > if possible, early assignment should also apply in scripts (even if through > tacit expressions). > > In general though, I think the advice "assign to new name to be safe", works > ok, but above line in console can be edited and reapplied with consistent > results. > > > > > > ----- Original Message ----- > From: Henry Rich <[email protected]> > To: [email protected] > Sent: Tuesday, October 4, 2016 7:25 PM > Subject: [Jprogramming] Early assignment WAS: Non-mutable arrays > > The whole point of operation in place is to avoid having to copy an > in-placeable argument; copying the argument would not be a good solution. > > After hearing the screams and dodging the dead cats, I have some proposals: > > 1. Early assignment (which is what we'll call the act of assigning an > intermediate value to a name that is about to be reassigned) will apply > only for sentences executed from an explicit definition. That will > eliminate the most likely source of confusion, which is erroneous > sentences typed into the console during debugging and exploration. > > For discussion here: > > 2. Early assignment could be disabled for sentences executed between > try. and catch. This would apply only to sentences from the same > execution that contains the try. Verbs called from within the try. > block will continue to have early assignment enabled as specified by the > setting of 9!:52''. > > 3. Error message text could be modified to indicate that an early > assignment occurred. I worry about this because existing code might > rely on the text of messages. > > Henry Rich > > > On 10/4/2016 3:01 PM, Louis de Forcrand wrote: >> I second Raul; the behaviour described is very counter-intuitive. Maybe add >> a third setting to 9!:53 which copies a at the start of a tacit verb >> involving in place operations? >> >> Also, what is the current (j804) behaviour when an in-place ammend fails? >> Since there's only one operation, if it fails a shouldn't be modified should >> it? >> If so, copying a at the beginning of a tacit verb containing more than one >> in-place operation (IPO) should always be faster than the current >> implementation, since copying would only be needed when two or more IPOs >> take place. >> >> Louis >> >>> On 04 Oct 2016, at 07:15, Raul Miller <[email protected]> wrote: >>> >>> When there are many verbs involved, it seems like the relative cost to >>> make a copy of the original at the start should be minor. >>> >>> Thanks, >>> >>> -- >>> Raul >>> >>> >>>> On Mon, Oct 3, 2016 at 10:52 PM, Henry Rich <[email protected]> wrote: >>>> The shape is just the tip of the iceberg. If the verb in question were m}, >>>> there would be no way to restore (a). >>>> >>>> And in general, many in-place verbs may have executed before the error. >>>> The >>>> original (a) may be long gone. >>>> >>>> If you foresee this as a problem, you should execute 9!:53(0) to turn off >>>> early assignment. >>>> >>>> Henry Rich >>>> >>>>> On 10/3/2016 10:34 PM, Raul Miller wrote: >>>>> >>>>> There are two reasons to be concerned about the value of a in the error >>>>> case. >>>>> >>>>> The minor one is error recovery. This is a simple example, and easy to >>>>> understand. What happens, though, when someone uses try./catch. with a >>>>> large code base? This issue would not be easy to isolate, nor will it >>>>> be easy to understand. >>>>> >>>>> A bigger issue is the one you mentioned here: debugging. When >>>>> debugging code which takes a long time to run, you will at times want >>>>> to fix the issue and continue, rather than burning the time necessary >>>>> to restart from the beginning. >>>>> >>>>> And, also, this seems like it will be hard to explain and at the same >>>>> time distract from issues which are more important. >>>>> >>>>> But keep in mind that I am not recommending the (a=:0)](a) mechanism >>>>> for this example. I made that suggestion for hypothetical cases. >>>>> >>>>> I am instead recommending that the shape of a be saved somewhere and >>>>> that a have its shape set to what it originally was, in the error >>>>> case. >>>>> >>>>> Is there some reason why you think that restoring a's shape in the >>>>> error case is not a viable approach here? >>>>> >>>>> Thanks, >>>> ---------------------------------------------------------------------- >>>> For information about J forums see http://www.jsoftware.com/forums.htm >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
