[Jprogramming] Possible to nest multiline noun definition within verb definition?

[Björn Helgason]

You can structure it any way you like



GetPrices1=: 4 : 0
sel =. ' cl_lname, cl_title, '
sel =. sel,'pp_year, pp_id, pr_mfd, pr_price'
from =. ' (price_profiles INNER JOIN'
from =. from,' prices ON pp_id = pr_pp) INNER JOIN'
from =. from,'(clients INNER JOIN revs ON cl_id = '
from =. from,'rv_client) ON pp_id = rv_pp'
where =.' cl_id=? AND rv_validuntil Is Null'
orderby =. ' cl_lname, pr_mfd;'
sqlcmd =. ' SELECT ',sel
sqlcmd =. sqlcmd,' FROM ',from
sqlcmd =. sqlcmd,' WHERE ',where
sqlcmd =. sqlcmd,' ORDER BY ',orderby
NB. profiles=. > _3 {."1 }. y query__db sqlcmd
NB. 'pp mfd prc'=: |: data
NB. profiles=. ((_1}.pp~:1|.pp),1) <;.2 profiles
)


SEL =: ' cl_lname, cl_title, '
SEL =: SEL,'pp_year, pp_id, pr_mfd, pr_price'
FROM =: ' (price_profiles INNER JOIN'
FROM =: FROM,' prices ON pp_id = pr_pp) INNER JOIN'
FROM =: FROM,'(clients INNER JOIN revs ON cl_id = '
FROM =: FROM,'rv_client) ON pp_id = rv_pp'
WHERE =: ' cl_id=? AND rv_validuntil Is Null'
ORDERBY =: ' cl_lname, pr_mfd;'

GetPrices2=: 4 : 0
('sel';'from';'where';'orderby') =.x
sqlcmd =. ' SELECT ',sel
sqlcmd =. sqlcmd,' FROM ',from
sqlcmd =. sqlcmd,' WHERE ',where
sqlcmd =. sqlcmd,' ORDER BY ',orderby
NB. profiles=. > _3 {."1 }. y query__db sqlcmd
NB. 'pp mfd prc'=: |: data
NB. profiles=. ((_1}.pp~:1|.pp),1) <;.2 profiles
)

   1 GetPrices1 3
 SELECT  cl_lname, cl_title, pp_year, pp_id, pr_mfd, pr_price FROM
(price...

   (SEL;FROM;WHERE;ORDERBY) GetPrices2 3
 SELECT  cl_lname, cl_title, pp_year, pp_id, pr_mfd, pr_price FROM
(price...



2007/2/14, Sherlock, Ric <R.G.Sherlock at massey.ac.nz>:
>
> Thanks for the dyad example and yes stored procedures might be a good
> idea but I'm using SQLite via Oleg's package and that doesn't support
> stored procedures. Bjorn, in my second (fuller) post on the subject I
> discounted appending to the line over multiple lines. I don't know about
> you but I find it tedious & messy (and much harder to copy/paste ;-) )
>
> I think the "keep it simple" advice I've had from a number of people is
> probably pretty sound, so will probably go that way for now.
>
> Being quite new to J I'm not really sure how important it is for the
> debugger to handle this sort of case (especially the anonymous), vs
> coming up with a way of allowing nesting. Would this be useful in more
> general cases, or would finding some way to allow nesting, render it a
> non-issue?
> To me, allowing nesting seems simpler and would result in more readable
> code, but I'm sure I'm not aware of all the issues.
>
> -----Original Message-----
> From: programming-bounces at jsoftware.com
> [mailto:programming-bounces at jsoftware.com] On Behalf Of Miller, Raul D
> Sent: Thursday, 15 February 2007 01:39
> To: Programming forum
> Subject: RE: [Jprogramming] Possible to nest
> multilinenoundefinitionwithinverb definition?
>
> Dan Bron wrote:
> > I would warn you away from this pattern if you use or intend to use
> > the J debugging facilities.  The dyad within the monad GetPrice is
> > anonymous, and consequently atomic from the J debugger's POV; hence
> > undebuggable.
>
> I consider this a defect in the debugger, and refuse to let it impact my
> code.
>
> Note that this defect also matters for code like:
>
> verba=:3 :0"1
>
> or
>
> verbb=:3 :0&.>
>
> etc.
>
> When I need to use that aspect of the debugger to isolate a problem with
> my code, I'm already in a position where I need to be re-writing my
> code.  And the debugger will tell me which specific function is having
> the problem.  So, in that case, I first rewrite the function to make the
> debugger happy with it, and then use the debugger to find the flaw, and
> then I fix the problem, test some more, and quite probably rewrite some
> more based on the outcome of my testing.
>
> But you're right that this issue does warrant an occasional warning.
>
> Finally note that for SQL, I prefer using stored procedures over inline
> code.  There are times when I can't (mysql doesn't support stored
> procedures), so sometimes I have to make allowences there, too.
>
> --
> Raul
>
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>



-- 
Björn Helgason, Verkfræðingur
Fugl&Fiskur ehf, Þerneyjarsund 23, Box 127
801 Grímsnes ,t-póst: gosinn at gmail.com
Skype: gosiminn, gsm: +3546985532
Landslags og skrúðgarðagerð, gröfuþjónusta
http://groups.google.com/group/J-Programming


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góður kennari getur stigið á tær án þess að glansinn fari af skónum
          /|_      .-----------------------------------.
         ,'  .\  /  | Með léttri lund verður        |
     ,--'    _,'   | Dagurinn í dag                     |
    /       /       | Enn betri en gærdagurinn  |
   (   -.  |        `-----------------------------------'
   |     ) |        (\_ _/)
  (`-.  '--.)       (='.'=)
   `. )----'        (")_(")