rexxref says that for DO OVER Collection, a MAKEARRAY method is required,
but that's not the full story: Rexx uses the REQUEST("ARRAY") mechanism to
do the conversion, which will send a MAKEARRAY message, and if no such
method exists, will fail (as documented) without testing for an UNKNOWN
method.
Whether this is in fact working as designed (but should probably be better
documented) I'm not sure.
On Sun, Nov 6, 2016 at 3:34 PM, Rony G. Flatscher <rony.flatsc...@wu.ac.at>
wrote:
> The DO...OVER statement allows one to iterate over a collection. To do so
> a MAKEARRAY is requested and the resulting array is then iterated over.
>
> It seems, that the code in DO...OVER does not send the MAKEARRAY message,
> if it does not find that method in the receiver object, irrespectible
> whether an UNKNOWN method is available that may step in and return that
> array upon request.
>
> Here is a Rexx program demonstrating this problem, bug:
>
> t=.test~new
> tArr=t~makearray~toString(,"/")
> say "tArr:" tArr
>
> do o over t
> say o
> end
> say "---"
>
> u=.uuu~new
> uArr=u~makearray~toString(,"/")
> say "uArr:" uArr
> do o over u
> say o
> end
> say "---"
>
> *::class test
> ::method makearray*
> return ("one", "two", "three")
> *::class uuu**::method unknown*
> use arg methName, methArgs
> * if methName="MAKEARRAY" then return ("one", "two", "three")*
>
> say "in" self"::unknown, about to raise a syntax condition"
> raise syntax 98.913 array (self)
>
>
> The class "TEST" implements the MAKEARRAY method and the DO...OVER
> succeeds.
>
> The class "UUU" does not implement the MAKEARRAY method, but an UNKNOWN
> method that returns an array, if a MAKEARRAY message was received. Here,
> DO...OVER causes a 98.913 syntax error, which aborts the program!
>
> Here is the output of running the above program:
>
> F:\test\oorexx\makearray>test1
> tArr: one/two/three
> one
> two
> three
> ---
> uArr: one/two/three
> 13 *-* do o over u
> Error 98 running F:\test\oorexx\makearray\test1.rex line 13: Execution error.
> Error 98.913: Unable to convert object "an UUU" to a single-dimensional
> array value.
>
> It may be the case that the interpreter tries to optimize by checking for
> the existence of a MAKEARRAY method in the receiving object and if not
> found short-circuiting by raising the syntax error. Instead it should let
> the UNKNOWN mechanism to get exercised, such that it becomes possible to
> delegate the execution of such unknown messages (like MAKEARRAY in the
> class UUU above) by other code, which is the purpose of the UNKNOWN
> mechanism in the first place.
>
> This is with ooRexx 5.0.0 beta, not sure about previous versions.
>
> If there are no counter arguments, then I will file a bug report for this
> in the tracker.
>
> ---rony
>
> P.S.: "DO WITH index i and item o" works by supplying the SUPPLIER method
> explicitly or implicitly by the UNKNOWN method. Here is an example for that
> variant:
>
> t=.test~new
> say "tArr:" tArr
>
> do with index idx item o over t
> say "index:" idx "item:" o
> end
> say "---"
>
> u=.uuu~new
> say "uArr:" uArr
> do with index idx item o over u
> say "index:" idx "item:" o
> end
> say "---"
>
> *::class test**::method supplier*
> return .supplier~new((1,2,3), ("one", "two", "three"))
> *::class uuu**::method unknown*
> use arg methName, methArgs
> * if methName="SUPPLIER" then return .supplier~new((1,2,3), ("one", "two",
> "three"))*
>
> say "in" self"::unknown, about to raise a syntax condition"
> raise syntax 98.913 array (self)
>
> Output (no runtime error):
>
> F:\test\oorexx\makearray>test2
> tArr: TARR
> index: one item: 1
> index: two item: 2
> index: three item: 3
> ---
> uArr: UARR
> index: one item: 1
> index: two item: 2
> index: three item: 3
> ---
>
>
>
>
>
>
>
>
>
>
>
> ------------------------------------------------------------
> ------------------
> Developer Access Program for Intel Xeon Phi Processors
> Access to Intel Xeon Phi processor-based developer platforms.
> With one year of Intel Parallel Studio XE.
> Training and support from Colfax.
> Order your platform today. http://sdm.link/xeonphi
> _______________________________________________
> Oorexx-devel mailing list
> Oorexx-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/oorexx-devel
>
>
------------------------------------------------------------------------------
Developer Access Program for Intel Xeon Phi Processors
Access to Intel Xeon Phi processor-based developer platforms.
With one year of Intel Parallel Studio XE.
Training and support from Colfax.
Order your platform today. http://sdm.link/xeonphi
_______________________________________________
Oorexx-devel mailing list
Oorexx-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/oorexx-devel
