#661 Allow "do over .nil"

[Erich]

When a method or a function that normally returns a collection object, returns .nil as an exceptional case, it would often come handy if
do item over .nil
worked as an empty loop.
(I assume that's equivalent to asking .nil~makeArray to return a zero-size array)

[Moritz Hoffmann]

Hi Erich,
I do not understand what you want to achieve with this. Do you want to bind the variable item to the value .nil for one iteration or do you want to the loop to do nothing at all? The first case can be achieved by iterating over a supplier that just supplies a single value, .nil. The latter would not make much sense either I think.
Best,
Moritz

[Rick McGuire]

I suspect Erich's desire is .nil will go for zero iterations. This covers the case where a method return value is either an array of items or .nil if there are no items available.

[Erich]

I suspect Erich's desire is .nil will go for zero iterations

Yes, that's what I meant.

Here's an example. It would be nice (and more REXX-ish?) if you could code:

files = .File~new(directory)~listFiles
do file over files
  ..
end

without having to protect the do .. loop with:

if files \== .nil then ..

Above RFE was only one of the have-to-check-nil situations, I sometimes run
into. Another one might be:

file = .File~new(..)
earliestDate = .DateTime~new~addDays(-30)
date = file~lastModified
if date < earliestDate then ..

Again, you have to protect the "if" with "if date \== .nil .:"

On Thu, Apr 23, 2015 at 3:32 PM, Rick McGuire bigrixx@users.sf.net wrote:

I suspect Erich's desire is .nil will go for zero iterations. This covers
the case where a method return value is either an array of items or .nil if
there are no items available.

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• [feature-requests:#661]
  http://sourceforge.net/p/oorexx/feature-requests/661 Allow "do over .nil"*

Status: pending
Milestone: None
Created: Wed Mar 18, 2015 10:27 AM UTC by Erich
Last Updated: Thu Apr 23, 2015 01:29 PM UTC
Owner: nobody

When a method or a function that normally returns a collection object,
returns .nil as an exceptional case, it would often come handy if
do item over .nil
worked as an empty loop.
(I assume that's equivalent to asking .nil~makeArray to return a zero-size
array)

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