First let me offer the following way to write the contents of an array
to a stream that only requires a single line:
.stream~new(streamFileName)~~arrayOut(arr [,Lines|Chars])~close
Unfortunately, there is no corresponding "one-liner" for reading the
contents of a stream into an array. This lack of "symmetry" has always
bothered me and I have experimented over the years with possible
solutions. Not too long ago I was able to devise a way to finally
accomplish it.
Before I reveal it, let me note that the above comments are equally
applicable to charOut/charIn and lineOut/lineIn should one wish to deal
with character(s) or a single line of output/input.
My solution is to add additional instance methods to the .stream class
named arrayInto, charInto and lineInto. The difference between them and
the similar *In methods is that the first argument is a variable
reference followed by the "standard" *In arguments. These methods
perform the operation of the related *In method and then assign the data
- array, character(s) or line - to the value of the variable reference.
So the corresponding "one-liner" for reading the contents of a stream
into an array is:
.stream~new(streamFileName)~~arrayInto(>arr, [Lines|Chars] )~close
But, you might say, ooRexx doesn't allow you to "add" methods to the
pre-defined classes like .stream. That is not strictly true and there
are several ways around that. I had planned to talk about that as part
of a planned presentation at the Vienna Symposium next May but, since
the subject has come up now, it looks like I will need to reveal it
ahead of time.
On a more general, philosophical note, I prefer to find solutions that
do NOT require adding classes, methods, or functions to the base ooRexx
but that can be included with a ::requires statement, similar to the way
that, e.g. RxMath functions are handled. I guess that goes back to the
original Rexx idea of keeping the language small but is also consistent
with how other languages provide "libraries" of added functionality.
If anyone is interested in the implementation of the arryInto method, I
will post it here and, if not, will discuss it during the Symposium.
Gil
On 6/15/2024 2:38 PM, Rony G. Flatscher wrote:
The Stream class has the handy instance methods arrayIn and arrayOut.
To read the content of a stream into an array the following statements
are necessary:
s=.stream~new(streamFileName)
s~open( [read|both] )
arr=s~arrayIn( [Lines|Chars] )
s~close
To write the content of an array into a stream the following
statements are necessary:
s=.stream~new(streamFileName)
s~open( [write | both [append|replace]] )
s~arrayOut(arr [,Lines|Chars])
s~close
---
It would be very handy, if the Stream class also offered as class
methods arrayIn and arrayOut that would allow one single statement to
read from any stream (file) into an array or to write an array to any
stream (file).
class method arrayIn:
arr=.stream~arrayIn( streamFileName [,Lines|Chars] ) -- default: Lines
and
class method arrayOut:
.stream~arrayOut(streamFileName , arr [,append|replace] [,Lines|Chars] )
-- default: append, Lines
What do you think?
Would you see any problems and if so which ones?
---rony
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Gil Barmwater
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