On 16.06.2024 02:02, Rick McGuire wrote:
Um,
a = .stream~new(filename)~arrayin
is a one liner that reads into an array.
Yes, that is the beauty of cascading messages! However, the file needs to be closed (e.g. if one
wishes to replace it later) which is not possible in the same line, rather another statement needs
to be issued to close the stream, actually for closing the stream one needs a variable to store the
stream temporarily, hence two more statements:
s=.stream~new(filename)
a=s~arrayin
s~close
... some other code in between ...
.stream~new(filename)~~open("replace")~~arrayout(a)~close
With the suggested class methods it would become possible to do instead:
a=.stream~arrayin(filename)
... some other code in between ...
.stream~arrayout(filename,a)
which is much simpler, shorter, hence easier to code, easier to comprehend and as a result less
error prone.
---rony
On Sat, Jun 15, 2024 at 7:50 PM Gilbert Barmwater <gi...@bellsouth.net> wrote:
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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