Question:
Will There be a 4D release soon to increase the usage of returned values on 4D
command, so that I can reduce the reliance on system global process variables,
like “OK"?
a good 4D command canidate is Receive Packet.
I consider "OK" global variable because it never looses scope, which is what a
global variable is.
If this is not the Right forum for this question, then the answer to this
question might be where do I make that request.
Why returned values are a benefit: (optional
reading)-------------------------------------------------------------
I don’t want to get into a discussion why global variables should not be used.
There are very legitimate reasons for wanting enhancements of 4D commands to
return a values
Back to Receive Packet. and why its specifically is a benefit
Receive Packet($docref;$data;$EOL) for example sets the OK system global
process variable to 1, unless it reads no data ,then it is sets it to 0
It should be expanded, to return 1 or 0, and for backward compatibility the OK
could be maintained as is.
Therefor I could write less code lines similar to c#, java, javascript, c++,
etc. (pseudo example below)
while( (line = file.readline()) ==1)
//do stuff
End while
Currently, because Receive Packet does not return a value, I instead need to
write code like this in 4D.
Receive Packet($docref;$data;$EOL) //read the first line
if (ok=1)
repeat
//do stuff
Receive Packet($docref;$data;$EOL)
until (ok=0)
(OR)
repeat
Receive Packet($docref;$data;$EOL) //read, this example not as good because if
in do stuff changes OK and I don’t program around it, the until will break
if (ok=1)
//do stuff
end if
until (ok=0)
I realize I could write my own read line method(which I have), but I just
thought it would be handy if Receive Packet itself could return 1 or 0, in a
future code release.
It would also be nice if the read line supported CR, CRLF, LF types… I got
around this by writing my own open file routine, which gets the EOL (this code
is not shown)
Example of Readline:
While (Readline ($docref;->$read;$EOL)=1) //Parse the text file referenced ,
returns 1 if not end of File, 0 at end; read is the contents of line; EOL must
be provided
//do stuff
End while
// Method: readline
C_LONGINT($0) //returns 1 or 0
C_TIME($1) //doc reference
C_POINTER($2) //data can be updated and returned to user
C_TEXT($3) //EOL
//variables
C_TEXT($READ)
//read to EOL character
RECEIVE PACKET($1;$READ;$3)
$2->:=$read
If (Length($read)>0)
$0:=1 //sometimes the last line does not have a EOL, so we still need to
return 1
Else
$0:=ok
End if
thanks,
Aaron
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