Hi all,
Right now we have an 'stdio' variable and various words which operate
on it,
: read stdio get stream-read ;
: readln stdio get stream-readln ;
: write stdio get stream-write ;
: print stdio get stream-print ;
with-stream rebinds it and closes it after, with-stream* rebinds it
without closing.
This makes for very nice and concise code, but there's one problem
with it and that it cannot express the case where you want to read
from one file and write to another at the same time. Instead, you need
to do something like this,
"in.txt" utf8 <file-reader> [
"out.txt" latin1 <file-writer> [
<duplex-stream> [
...
] with-stream*
] with-disposal
] with-disposal
Or if you want to read from a file and print to the console in the
same code,
stdio get
"in.txt" utf8 <file-reader> [
swap <duplex-stream> [
...
] with-stream*
] with-disposal
This is too awkward for a language named "Factor".
I propose replacing the stdio variable with two variables, input and
output. The with-stream combinator would still exist, and it would
bind both, but there will be two new combinators, with-input and with-
output. These will rebind just one of the two variables.
The stream words would change too: reader words like read, read1,
would operate on input, and writer words like write and print would
operate on output.
Note that these changes are pretty much backwards-compatible. Code
using with-stream continues to work and very rarely does code access
the stdio variable directly.
A more radical idea is to remove duplex streams altogether. Instead,
words like <process-stream> and <client> would return a pair of
streams, a reader and a writer. A with-streams combinator with stack
effect ( in out quot -- ) could be used here.
Slava
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