From: John Cowan <xxxxxx@ccil.org>

Date: Saturday, May 30, 2020 10:43 PM

Thanks! (I had understood that you weren't going to work on the Chibi implementation any more; was that wrong?)

As you noted, the now removed absolute-path "can be implemented in completely portable Scheme if given two arguments, an absolute path and a second path (relative or absolute)," there was no great value add to me implementing it, ditto my abandoning call-with-temporary-filename long ago.

That's not true for with-cooked-mode, but further illustrating my point about how all these with- and without- procedures belong in the same SRFI, that's because it's a lot of work to get one's head into this messy domain, and to do another tedious example of much the same thing.  I don't consider it to be truly essential as long as you cite the correct stty flags as was done with the other procedures.

Reverting code because you realized a fatal flaw with an otherwise cunning plan?  Not much work at all.  And I'm a bit more kindly disposed towards the implementation now that I'm using it for real in my backup program, and cleanly, straight out of the SRFI repository now that I've made it standalone.

[ Environment variable questions I can't answer. ]

- Harold

On Sat, May 30, 2020 at 2:42 PM <xxxxxx@ancell-ent.com> wrote:

Note, the Chibi-Scheme sample implementation will not be changed/reverted until the dust settles on these editorial changes.

From: John Cowan <xxxxxx@ccil.org>

Date: Saturday, May 30, 2020 12:20 PM

 I've pushed a new version that will become draft 8 when the three issues mentioned below are cleared up.  You can read it at <http://htmlpreview.github.io/?https://raw.githubusercontent.com/johnwcowan/srfi-170/master/srfi-170.html>. Most of the changes are editorial, but these are not:

1) Umask and current directory reverted.

[...]

The division of labor I'd prefer is that you handle the HTML going forward, so here just revert the language that the Chibi Scheme sample implementation does these as procedures, not parameters, and I'll revert the code.

2) Absolute path removed.

[...]

Ditto the warning it's not implemented in the Chibi Scheme sample implementation.

[ with-cooked-mode ]

Here are the outstanding issues:

a) Should section 3.11, setting the environment, be removed?

As long as your code is pure Scheme, you can capture an environment variable in a parameter and then bind the parameter.  The problems arise when your program contains code in C (or some other language) that depends on the correct setting of the environment variable.

One known example is the glibc timezone facilities: if your program wants to use a particular timezone other than local and UTC, it has to use putenv to change the value of TZ.  On the other hand, the Posix time API *sucks*, which is why I have a pre-SRFI for that too.

Any other Real World examples?

If someone has a need to use that Posix time API....

These are quite simple to wrap, in Chibi Scheme's autogenerating FFI:

(define-c errno (%setenv setenv) (string string int))

(define-c errno (%unsetenv unsetenv) (string))

And while I can't remember the reason now, I do remember thinking I'll be needing them in the cloud backup program I'm writing right now....  Maybe for spawning helper programs?  It was something cross process I think.  Which of course is eventually in the remit of the POSIX process SRFI, but for now I assume Schemes other than Chibi Scheme also have basic implementations of that, whereas Chibi Scheme surprisingly lacks unsetenv.

b) Should with-*-mode be removed?

These are low-level and messy.  I have a pre-SRFI for TUIs,  and there is termbox, which is trivial to wrap.

c) Should without-echo be removed?

The argument is the same as for with-*-mode, but less cogent, and my sense is that this facility is more useful.  Perhaps it should be packaged at a higher level, though, like (get-password prompt), where prompt is a string.

Whatever has without-echo absolutely should have the with-*-mode procedures, all of them get equally low-level, and all are messy.  The latter are a bit more work because they have to do things to an input port as well as an output port, plus it depends on your FFI.  E.g., there's an array inside the termios struct, albeit not needed for without-echo, which Chibi Scheme's otherwise very nifty autogenerating FFI can't access.  I ended up hand coding all the C functions, but it's mostly cut, paste, and alter work of quite simple getters and setters.

- Harold