Re: [screen-devel] PATCH: new 'if' primitive

[Micah Cowan]

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Steve Kemp wrote:
> On Tue Oct 21, 2008 at 13:18:41 -0700, Micah Cowan wrote:
> 
>> There's plenty of time to discuss it, given that it definitely wouldn't
>> be added for 4.1.0. If Lua support is mature by then, then the obvious
>> solution would be to just use that, instead of inventing something new.
> 
>   That sounds reasonable.   Optimistically I was hoping for a new
>  branch, or similar, which could try out some of these changes.
>  As things stand I guess I'm going to have to keep maintaining my
>  own set of changes which is not ideal, but something I can live
>  with.

No, I'll set something up for this soon.

>   You're definitely right that with lua support a lot of the things
>  I've been doing would be better implemented in it.  But I'm assuming
>  that like any changes I've suggested any lua integration into
>  mainline Screen is going to be in the future.

Right. Definitely not 4.1.0. Maybe 4.2.0, maybe later.

>> Other than that, I'd say that in general it'd be good to emulate shell
>> semantics, both for test-like comparisons and for subshells. Not
>> necessarily full-featured support, but those features we choose to
>> supply should probably mimic Bourne/POSIX syntax.
> 
>   I think that I've managed to do that now:
> 
>     if -x file/path ..
>     if -d file/path ..
>     if -e file/path ..
> 
>     if $FOO -eq "bar" ..

In usual shell that would be =, not -eq (-eq is for numbers; the reverse
of Perl).

>     if `hostname` -eq steve ..
>     if `"hostname --fqdn"` -ne "bar" ..
>     if "test one" -eq "test two" "echo 'cats and dogs living together'"

It'd also be nifty to support $(...) as well. But that's not crucial.

Also, I'm guessing we're not going to do string interpolation; that is,
unlike shell,

  if $FOO = "foo bar"

(note the space) might actually be sensible.

- --
Micah J. Cowan
Programmer, musician, typesetting enthusiast, gamer.
GNU Maintainer: wget, screen, teseq
http://micah.cowan.name/
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