* Re: What good is ``?
@ 1991-07-01 22:44 Paul Haahr
0 siblings, 0 replies; 2+ messages in thread
From: Paul Haahr @ 1991-07-01 22:44 UTC (permalink / raw)
To: mjd, rc
i guess i should respond to this, since i pressured byron into adding ``
many moons ago. my argument is you need either ` and ifs, or `` and
`` is simpler. my best of all possible worlds solution gets rid of
ifs, because i don't like state variables. with ifs, how do you use
two different backquote expressions in the same command? (answer:
you can't.)
incidentally, none of these
x=`{ ifs=: echo -n a:b }
x=` ifs=: { echo -n a:b }
ifs=: { x=`{ echo -n a:b } }
is the same as
x=`` : { echo -n a:b }
although this is:
ifs=: { x=`{ echo -n a:b } ; }
moreover, it is impossible to define a shell function to do `` because
brace enclosed groups are not first class objects in rc. (that is my
most serious gripe against the language.)
`` may very well be a mistake. certainly it and ifs are redundant. i
believe byron's implementation translates
`foo
to
`` $ifs foo
internally, and vice-versa for whatis, so the cost seems minimal to me.
it depends on which one you treat as extra. (that ifs is in td's paper
probably makes that a closed issue, unfortunately for my case.)
so what do other people say? is `` too much of a blemish?
paul
[ it is surprising to me that i find myself being the main proponent of
creeping featurism. i'm usually a vociferous opponent. i guess that's
what happens when you become a user instead of a designer. ]
^ permalink raw reply [flat|nested] 2+ messages in thread
* What good is ``?
@ 1991-07-01 21:08 Mark-Jason Dominus
0 siblings, 0 replies; 2+ messages in thread
From: Mark-Jason Dominus @ 1991-07-01 21:08 UTC (permalink / raw)
To: rc; +Cc: mjd
On a related note: Given Byron's policy of not adding features unless
the feature implements genuinely new functionality, what's the rationale
behind ``?
Why not replace
`` (foo) {bar}
with
`{ ifs=(foo) echo `{bar}}
which is the obvious way to do the same thing without a crufty
piece of syntax?
People who like `` anyway can make a shell function.
The night is pleasing to us because, like memory, it erases idle details.
Mark-Jason Dominus mjd@central.cis.upenn.edu
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