Environment variables
Rafael Garcia-Suarez
interesting exercise. So I can write CGI scripts. Maybe. But I don't
know what's the Right way to do it in Perl 6. Any hints ?
--
#!/usr/bin/pugs
say "Just another Pugs hacker";
Autrijus Tang
> This might initially work for read-only access/testing, but in
> the long run I suspect that %*ENV will be tied directly to the
> C putenv/getenv calls or their Parrot/other equivalents.
> Assigning to %*ENV should change the environment for any scripts
> invoked from Perl 6.
Right, I was just saying that to rgs on #perl6. :)
> (This also eliminates the runtime overhead of "populating %*ENV"
> when it's not going to be used by a particular script.)
Yup. This may very well be our first example of an IType.
Thanks,
/Autrijus/
Autrijus Tang
> I had this silly idea, to try to add %ENV to pugs. That would be an
> interesting exercise. So I can write CGI scripts. Maybe. But I don't
> know what's the Right way to do it in Perl 6. Any hints ?
In Perl6 I think you do it by populating the %*ENV hash, when the
script is first run. To add it, hack Main.hs line 102 to add a new
SGlobal symbol of a VHash. If you already have a list of pairs "x",
it is as simple as:
VHash $ MkHash (listToFM x)
Now, to obtain the list of ENV, hack Posix.hs to add an import of
System.Posix.Env, and you'll have a that list of pairs via the
"getEnvironment" call:
x <- getEnvironment
Find me on #perl6 if you're unsure how to approach this. :)
Thanks,
/Autrijus/
Patrick R. Michaud
> jn Tue, Feb 22, 2005 at 10:54:26AM -0000, Rafael Garcia-Suarez wrote:
> > I had this silly idea, to try to add %ENV to pugs. That would be an
> > interesting exercise. So I can write CGI scripts. Maybe. But I don't
> > know what's the Right way to do it in Perl 6. Any hints ?
>
> In Perl6 I think you do it by populating the %*ENV hash, when the
> script is first run.
This might initially work for read-only access/testing, but in
the long run I suspect that %*ENV will be tied directly to the
C putenv/getenv calls or their Parrot/other equivalents.
Assigning to %*ENV should change the environment for any scripts
invoked from Perl 6.
(This also eliminates the runtime overhead of "populating %*ENV"
when it's not going to be used by a particular script.)
Pm
Rafael Garcia-Suarez
> jn Tue, Feb 22, 2005 at 10:54:26AM -0000, Rafael Garcia-Suarez wrote:
> > I had this silly idea, to try to add %ENV to pugs. That would be an
> > interesting exercise. So I can write CGI scripts. Maybe. But I don't
> > know what's the Right way to do it in Perl 6. Any hints ?
>
> In Perl6 I think you do it by populating the %*ENV hash, when the
> script is first run. To add it, hack Main.hs line 102 to add a new
> SGlobal symbol of a VHash. If you already have a list of pairs "x",
> it is as simple as:
>
> VHash $ MkHash (listToFM x)
Here's a patch to add this. It's heavily cargo-culted, I need to read
some docs about haskell some day. As I wasn't able to get FiniteMaps to
work I implemented my own kludgy function to flatten pairs for the hash.
Also I suspect that the type of the internal thingy in %*ENV might not
be right, so you may want to turn it in a VHash instead (I haven't found
any difference).
Comes with tests. Note that this %*ENV is not magical. It should be
sufficient to write simple http-GET CGI scripts, though.
Index: t/op/magic.t
===================================================================
--- t/op/magic.t (revision 0)
+++ t/op/magic.t (revision 0)
@@ -0,0 +1,13 @@
+# Tests for magic variables
+
+use v6;
+
+say "1..2";
+
+# Tests for %*ENV
+
+# it must not be empty at startup
+if (0 + %*ENV.keys > 0) { say "ok 1"; } else { say "not ok 1"; }
+
+# PATH is usually defined. But this test is not portable
+if %*ENV{"PATH"} ne "" { say "ok 2"; } else { say "not ok 2"; }
Index: MANIFEST
===================================================================
--- MANIFEST (revision 170)
+++ MANIFEST (working copy)
@@ -71,6 +71,7 @@
t/op/hash.t
t/op/inc.t
t/op/join.t
+t/op/magic.t
t/op/pair.t
t/op/pop.t
t/op/push.t
Index: src/Main.hs
===================================================================
--- src/Main.hs (revision 170)
+++ src/Main.hs (working copy)
@@ -22,6 +22,7 @@
import Parser
import Help
import Pretty
+import Posix
main :: IO ()
main = do
@@ -92,14 +93,20 @@
runFile file = do
withArgs [file] main
+flattenPairs :: [(x,x)] -> [x]
+flattenPairs [] = []
+flattenPairs ((a,b):q) = [a,b] ++ flattenPairs q
+
runProgramWith :: (Env -> Env) -> (Val -> IO ()) -> VStr -> [VStr] -> String -> IO ()
runProgramWith fenv f name args prog = do
+ environ <- getEnvironment
env <- emptyEnv
[ Symbol SGlobal "@*ARGS" (Val $ VList $ map VStr args)
, Symbol SGlobal "@*INC" (Val $ VList [])
, Symbol SGlobal "$*PROGNAME" (Val $ VStr name)
-- , Symbol SGlobal "$*STDIN" (Val $ VStr str)
, Symbol SGlobal "$*END" (Val VUndef)
+ , Symbol SGlobal "%*ENV" (Val $ VList $ map VStr $ flattenPairs environ)
]
-- str <- return "" -- getContents
let env' = runRule (fenv env) id ruleProgram prog
Index: src/Posix.hs
===================================================================
--- src/Posix.hs (revision 170)
+++ src/Posix.hs (working copy)
@@ -21,9 +21,11 @@
rename,
removeLink,
sleep,
+ getEnvironment,
) where
#ifdef PUGS_HAVE_POSIX
+import System.Posix.Env
import System.Posix.Files
import System.Posix.Process
import System.Posix.Unistd
@@ -47,4 +49,7 @@
sleep :: Int -> IO ()
sleep _ = fail "'sleep' not implemented on this platform."
+getEnvironment :: IO [(String, String)]
+getEnvironment = []
+
#endif
Autrijus Tang
> Here's a patch to add this. It's heavily cargo-culted, I need to read
> some docs about haskell some day. As I wasn't able to get FiniteMaps to
> work I implemented my own kludgy function to flatten pairs for the hash.
> Also I suspect that the type of the internal thingy in %*ENV might not
> be right, so you may want to turn it in a VHash instead (I haven't found
> any difference).
Thanks, indeed a list of pairs may be casted, in Pugs internal, as a
hash at any time. To cast into VHash, use listToFM:
VHash . MkHash . listToFM $ [ (VStr k, VStr v) | (k, v) <- environ ]
But otherwise, the patch is clean. Applied, thanks!
/Autrijus/