On 11/2/07, William Stein <[EMAIL PROTECTED]> wrote:
> Ah, that's very very nice. OK, I would really like
> to see that implemented. Maybe Fernando Perez could
> tell us how to hook into IPython to make that happen....
Should be fairly straightforward. In iplib.py, around line 500,
you'll find this code:
# Functions to call the underlying shell.
# The first is similar to os.system, but it doesn't return a value,
# and it allows interpolation of variables in the user's namespace.
self.system = lambda cmd: \
shell(self.var_expand(cmd,depth=2),
header=self.rc.system_header,
verbose=self.rc.system_verbose)
# These are for getoutput and getoutputerror:
self.getoutput = lambda cmd: \
getoutput(self.var_expand(cmd,depth=2),
header=self.rc.system_header,
verbose=self.rc.system_verbose)
self.getoutputerror = lambda cmd: \
getoutputerror(self.var_expand(cmd,depth=2),
header=self.rc.system_header,
verbose=self.rc.system_verbose)
where 'shell', 'getoutput' and 'getoutputerror' are all defined in
IPython.genutils.
Simply take the ipython instance, and before you hand it to the user
for 'live' usage, change its
.system attribute to be your own routine which is similar to the above
lambda, but does the additional extra checks you want.
Basically code like (this is just a sketch):
import new
old_system = ipython_instance.system
def sage_system(self,cmd):
if cmd_in_sage_programs():
old_system(cmd)
else:
try:
update_environment()
old_system(cmd)
finally:
restore_environment()
ipython_instance.system = new.instancemethod(ipython_instance,sage_system)
This is obviously incomplete, but it should give you an idea of what's needed.
Cheers,
f
ps - at the NSF CDI meeting in Washington
http://www4.ncsu.edu/~kaltofen/CDI_SYMNUM_Itinerary.html
I made sure to have in my talk a slide about SAGE and to point out its
goals and importance. I didn't have much time for it, but hopefully
every bit helps.
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