#7482: provide a mode so that undeclared variables magically spring into
existence
and object oriented notation is not necessary
---------------------------+------------------------------------------------
Reporter: was | Owner: tbd
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.3
Component: misc | Keywords:
Work_issues: | Author:
Reviewer: | Merged:
---------------------------+------------------------------------------------
Comment(by was):
I have created a "mock up" of the above functionality, for people to play
with, which doesn't even require applying a patch. Just paste the
following into a Sage notebook cell and press shift-enter:
{{{
class MagicVar(Expression):
def __call__(self, *args, **kwds):
return args[0].__getattribute__(str(self))(*args[1:], **kwds)
class MagicNames:
def eval(self, s, globals, locals=None):
x = preparse(s).strip()
y = x.split('\n')
if len(y) == 0:
return ''
s = '\n'.join(y[:-1]) + '\n'
t = y[-1]
try:
z = compile(t + '\n', '', 'single')
except SyntaxError:
s += '\n' + t
z = None
while True:
try:
self._eval_code(s, z, globals)
except NameError, msg:
nm = msg.args[0].split("'")[1]
globals[nm] = MagicVar(SR, var(nm))
else:
return ''
def _eval_code(self, s, z, globals):
eval(compile(s, '', 'exec'), globals, globals)
if z is not None:
eval(z, globals)
magic = MagicNames()
}}}
Now if you put %magic at the top of an input cell, then symbolic variables
magically spring into life, and object oriented notation is not necessary.
There isn't an easy way to make this permanent for all cells in a
worksheet (without putting %magic) without actually changing the sage
library with a patch. This is because of a major annoying mistake I found
just now (see #7483).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7482#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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