#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):
Here is a session (to be used in the notebook) that illustrates
automatic_names:
{{{
sage: automatic_names(True)
sage: x + y + z + wxy
wxy + x + y + z
sage: y(y=10)
10
sage: type(y)
<class 'sagenb.misc.support.AutomaticVariable'>
sage: trig_expand((2*x + 4*y + sin(2*theta))^2)
4*(sin(theta)*cos(theta) + x + 2*y)^2
sage: type(trig_expand)
<class 'sagenb.misc.support.AutomaticVariable'>
sage: type(x)
<type 'sage.symbolic.expression.Expression'>
sage: type(y)
<class 'sagenb.misc.support.AutomaticVariable'>
}}}
Notice above that trig_expand, y, and theta were all automatically
created. Notice that substitution {{{y(y=10)}}} still works. If an
object obj had a y method, then y(obj) would be evaluated as obj.y().
Here's a test showing that we avoid infinite loops:
{{{
sage: raise NameError
Traceback (most recent call last):
...
NameError
sage: raise NameError, "'var'"
Traceback (most recent call last):
...
NameError: Too many automatic variable names and functions created
(limit=10000)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7482#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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