#17958: implement declare_var, deprecate (None)var
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Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.6
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by nbruin):
Replying to [comment:50 vbraun]:
> {{{
> sage: SR.inject_variables('x, y')
> sage: SR.inject_variables('x', 'y') # strings to variable names
> sage: SR.inject_variables('x{i}', i=range(10)) # use keyword
arguments to format
> sage: SR.inject_variables(ex) # inject all of ex.variables()
> }}}
Something like that would work, but probably not under that name. The
method already exists on `SR` by inheritance (and doesn't work), and the
signature you're proposing is incompatible with the one on other rings.
Injecting in general isn't really a method that belongs on the object,
since the object doesn't naturally have access to the dictionary into
which these things should be injected. It's really more the task of a REPL
utility function. In which case the spelling
{{{
inject_generators(QQ['x'])
}}}
would make more sense. The magic of figuring out into which dictionary the
bindings should be injected is compartmentalized into a single function
which could be implemented basically as
{{{
def inject_generators(parent):
D={repr(a): a for a in parent.gens()}
print "defining ",D.keys()
user_globals.update(D)
}}}
This probably much nicer than scattering references to user_globals all
over the place (we'd probably want to add some sanity checks to prevent
this from inserting objectionable bindings).
For symbolic binding we could then have something along the lines of
{{{
def inject_symbols(*args):
user_globals.update({ repr(a):a for e in args for a in e.variables()})
}}}
Interfacing via `%var` is then an additional measure.
In short, what we seem to be converging towards is:
- deprecate `sage.calculus.var.var` (but keep supporting it; after a
while probably do adorn it with a deprecation warning)
- support symbolic variable injection via a special `%var` directive
(which saves quotes too!) -- Is the `%` a problem? We'd need to make
doctests aware of it.
- have `SR.var(...)` as general symbol creation (which we already have).
There is some further rationalization around injection behaviour possible.
--
Ticket URL: <http://trac.sagemath.org/ticket/17958#comment:54>
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