That is surely a bug. I always assumed that the only trabformation
made when inputting a .sage file whe nit is converted to a .py file
was to apply the same preparsing as when you type into the command
line. But that is not the case: note that
preparse('0 = 42')
returns
'__tmp__=var("0"); Integer = symbolic_expression(Integer(42)).function(0)'
which fails because var() -- more specifically SR.var() -- tests its input.
Does anyon know why the .sage --> .py conversion is any different?
John
On 20 October 2016 at 10:00, Bruno Grenet <bruno.gre...@gmail.com> wrote:
> Consider the following code:
>
> 0 = 42
> print 0
>
> If you write it into sage's ipython, it of course gives you an error. More
> precisely, you get
> ValueError: The name "0" is not a valid Python identifier.
>
> But suppose you write it into a file bug.sage, and execute it using sage
> bug.sage, you get 42! The explanation is actually pretty simple: when you
> execute sage bug.sage, bug.sage is preparsed to bug.sage.py which is the
> following:
>
> # This file was *autogenerated* from the file bug.sage
> from sage.all_cmdline import * # import sage library
>
> _sage_const_42 = Integer(42); _sage_const_0 = Integer(0)
> _sage_const_0 = _sage_const_42
> print _sage_const_0
>
>
> Since 0 is replaced by _sage_const_0, you can affect any value to it.
>
> Is this a known bug? Is there a way in Python to declare that _sage_const_i
> is immutable?
>
> I wanted to open a ticket, but as noticed by Dima, trac seems to be down...
>
> Bruno
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "sage-devel" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sage-devel+unsubscr...@googlegroups.com.
> To post to this group, send email to sage-devel@googlegroups.com.
> Visit this group at https://groups.google.com/group/sage-devel.
> For more options, visit https://groups.google.com/d/optout.
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/d/optout.
