Support saving/loading sym objects from files

[cbm755]

I've been meaning to look at saving sym objects to disk. They are really just a structure with a few fields. Only x.pickle (currently char(x) but #375 might change that) is actually important as far as SymPy is concerned.

1. I've never promised API stability of that structure, might need to stabilize the structure a bit too. Or at least read about loading/saving @ classes.
2. Should we rename x.pickle to x.srepr? It was originally a pickle but has not been for a long time. See also Expressions with more than 255 terms cause communication failures #269.

[cbm755]

How to start: look at "saveobj" and "loadobj" methods.

[genuinelucifer]

@cbm755 Should I develop 2 new functions saveobj and loadobj which would save the object (passed as argument) using python code?
else,
To let users save it using inbuilt save and load, I'll have to implement saveobj function in the sym class. How do I do that?

[cbm755]

I'll have to implement saveobj function in the sym class. How do I do that?

Create a inst/@sym/saveobj.m file. And inst/@sym/loadobj.m.

(See the GNU Octave documentation for what they are supposed to do.)

A sym objection is basically a struct.

For loadobj, there is a special "magic" form of calling @sym/sym.m
which activates the constructor (see the source of that file).

[genuinelucifer]

Hi @cbm755
I almost completed the functions.
I also installed octave on my linux machine so as to test the files before submitting a PR. I get the following error when I try to use any command (for any file in inst/@sym/)

error: sq_string cannot be indexed with .
error: called from:
error:   /home/lucifer/GSoC/octsympy/inst/@sym/size.m at line 71, column 5
error:   /home/lucifer/GSoC/octsympy/inst/@sym/isempty.m at line 44, column 5
error:   /home/lucifer/GSoC/octsympy/inst/@sym/sym.m at line 169, column 3
error: evaluating argument list element number 1
error:   /home/lucifer/GSoC/octsympy/inst/@sym/ismember.m at line 65, column 5
error:   /usr/share/octave/3.8.1/m/help/__unimplemented__.m at line -1, column -1

[cbm755]

Are you saying you cannot run tests on some other OS? If so, please file a separate issue for that.

[cbm755]

This error looks familiar... Where are you running octave from? should be inst (not inst/@sym). Does that help?

[genuinelucifer]

Thanks. It worked from inst directory :)

[cbm755]

what about tests on Windows? Can you run them or not?

[genuinelucifer]

I guess yes. Only objective C tests are shown undefined. Other tests are passing.

[cbm755]

Closing