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4.9.5.1 Ssi file links
Ssi file links provide the possibility to store data in a file using the
ssi format.
For storing large amounts of data, ssi file links
should be used instead of ASCII links. Unlike ASCII links, data read
from ssi file links is returned as expressions one at a time.
The ssi file link describing string has to be one of the following:
"ssi:r " + filename
opens the file for reading.
"ssi:w " + filename
opens the file for overwriting.
"ssi:a " + filename
opens the file for appending.
Note that the filename may contain a path. An ssi file link can be used
either for reading or for writing, but not for both at the same time. A
close command must be used before a change of I/O direction.
Example:
| | ring r;
link l="ssi:w example.ssi"; // type=ssi, mode=overwrite
l;
==> // type : ssi
==> // mode : w
==> // name : example.ssi
==> // open : no
==> // read : not open
==> // write: not open
ideal i=x2,y2,z2;
write (l,1, i, "hello world");// write three expressions
write(l,4); // append one more expression
close(l); // link is closed
// open the file for reading now
read(l); // only first expression is read
==> 1
kill r; // no basering active now
def i = read(l); // second expression
// notice that current ring was set, the name was assigned
// automatically
listvar(ring);
==> // ssiRing0 [0] *ring
==> // flint_poly_Q [0] cring
==> // ZZ [0] cring
==> // QQ [0] cring
def s = read(l); // third expression
listvar();
==> // s [0] string hello world
==> // ssiRing0 [0] *ring
==> // i [0] ideal, 3 generator(s)
==> // l [0] link
close(l); // link is closed
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