Sharing data between libraries

[Jon Kneller]

I have 2 seperate libraries, compiled to .so files (these are being loaded
into a Tcl process).

I would like to be able to share data (a linked list) between these
libraries - one needs to modify the data, the other needs to search it. I
cannot be certain that both libraries will loaded at any given time.
Because the program using the libraries is Tcl, I can't store the data at
that level.

Any ideas on how I can achieve this?

Thanks,
Jon

[Dan Pop]

In <cb***********@sp15en20.hursley.ibm.com> "Jon Kneller" <kn*****@uk.ibm.com> writes:

I have 2 seperate libraries, compiled to .so files (these are being loaded
into a Tcl process).

I would like to be able to share data (a linked list) between these
libraries - one needs to modify the data, the other needs to search it. I
cannot be certain that both libraries will loaded at any given time.
Because the program using the libraries is Tcl, I can't store the data at
that level.

Any ideas on how I can achieve this?

What was your C language question?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

[kal]

"Jon Kneller" <kn*****@uk.ibm.com> wrote in message news:<cb***********@sp15en20.hursley.ibm.com>...

I have 2 seperate libraries, compiled to .so files (these are being loaded
into a Tcl process).
<snip>
Any ideas on how I can achieve this?

If "Tcl" is yet another language/environment then there
probably are newsgroups for that. My $0.02 would be to
get rid of one or both the libraries.

[Jon Kneller]

Thanks. I have tried comp.lang.tcl with no luck - merging the libraries is
an option but a messy one (unfortunately most of the options available seem
at least a little messy...)

Jon

"kal" <k_*****@yahoo.com> wrote in message
news:a5**************************@posting.google.c om...

"Jon Kneller" <kn*****@uk.ibm.com> wrote in message news:<cb***********@sp15en20.hursley.ibm.com>...

I have 2 seperate libraries, compiled to .so files (these are being loaded into a Tcl process).

<snip>

Any ideas on how I can achieve this?

If "Tcl" is yet another language/environment then there
probably are newsgroups for that. My $0.02 would be to
get rid of one or both the libraries.

[Jon Kneller]

Sorry, I have just read my post back and it was far from clear.

The question was, can I share data between 2 shared libraries in C, when
these libraries are loaded into a C program which cannot change? Is it
possible to call functions in one from the other? Is it possible to
reference data in one from the other? Is there another way to have the
libraries share data that I haven't seen?

I am investigating shared memory at the moment but am unsure if there is a
better approach.

Jon

"Dan Pop" <Da*****@cern.ch> wrote in message
news:cb**********@sunnews.cern.ch...

In <cb***********@sp15en20.hursley.ibm.com> "Jon Kneller" <kn*****@uk.ibm.com> writes:

I have 2 seperate libraries, compiled to .so files (these are being loadedinto a Tcl process).

I would like to be able to share data (a linked list) between these
libraries - one needs to modify the data, the other needs to search it. Icannot be certain that both libraries will loaded at any given time.
Because the program using the libraries is Tcl, I can't store the data at
that level.

Any ideas on how I can achieve this?

What was your C language question?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

[Dan Pop]

In <cb***********@sp15en20.hursley.ibm.com> "Jon Kneller" <kn*****@uk.ibm.com> writes:

Sorry, I have just read my post back and it was far from clear.

The question was, can I share data between 2 shared libraries in C, when
these libraries are loaded into a C program which cannot change? Is it
possible to call functions in one from the other? Is it possible to
reference data in one from the other? Is there another way to have the
libraries share data that I haven't seen?

There is nothing library specific in your questions. Once your C
libraries are becoming part of your program, everything should work as
normal (a global variable defined in one library and declared in the
other is transparently shared between the two libraries). Think about
things like stdin and stdout, usually defined in one shared library.
Ditto about calling fprintf from another library.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de