create function at runtime

[invincible]

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

thanks

Mohan

[Richard Bos]

"invincible " <mo**********@i n.bosch.com> wrote:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

You cannot. Not in ISO C, anyway; and not in any dialect of C that I'm
aware of without resorting to the most hairy of hacks. It would probably
involve writing machine code directly, and you really don't want to do
that unless you absolutely must. Note that "absolutely must" includes
"cannot possibly use a language which is better suited for this; at a
pinch, even using Clipper will be better than munging your own code
space."

Richard

[DeltaOne]

Well there is no facility in C language for this. Well if you want to
create something like this you can try ony way that is giving a feel
that actually you are creating a function at run time but in actual you
dont...You take input and parse the input yourself and the if a
statement like this is there::
printf("hello world")
then make it str="hello World";
and puts(str);

[Chris McDonald]

"DeltaOne" <sh**********@w ipro.com> writes:

Well there is no facility in C language for this. Well if you want to
create something like this you can try ony way that is giving a feel
that actually you are creating a function at run time but in actual you
dont...You take input and parse the input yourself and the if a
statement like this is there::
printf("hell o world")
then make it str="hello World";
and puts(str);

<OT>
.... or your process writes the C text to a file, spawns other
processes to compile and link the C, then dynamically load the resulting
shared object into the running process, if your operating system
supports it.
</OT>

--
Chris.

[Keith Thompson]

"invincible " <mo**********@i n.bosch.com> writes:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

Probably by implementing a Lisp interpreter in C.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Chris McDonald]

Keith Thompson <ks***@mib.or g> writes:

"invincible " <mo**********@i n.bosch.com> writes:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

Probably by implementing a Lisp interpreter in C.

or a C interpreter in C:

http://www.softintegration.com/products/chstandard/

--
Chris.

[Mark McIntyre]

On Thu, 19 May 2005 06:29:33 GMT, in comp.lang.c ,
rl*@hoekstra-uitgeverij.nl (Richard Bos) wrote:

"invincible " <mo**********@i n.bosch.com> wrote:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

You cannot. Not in ISO C, anyway; and not in any dialect of C that I'm
aware of without resorting to the most hairy of hacks.

You could write an interpreter, and your C programme could write the
fn out to file / into memory, invoke the interpreter on it, and
process the results.

--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt >

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[Flash Gordon]

Chris McDonald wrote:

"DeltaOne" <sh**********@w ipro.com> writes:

Well there is no facility in C language for this. Well if you want to
create something like this you can try ony way that is giving a feel
that actually you are creating a function at run time but in actual you
dont...You take input and parse the input yourself and the if a
statement like this is there::
printf("hel lo world")
then make it str="hello World";
and puts(str);

<OT>
... or your process writes the C text to a file, spawns other
processes to compile and link the C, then dynamically load the resulting
shared object into the running process, if your operating system
supports it.
</OT>

Or you embed a C interpreter written in standard C in your program.
--
Flash Gordon
Living in interesting times.
Although my email address says spam, it is real and I read it.

[Richard Bos]

Mark McIntyre <ma**********@s pamcop.net> wrote:

On Thu, 19 May 2005 06:29:33 GMT, in comp.lang.c ,
rl*@hoekstra-uitgeverij.nl (Richard Bos) wrote:

"invincible " <mo**********@i n.bosch.com> wrote:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

You cannot. Not in ISO C, anyway; and not in any dialect of C that I'm
aware of without resorting to the most hairy of hacks.

You could write an interpreter, and your C programme could write the
fn out to file / into memory, invoke the interpreter on it, and
process the results.

Sure, but that's a whole different thing. Then you're creating _another_
programming environment within the larger program, the language of which
may be deceptively similar to the one your main program is written in.
AFAIAA all lambda functions in all Lisp-alikes create new functions as a
part of the main program itself.

Richard

[Arafangion]

Chris McDonald wrote:

Keith Thompson <ks***@mib.or g> writes:

"invincible " <mo**********@i n.bosch.com> writes:

hi friends , how can I declare / create function during runtime similiar to
lambda in lisp.

Probably by implementing a Lisp interpreter in C.

or a C interpreter in C:

http://www.softintegration.com/products/chstandard/

www.enlightenment.org has a nice implementation of Small, a C-like
language, called Embryo.
Apparently it's very fast, and contains a small subset of C.