Re: libapl apl_exec results displayed as ?

[Chris Moller]

Yeah, I don't understand a path from a result code integer to a stdout character, which is why I suspect there's something going on in the freepascal-C interface.  Many years ago, I worked with a Java-to-C interface which was not straight-forward.  Maybe the freepascal-C interface is similarly weird.

On 7/25/22 11:46, Dr. Jürgen Sauermann wrote:

Hi,








All the magic happens at *StateIndicator.cc* line *542 ff*.

Best Regards,
Jürgen


On 7/25/22 4:49 PM, Chris Moller wrote:

0 is an error code, pretty much ⎕ET on page 287 of the APL language reference. The major error code, i.e. ↑⎕ET, is the same as in APL2, the minor error code 1↓⎕ET may differ. It has no relation to ⎕IO. I can't currently see how the result code would make its way to stdout, maybe the caller prints it? Currently the callback gets a const value (so it cannot modify it) and an int telling if the values is committed (aka, assigned to a vatiable) or not (which then causes apl to print it). Maybe think of apl_exec("FOO") to be essentially  ⍎"FOO" so that any printouts produced by FOO would be apl output. Not sure, though. As far as (lib-)apl is concerned the callback decides if the result of ⍎"FOO"  will be printed.

Sorry, but I have no idea how the interface between freepascal and C libraries works.  If your ⎕io is set to 1, the default, there's certainly no obvious reason for an ASCII 0 to be emitted to stdout.  Does freepascal start foreign code in a separate process?  Without reopening stdout?

On 7/24/22 17:49, enz...@gmx.com wrote:

Hi

i can see you code is c++

I am working with libapl with fpc (freepascal) and i can capture stdout and 
stderr fine in fpc coding
but the only stdout i get from ap_exec is the 0

i have apl_exec as a function and tried with either of the following definitions

function apl_exec(p : pchar) : longint; cdecl; // gives good results displayed 
but stdout captures only 0

function apl_exec(p : pchar) : ansistring; cdecl; // gives nothing to screen 
with apl_exec nor any stdout





On Sun, 24 Jul 2022 17:16:10 -0400

Chris Moller<mol...@mollerware.com>  wrote:

apl_exec() can output to both stdout and stderr.

I use:


std::stringstream outbuffer;
       std::streambuf *coutbuf = std::cout.rdbuf();
       std::cout.rdbuf(outbuffer.rdbuf());
       std::stringstream errbuffer;
       std::streambuf *cerrbuf = std::cerr.rdbuf();
       std::cerr.rdbuf(errbuffer.rdbuf());
       execerr = apl_exec (cmd.toStdString ().c_str ());
       std::cout.rdbuf(coutbuf);
       std::cerr.rdbuf(cerrbuf);
       outString = QString (outbuffer.str ().c_str ());
       errString = QString (errbuffer.str ().c_str ());

On 7/24/22 16:12,enz...@gmx.com  wrote:

hello

What does libapl output?- the apl_exec function returns 0 to stdout but what is 
the actual display?

for example  apl_exec('⍳20')  what/where is the 1 to 20 displayed so it can be 
captured?

thanks

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