From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED.3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Running a simple Python from Ada program
Date: Fri, 3 Apr 2020 22:06:49 +0200
Organization: Aioe.org NNTP Server
Message-ID: <r6850n$1p1t$1@gioia.aioe.org>
References: <e5076a57-5f9d-43eb-bac9-1bf016237389@googlegroups.com>
 <r67s4q$16a3$1@gioia.aioe.org>
 <d067dcb5-a763-48e0-a142-af8446f2184e@googlegroups.com>
 <e1993dba-8fa0-4dcf-85cb-63625c704fe6@googlegroups.com>
NNTP-Posting-Host: 3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.6.0
X-Notice: Filtered by postfilter v. 0.9.2
Content-Language: en-US
Xref: reader01.eternal-september.org comp.lang.ada:58303
Date: 2020-04-03T22:06:49+02:00
List-Id: <comp.lang.ada>

On 2020-04-03 21:19, Rego, P. wrote:
>>> Do not do that. There exist Python C API, which you should use:
>>>      https://docs.python.org/3/c-api/index.html
>> You mean that the problem is with the Python "print" ?
> 
> I tested with a very simple C code. If the Python print is blocked, it should be blocked also from a C call, I presume (ok someone will contest, anyway). Any case, from the C call, it does not block.
> 
> So I will try to simplify a bit the question. I want to do the equivalent of this
> 
>      #include <stdio.h>
>      #include <stdlib.h>
>      int main(){
>        system("python testpy.py ddddd");
>        return 0;
>      }
> In this case it does not block the testpy.py printouts.
> 
> But I am doing this
>      with Interfaces.C; use Interfaces.C;
>      procedure systest2 is
>         function Sys (Arg : Char_Array) return Integer;
>         pragma Import(C, Sys, "system");
>         Ret_Val : Integer;
>      begin
>         Ret_Val := Sys(To_C("python testpy.py arg1 arg2"));
>      end systest2;
> which blocks the testpy.py script until its end. This should not happen.

It must, actually:

https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/system-wsystem?view=vs-2019

> So, please, how could I fix this?

You need spawn python in an asynchronous process or else a batch script 
with something like "call python test.py ddddd" inside.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de