I want to use Prolog with PHP. Is it possible?
There are always the exec-familiy functions to execute/spawn another process.
As suggested above, you can execute a Prolog interpreter or binary. However, most Prolog implementations also export a C API that can be used to call the Prolog interpreter.
You could create a small PHP module to start an interpreter and execute queries. For instance, the SICStus documentation describes using Prolog from C in detail:
6 Mixing C/C++ and Prolog
Most Prologs allow for prolog code to be compiled into a binary. You could try calling this binary from within PHP using some kind of process call as already mentioned.
I wrote a translator that can convert some simple PHP programs into Prolog and vice-versa.
This is a possible input program:
function is_greater_than($a,$b){
return $a > $b;
}
function is_an_animal($a){
return in_array($a,["dog","cat"]);
}
...and this is the output program:
is_greater_than(A,B) :-
A>B.
is_an_animal(A) :-
member(A,["dog","cat"]).
This translator is only a proof-of-concept, but it may still make it easier to convert some simple PHP programs into Prolog.
Related
I have been using PHP for a while now with my Apache2 web server on my raspberry pi. It works great, but I get tired of always having to think "how do I X in PHP" or "what was the function name for this in PHP".
I am under the strong impression that there should be something equivalent in which I can replace the <?php ?> code with python code, but my search results have been confusing at best.
I am essentially looking for something where I can write whatever python code I want in an HTML script and have it interpreted and executed and its output inserted into the page when it is requested.
For example, to make a table of users from a list in python.
<table><tr><td>User list</td></tr>
<?python
import json
library=json.load(open(some_json_file,'r'));
for user in library:
print "<tr><td>"+user+"</td></tr>"
?>
</table>
I'm under the impression that chameleon can do this with its code blocks as described here,(https://chameleon.readthedocs.io/en/latest/reference.html) but as I look deeper, I get the impression it doesn't work like I am thinking it should. This is the impression I have gotten from all of the template engines I have looked at, as well as WSGI
Are there good drop in python alternatives for PHP? Or are there ways to cleanly wrap semi complex python code into my php in way that doesn't involve writing an additional python script that is called by PHP? I've tried exec() with python -c; but this was less than ideal having to escape all the ' and " characters...
update
The below code works just fine, but can become very slow if run multiple times in a script (takes about 0.4 seconds each time on a raspberry pi3). I have written a program in python that runs in the background and handles requests from php, and runs about 15x faster. I'm now maintaining it here on github.
Original Answer
After messing around I was able to come up with something mostly suitable for what I am trying to do. Inside my php I create a function that executes python scripts.
<?php
function py($s){
exec("python -c '$s'",$arr);
foreach($arr as $v){
echo $v."\n";}
}
?>
Then I use php Heredoc(equivalent to python """ , means I don't have to escape every single double quote) to fill the function:
<?php
py(<<<python
print "Hello world<br>"
s="ello world"
for x in s:
print x+"<br>"
python
);
?>
outputs >>>
Hello world
e
l
l
o
w
o
r
l
d
the only real downside I am experiencing at this point is that this method precludes me from using single quotes anywhere in my python script... :(. I'll get over it.
EDIT
I added a few more tweaks to make this even more useful. The new function is below:
<?php
function py($s,$return=false){
$s=str_replace("'","'\''",$s);
$h=<<<head
def cleanup():
for x in globals().keys():
if not x.startswith("_"):
del globals()[x]
import dill
try:
dill.load_session("pyworking.pkl")
except:
pass
head;
$f=<<<foot
import dill
dill.dump_session("pyworking.pkl")
foot;
if ($return==false){
echo shell_exec("python -c '$h$s$f'");
}
else {
return shell_exec("python -c '$h$s$f'");
}
}
?>
this allows you to use single quotes in the script and invoke the py() function multiple times in the same script and your variables and modules will follow you. At the end of the script you just call the clean up (or using php clear the pyworking.pkl file) and wipe the environment clean.
I also put this function in a file and in my pyp.ini I used the auto_prepend_file=my/file/location to automatically include it, so no need to load it before hand.
Overall I am very happy with this method, especially since I can read php variables inside my python script. Passing objects is as simple as:
<?php
$data_en=json_encode($data);
py(<<<p
import json
data=$data_en
#do something with data
p
);
?>
this would be perfect if I could think of a way to assign values to php variables inside the script, but its not a bad workaround if you want a fusion of php and python or just a way to do everything in python without writing a python webserver (which i have also done).
Is there a PHP lib that provides similar functionality as the argparse module of Python? PHP's getopt certainly doesn't cut it.
What I need:
required param check and automatic error msg generation.
correct exit status on error ( > 0 if param parse error).
error msg's to STDERR.
help msg generation of all accepted params.
param type checking is a bonus.
Basically how a *NIX CLI script should behave.
The most comprehensive library i know of (and the only one i've actually used) is Console_CommandLine. I have not used argparse so I can't tell you if it is as featured or compare them.
You can use Zend_Console_GetOpt.
Docopt, an altogether beautiful command parser, has a PHP version.
I have a Python file I'm calling with PHP's exec function. Python then outputs a string (apparently Unicode, based on using isinstance), which is echoed by PHP. The problem I'm running into is that if my string has any special characters in it (like the degree symbol), it won't output. I'm sure I need to do something to fiddle with the encoding, but I'm not really sure what to do, and why.
EDIT: To get an idea of how I am calling exec, please see the following code snippet:
$tables = shell_exec('/s/python-2.6.2/bin/python2.6 getWikitables.py '.$title);
Python properly outputs the string when I call getWikitables.py by itself.
EDIT: It definitely seems to be something either on the Python end, or in transmitting the results. When I run strlen on the returned values in PHP, I get 0. Can exec only accept a certain type of encoding?
Try setting the LANG environment variable immediately before executing the Python script per http://php.net/shell-exec#85095:
shell_exec(sprintf(
'LANG=en_US.utf-8; /s/python-2.6.2/bin/python2.6 getWikitables.py %s',
escapeshellarg($title)
));
(use of sprintf() to (hopefully) make it a little easier to follow the lengthy string)
You might also/instead need to do this before calling shell_exec(), per http://php.net/shell-exec#78279:
$locale = 'en_US.utf-8';
setlocale(LC_ALL, $locale);
putenv('LC_ALL='.$locale);
I have had a similar issue and solved it with the following. I don't understand why it is necessary, since I though all is already processed with UTF-8. Calling my Python script on the command line worked, but not with exec (shell_exec) via PHP and Apache.
According to a php forum entry this one is needed when you want to use escapeshellarg():
setlocale(LC_CTYPE, "en_US.UTF-8");
It needs to be called before escapeshellarg() is executed. Also, it was necessary to set a certain Python environment variable before the exec command (found an unrelated hint here):
putenv("PYTHONIOENCODING=utf-8");
My Python script evaluated the arguments like this:
sys.argv[1].decode("utf-8")
(Hint: That was required because I use a library to convert some arabic texts.)
So finally, I could imagine that the original question could be solved this way:
setlocale(LC_CTYPE, "en_US.UTF-8");
putenv("PYTHONIOENCODING=utf-8");
$tables = shell_exec('/s/python-2.6.2/bin/python2.6 getWikitables.py ' .
escapeshellarg($title));
But I cannot tell anything regarding the return value. In my case I could output it to the browser directly without any problems.
Spent many, many hours to find that out... One of the situations when I hate my job ;-)
This worked for me
setlocale(LC_CTYPE, "en_US.UTF-8");
putenv("PYTHONIOENCODING=utf-8");
$tables = shell_exec('/s/python-2.6.2/bin/python2.6 getWikitables.py ' .
escapeshellarg($title));
On php you can use methods like utf8_encode() or utf8_decode() to solve your problem.
I have a great Python program on my webserver, which I want to use from inside my PHP web app.
Here's an example of the python command, and output as you would see it in terminal:
>>> print MBSP.parse('I ate pizza with a fork.')
I/PRP/I-NP/O/NP-SBJ-1/O/i
ate/VBD/I-VP/O/VP-1/A1/eat
pizza/NN/I-NP/O/NP-OBJ-1/O/pizza
with/IN/I-PP/B-PNP/O/P1/with
a/DT/I-NP/I-PNP/O/P1/a
fork/NN/I-NP/I-PNP/O/P1/fork ././O/O/O/O/.
You might recognize this as a typical POS tagger.
In any case, I'm confused about how to use a PHP-based web app to send this program a string like "I ate pizza with a fork", and somehow get the response back in a way that can be further parsed in PHP.
The idea is to use PHP to pass this text to the Python program, and then grab the response to be parsed by PHP by selecting certain types of words.
It seems like in PHP the usual suspects are popen() and proc_open(), but popen() is only for sending, or receiving information - not both? Is popen() able to give me access to this output (above) that I'm getting from the Python program? Or is there a better method? What about curl?
Here are all my options in terms of functions in PHP:
http://us.php.net/manual/en/function.proc-open.php
I'm lost on this, so thanks for your wise words of wisdom!
I use exec() for this purpose.
exec($command, $output);
print_r($output);
If you want to get a little heavier / fancier... give your python script an http (or xmlrpc) front end, and call that with a GET/POST. Might not be worth all that machinery though!
You could use popen(), and pass the input to your Python script as a command line argument, then read the output from the file descriptor popen gives you, or proc_open() if you want to interact bi-directionally with the Python script.
Example 1 in the proc_open manual: http://us.php.net/manual/en/function.proc-open.php gives an example of this.
If your Python needs it as stdin, you could try popening a command line:
echo "I ate pizza!"|my_python_progam.py
and just read the output. As usual, do proper input validation before sending it to the command-line.
Something like this would work
$command = '/usr/bin/python2.7 /home/a4337/Desktop/script.py'
$pid = popen('$command',r)
........
........
.........
pclose($pid)
i'm trying to run one c executable file using php exec().
When c contains a simple program like print hello. I'm using
exec('./print.out')
It's working fine. But when I need to pass a argument to my c program I'm using
exec('./arugment.out -n 1234')
It is not working. Can any body tell me how to pass arugment using exec to c program.
From taking a look at the php documentation, it appears that exec treats arguments a bit oddly. You could try doing
exec("./argument.out '-n 1234'")
to prevent it from mangling them (it normally separates them all on space, which might be what's messing it up).