running produced python code

[Skaperen]

is there a way to get the Python engine to exec some command or script via a pipe and read the python code from that pipe as the code it will interpret? i have seen programs that read something from a file accept a '|' as the first character of a file name and treat the remaining characters as a command string and run that command to produce the contents. i have a couple cases where i would sometimes like to invoke the python command that way.

i've been thinking of adding this capability to my zopen() function. but that is not something the python engine uses.

[BashBedlam]

On Linux, this script will remove blank lines from a text file when used like this:

cat text.txt | ./remove

Remember tochmod +x remove

#!/usr/bin/python3

from sys import stdin 

for line in stdin :
	if line != '\n' :
		print (line, end = '')

I don't know if it will work on Windows or not

[Skaperen]

that's not what i am looking for. i an looking for a way to support "|" at the start of a file name string and have it work as a command to execute. the command to execute is after the "|". the output of the command is the contents to be used by the program as if from a file. if the python engine supported this and foo.py outputted the python code to be run then you could do 'python "|python foo.py"' to run that code. but it does not support that. i am looking for a way to accomplish this.

[Gribouillis]

Why not simply write your own script named ppython such that the command

Output:
ppython foo.py

would run python foo.py, read its output as Python code and execute this Python code?

Alternatively suppose we have the following script

# paillasse/pf/spamm.py

print("""\
for i in range(5):
    print(i, i**2)

print("That's all folks!")
""")

Then here is what I can do in the bash shell by using python -c and command substitution

Output:
λ python -c "$(python paillasse/pf/spamm.py)"
0 0
1 1
2 4
3 9
4 16
That's all folks!
λ 

[Skaperen]

i'm not following that. maybe i need to read it a few more times.

the command line that outputs the python code to be run cannot have that code hardcoded in its own code. i need to be able to build any command line including those that get code somewhere on the internet at an unexpected place.

i am thinking of a wrapper that runs commands and saves output as temporary files then runs the real python with those temporary file names replacing the pipe prefix command string arguments. then i could adapt this for other commands.

i think that would work so i am thinking of a scheme to have just one such script that can figure out what is to really be run based on what command it replaces, such as /usr/local/bin/pythonxy will run /usr/bin/pythonxy after it saves the temporary files. that way i don't need to code a new script for each case. i would just symlink /usr/local/bin/pythonxy -> /usr/local/bin/usr.bin.wrapper and would figure out the path to the real executable.

[Gribouillis]

In my example, spamm.py could as well fetch the code somewhere on the internet. It does not need to be hard coded. May I suggest not to execute blindly code found on the internet

[Skaperen]

"on the internet" can include securely verified and trusted sources. then it's not "blindly". or the command could construct code based on info/data from various sources. it's up to whoever determines the command to do it right.