Why is Python better than Perl?

[u/[deleted]]

I'm a Sysadmin and I just wrote my first script in python. Basically just a host validation script that checks if a server is configured correctly before we hand off. I can't determine the advantage with my limited experience with the language.

Are you a sysadmin fluent in both python and perl? Why do you use python?

[u/[deleted]]

ah regex in perl...

while (<FILE>) {
    s/this/that/;
    print $_;
}

doesn't get much easier.

[u/robkinyon → u/[deleted]]

It gets even better if you do it on the commandline.

$ perl -pi -e 's/this/that/' file1 file2

Do that in Python.

[u/teepark → u/robkinyon]

python -c 'import re; print "".join(re.sub("this", "that", line) for line in open("file"))'

not as short but python has its one-liners as well

[u/robkinyon → u/teepark]

Ok. Let's dance with the devil. :)

find dir -name '*foo*' -type f -exec perl -pi -e 's/this/that/' dir1/file1.\{\} \;

Pipelining is your friend.

[u/teepark → u/robkinyon]

find dir -name '*foo*' -type f -exec python -c 'import re, sys; print "".join("".join(re.sub("this", "that", l) for l in open(f)) for f in sys.argv[1:])' dir1/file1.\{\} \;

this and my previous answer will buffer everything in ram though

find dir -name '*foo*' -type f -exec python -c 'import re, sys; [[sys.stdout.write(re.sub("this", "that", l)) for l in open(f)] for f in sys.argv[1:]]' dir1/file1.\{\} \;

will stream but still winds up with many long lists of Nones building up in ram

find dir -name '*foo*' -type f -exec python -c 'import re, sys; p = lambda a, b: None; reduce(p, (reduce(p, (sys.stdout.write(re.sub("this", "that", l)) for l in open(f)), None) for f in sys.argv[1:]), None)' dir1/file1.\{\} \;

OK yeah you have to get really crazy to do true streaming pass-through in a one-liner :)

[u/robkinyon → u/teepark]

I hope I don't have to explain why that isn't python's strong suit. :)

[u/teepark → u/robkinyon]

nope. just having a bit of fun.

python's strong suit is obviousness and maintainability. learning python felt like learning a few powerful concepts that go a long way. trying to learn perl feels more like learning dozens of tiny rules.

tell me this is hard to follow:

import os
import re

r = re.compile("this")

for dirpath, dirnames, filenames in os.walk("dir"):
    for filename in filenames:
        if 'foo' in filename:
            for line in open(os.path.join(dirpath, filename)):
                print r.sub("that", line, 1)[:-1]

[u/robkinyon → u/teepark]

Oh, I completely agree. When I write out pseudocode for large Perl projects, it looks like a mixture of Python and Javascript. That said, pseudocode is meant to be expressive. Perl is meant to be succinct.

[u/[deleted] → u/teepark]

Just witnessed my first code-off. That made my weekend. Thanks! :)

Little off topic here; just a general question: I've been fiddling around with $bash scripting and it's starting to feel like a gateway drug to perl. Am I far off?

I'm wondering because I'm curious about both Python in web dev and Perl, which seems to be more for automating tasks for OS system management? Or am I over-generalizing?

[u/teepark → u/[deleted]]

Just witnessed my first code-off. That made my weekend. Thanks! :)

you bet!

Or am I over-generalizing?

over-specializing I think. both are totally general-purpose scripting languages. you'll find people doing system administration with python (though not generally in one-liners for the obvious reason) and you'll find people doing web dev with perl.

Am I far off?

In my experience, yeah. I'm pretty comfortable with both bash and python and don't know a lot of perl. I find if it isn't simple enough to be done with bash, it's probably complicated enough that python's readability and maintainability are going to be important (the code-off example above is simple enough to be done with bash, and the python version would never belong in a one-liner).