Python newbie needs the help of Dr. OOP

Mr Green · 2006-07-14 16:27:23

#!/usr/bin/env python
#
# mpc.py
#
# Hacked by MrGreen
#

import os
import string
import re

def mpc():
 f= os.popen("mpc")
 mpc = f.readline()
 f.close()

 mpc = mpc[string.find(mpc, '/') +1:string.rfind(mpc, ".")]
 
 state = re.search('volume:', mpc)

 if  state:
         return "[Stopped]"
 else:
         return "[ %s ]" % mpc
 
print mpc()

:cry:

cactus · 2006-07-14 16:56:13

Maybe try changing the name of the function? You could be running into a namespace collision with mpc as the function name, and as variable names inside the function...

What is the actual error you are seeing?

Mr Green · 2006-07-14 17:18:29

dude I never get errors when I code rofl

Name change good call ... just used mpc while I was testing it

I wondered if I could clean it up more ?

/me prays Dr.OOP does not show up ;-)

cmp · 2006-07-14 18:22:02

out of curiosity what's the problem?

Mr Green · 2006-07-14 19:22:54

Not a problem as such more of a "Is this the right way to do it knida thing"

cmp · 2006-07-14 19:26:47

well i would wrap the whole thing as a class. where everything is stored as a variable. I'd maybe use a static method for the creation of the info object:

class MPCInfo:
  pass # details by you

info = MPCInfo.get()
print info.artist, info.title

Mr Green · 2006-07-14 19:44:35

emmmm nice wrap it up wonderd if I should add a def print_track_n_title as well?

import mpcinfo ?

Thanks

arooaroo · 2006-07-14 21:32:52

Mr Green wrote:

 mpc = mpc[string.find(mpc, '/') +1:string.rfind(mpc, ".")]

Wowsers! Just use a regular expression. It's easier to read for starters, and also it's easier to detect problems, should, for some reason, 'mpc' string doesn't contain the expected characters.

Mr Green · 2006-07-14 22:06:06

forgive me ... I was using output of mpc ... then pulling out artist - track

would re give me the same result ?

the '/' some of my tracks have a directory heading ...

deficite · 2006-07-15 03:36:23

I'm not aware of "cactusman". Is it new? I can't find it in pacman repos.

I'm sitting here trying to imagine what cactusman pages look like

cactus · 2006-07-15 05:03:23

deficite wrote:

I'm sitting here trying to imagine what cactusman pages look like

CACTUS(1)                                                                CACTUS(1)

NAME
       cactus - A desert plant known for standing around in the sun.

SYNOPSIS
       cactus [OPTION]

DESCRIPTION
       Do something kick ass on standard output.

       -S, --stand-duration
              How long to stand around.

       -D, --drink-water
              Absorb some quantity of water.

       -h, --help
              This help. Duh.

Mr Green · 2006-07-15 05:18:06

deficite wrote:

I'm not aware of "cactusman". Is it new? I can't find it in pacman repos.
I'm sitting here trying to imagine what cactusman pages look like

I thought Cactusman was part of base system, without it nothing works

arooaroo · 2006-07-15 09:57:27

Mr Green wrote:

forgive me ... I was using output of mpc ... then pulling out artist - track
would re give me the same result ?
the '/' some of my tracks have a directory heading ...

mpc = re.search(r'/(.+).', mpc).group(1)

(Off the top of my head)

This re will return all the text between the first forward-slash and the last fullstop. (not inclusive, of course). The parentheses denotes a "group". It's handy for isolating a particular part within the larger context. So the .group(1) method returns the contents within the first group. .group() returns the full re match, btw.

I've found Pyreb (http://pyreb.nongnu.org/) handy in testing regular expressions too.

tmadhavan · 2006-07-15 10:07:53

Seeing as there are a few pythonists lurking in here, any advice on where to start with Python?

I'm hoping to use it for a third year project in uni, just to force myself to learn something new as much as anything else. However, I have real difficulty just reading book after book, without doing any 'beginner' exercises.

I'm proficient with Java/C++ and the general OO way of doing things (paradigm, if you're into all that). I was wondering if anyone had any directions to exercises or articles/books they used.

I've searched a lot, reading Byte Of Python, and I also have Dive Into Python lying around. All well and good, but what about practicals? I realise this question is asked everywhere, I'm just wondering if you guys have any specific experience.

Cheers,
t

cmp · 2006-07-15 10:17:47

I just started with the library reference and the language reference. If you allready programm in another language this should be sufficent.
I would also recommend to use ipython (got tab completion - very nice) and inside ipython help() (interactive documentation).

arooaroo · 2006-07-15 10:34:33

The Python cookbook is also pretty handy, I've found:

http://aspn.activestate.com/ASPN/Python/Cookbook/

There's also a book called How to Think Like a Computer Scientist that's under a GNU license. It's very popular within universities and is in fact a guide of how to do lots of cool stuff in Python (although it's now been ported to other languages) for beginners.

http://greenteapress.com/thinkpython/

tmadhavan · 2006-07-15 10:47:17

Thanks very much for that guys. Forgot about that Thinking In Python. I did start to read it a while back, but never finished it.

I'll take a look at ipython, but one thing I don't understand with interactive shells is how to get them to just act like editors (which is totally pointless, I know). To write code, rather than be interactive. That's probably something I can just go and find out for myself.

Cheers again.

Any examples of the type of things you use Python for? I want to believe it's good for a lot more than scripting, which it does appear to be. Is there anywhere in general day to day coding (I don't know how that's defined) that Python falls down? I hear most (all?) of the system functions etc are coded in C deep down. Being weaned on Java, I like the appeal of Python's simplicity and clean code. Is it a substitute?

arooaroo · 2006-07-15 10:56:08

tmadhavan wrote:

Seeing as there are a few pythonists lurking in here, any advice on where to start with Python?
I'm hoping to use it for a third year project in uni, just to force myself to learn something new as much as anything else. However, I have real difficulty just reading book after book, without doing any 'beginner' exercises.
...
t

Basically, to get anywhere in python, you need to know four things:

1. How to read a file

for line in open('myfile.txt'):
  print line

2. Things you can do with strings:

http://docs.python.org/lib/typesseq.html

NB Remember that strings are immutable (that is, can't be changed in place) They need to be reassigned.

mystring = "TEST"
mystring.lower() # convert upper to lower
print mystring # still prints "TEST"!!!

mystring = mystring.lower() # reassign
print mystring # prints "test" woohoo!

3. Things you can do with lists

It's a big topic. But:

boffins = [] # empty list
boffins.append('cactus')
boffins.append('phracture')
boffins.append('arooaroo')

# or

boffins = ['cactus', 'phracture', 'arooaroo']

# iterate

for boffin in boffins:
  if boffin == "arooaroo":
    print "arooaroo is not a boffin"
  else:
    print boffin

# slicing lists

realboffins = boffins[0:2]
#or
realboffins = boffins[0:-1]
#etc

4. How to use regular expressions:

Again, it's a big topic. You can do lots with REs and once you get beyond the basic ones, they look bloody crytic to say the least.

I find Python's RE approach a tad too verbose when compared to Perl (I can't compare to Ruby though).

http://docs.python.org/lib/module-re.html

import re # need to import the re module first

mystring "<boffin>cactus</boffin><boffin>dusty</boffin>"

print re.search(r'<boffin>(.+?)</boffin>', mystring).group(1) # prints 'cactus'

boffinMatches = re.finditer(r'<boffin>(.+?)</boffin>', mystring)
for boffinMatch in boffinMatches:
  print boffinMatch.group(1)
# prints:
# cactus
# dusty

print re.sub(r'<boffin>cactus</boffin>', '<boffin>phracture</boffin>', mystring)
# prints "<boffin>phracture</boffin><boffin>dusty</boffin>"

And that's enough to get you started

EDIT: PS, I've not tested anything above and so excuse me for my small typos/mistakes

tmadhavan · 2006-07-15 15:38:48

Thanks a lot!

Really appreciate that, cheers.

T

cactus · 2006-07-15 18:29:31

A great starter:
http://diveintopython.org/toc/index.html

arooaroo · 2006-07-15 18:32:09

tmadhavan wrote:

...
I've searched a lot, reading Byte Of Python, and I also have Dive Into Python lying around. All well and good, but what about practicals?
...

cactus wrote:

A great starter:
http://diveintopython.org/toc/index.html

I think this one has been covered. Although, I guess it stresses that it should be *read* and not left lying around!

cactus · 2006-07-15 18:32:57

doh!

arooaroo · 2006-07-15 18:54:55

'sokay. Even the boffins can make (tiny) mistakes.

Mr Green · 2006-07-15 20:19:05

err like I totally lost it on the first page lol 8)

arooaroo · 2006-07-15 20:23:59

Mr Green wrote:

err like I totally lost it on the first page lol 8)

Pray tell, young man. Exactly where did you get lost?

Arch Linux

#1 2006-07-14 16:27:23

Python newbie needs the help of Dr. OOP

#2 2006-07-14 16:56:13

Re: Python newbie needs the help of Dr. OOP

#3 2006-07-14 17:18:29

Re: Python newbie needs the help of Dr. OOP

#4 2006-07-14 18:22:02

Re: Python newbie needs the help of Dr. OOP

#5 2006-07-14 19:22:54

Re: Python newbie needs the help of Dr. OOP

#6 2006-07-14 19:26:47

Re: Python newbie needs the help of Dr. OOP

#7 2006-07-14 19:44:35

Re: Python newbie needs the help of Dr. OOP

#8 2006-07-14 21:32:52

Re: Python newbie needs the help of Dr. OOP

#9 2006-07-14 22:06:06

Re: Python newbie needs the help of Dr. OOP

#10 2006-07-15 03:36:23

Re: Python newbie needs the help of Dr. OOP

#11 2006-07-15 05:03:23

Re: Python newbie needs the help of Dr. OOP

#12 2006-07-15 05:18:06

Re: Python newbie needs the help of Dr. OOP

#13 2006-07-15 09:57:27

Re: Python newbie needs the help of Dr. OOP

#14 2006-07-15 10:07:53

Re: Python newbie needs the help of Dr. OOP

#15 2006-07-15 10:17:47

Re: Python newbie needs the help of Dr. OOP

#16 2006-07-15 10:34:33

Re: Python newbie needs the help of Dr. OOP

#17 2006-07-15 10:47:17

Re: Python newbie needs the help of Dr. OOP

#18 2006-07-15 10:56:08

Re: Python newbie needs the help of Dr. OOP

#19 2006-07-15 15:38:48

Re: Python newbie needs the help of Dr. OOP

#20 2006-07-15 18:29:31

Re: Python newbie needs the help of Dr. OOP

#21 2006-07-15 18:32:09

Re: Python newbie needs the help of Dr. OOP

#22 2006-07-15 18:32:57

Re: Python newbie needs the help of Dr. OOP

#23 2006-07-15 18:54:55

Re: Python newbie needs the help of Dr. OOP

#24 2006-07-15 20:19:05

Re: Python newbie needs the help of Dr. OOP

#25 2006-07-15 20:23:59

Re: Python newbie needs the help of Dr. OOP

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