Here is my code to reload a python module using the reload() build in function. I have looked at some (not all :) ) the other questions and answers in stackoverflow but to get my code to work I still need to do a os.remove('m.pyc'). Can anybody maybe explain it to me or show me how I need to change my code to make the below work without the remove.
import os
open('m.py','wt').write(r'def f(str): print "Sooo Original : %s"%(str)')
import m
m.f('Original')
os.remove('m.pyc')
open('m.py','wt').write(r'def f(str): print "Not so original : %s"%(str)')
m = reload(m)
m.f('Copy')
By replacing your remove statement with time.sleep(1) to prevent both files from being created nearly simultaneously, I obtain the correct result. I guess the problem is that both files have the same time stamp which prevents Python from detecting the change and truly reload the module.
I get a different problem on my machine.
Traceback (most recent call last):
File "test.py", line 8, in <module>
m.f('Original')
AttributeError: 'module' object has no attribute 'f'
I've noticed that you didn't close your file, so it may that the contents of the file are being held in a buffer and are waiting to be written to disk. So when you come to reloading the module, python still sees the original version of the file.
From the documentation for file.write
write(...)
write(str) -> None. Write string str to file.
Note that due to buffering, flush() or close() may be needed before
the file on disk reflects the data written.
Does the following work for you?
f = open('m.py','wt')
f.write(r'def f(str): print "Sooo Original : %s"%(str)')
f.close()
import m
m.f('Original')
f = open('m.py','wt')
f.write(r'def f(str): print "Not so original : %s"%(str)')
f.close()
m = reload(m)
m.f('Copy')
Related
I'm trying to write some VERY trivial thing in pycharm.
Problem:
sourceText = ""
with open("lang.txt", "rt") as sourceFile:
sourceText = sourceFile.readall()
print sourceText
when I enter "." after "sourceFile", I get popup that offers me "readall()" method. However, when I attempt to run the script, I get"
Traceback (most recent call last):
....languages/languages.py", line 4, in <module>
sourceText = sourceFile.readall()
AttributeError: 'file' object has no attribute 'readall'
The method is documented (I get popup, can get documentation for this method using Ctrl+Q) but it seems to be inaccessible.
I'm a bit confused.
I'd like to either:
Not receive any popups for inaccessible methods in pycharm.
Or figure out why I can't see it despite it being documented.
Advice?
I'm using windows 7 64 bit, and have two python 2.7.9 installations (32bit and 64bit), with 64bit being in path 1st. Pycharm is 4.0.5 community edition.
You are correct that readall is documented for the io module, but it's complaining about file, which does not have that method. You want the read() method to read all the data in the file in one large clump. You could also use readlines() which well return a list. I have the Pro 3.4 edition of PyCharm and it does not do this. I would report this as a bug to PyCharm.
I am trying to use some temporary files in an little python script and running into problems while using the tempfile-module:
test-code
import tempfile
with tempfile.NamedTemporaryFile() as temp:
print temp.name
temp.write('Some data')
print temp.seek(0).read()
output
s$ python tmpFileTester.py
/var/folders/cp/8kmr4fhs4l94y8fdc6g_84lw0000gn/T/tmpcDgrzF
Traceback
(most recent call last): File "tmpFileTester.py", line 5, in
print temp.seek(0).read() AttributeError: 'NoneType' object has no attribute 'read'
--> This happens on my MacBook with MacOS 10.9 and Python 2.7.5, it also happens with "delete=False".
Any ideas? It's probably a noob-error, but I can't find the problem...
Whenever you are chaining methods in Python and you get this, you can bet that one of them returns None (even if implicitly by not returning at all). The solution is generally to split up the chain over multiple lines.
temp.seek(0)
print temp.read()
file.seek returns None.
You should separated following statement:
print temp.seek(0).read()
into two statements:
temp.seek(0)
print temp.read()
Hello everyone i am new to the python language and i have chosen learn python the hard way to learn it and to better my understanding... I am stumped on exercise 25 , When we import the code directly into the terminal
>>> import ex25
>>> sentence = "All good things come to those who wait."
>>> words = ex25.break_words(sentence)
And then I get an attribute error
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'break_words'
I am using python 2.7 on
windows 7 please help..... http://learnpythonthehardway.org/book/ex25.html
It appears to me that the exercise does not instruct the learner to save the file prior to the import. In order for this to work, you've got to save the code that defines the break_words function in a file called ex25.py using your text editor. Then, from the same directory open the python interpreter by typing:
python
and you should be able to import ex25 and run the break_words function which the ex25.py module has defined.
The code in your link for ex25.py does include that function - that yours doesn't suggests that you've somehow missed it when you transcribed the code into your file. Check that your ex25.py includes all the code from the page, and in particular contains this function (it's the very top one):
def break_words(stuff):
"""This function will break up words for us."""
words = stuff.split(' ')
return words
Consider pasting the code into your editor in preference to transcribing it in order to avoid errors like this.
I'm trying to save myself just a few keystrokes for a command I type fairly regularly in Python.
In my python startup script, I define a function called load which is similar to import, but adds some functionality. It takes a single string:
def load(s):
# Do some stuff
return something
In order to call this function I have to type
>>> load('something')
I would rather be able to simply type:
>>> load something
I am running Python with readline support, so I know there exists some programmability there, but I don't know if this sort of thing is possible using it.
I attempted to get around this by using the InteractivConsole and creating an instance of it in my startup file, like so:
import code, re, traceback
class LoadingInteractiveConsole(code.InteractiveConsole):
def raw_input(self, prompt = ""):
s = raw_input(prompt)
match = re.match('^load\s+(.+)', s)
if match:
module = match.group(1)
try:
load(module)
print "Loaded " + module
except ImportError:
traceback.print_exc()
return ''
else:
return s
console = LoadingInteractiveConsole()
console.interact("")
This works with the caveat that I have to hit Ctrl-D twice to exit the python interpreter: once to get out of my custom console, once to get out of the real one.
Is there a way to do this without writing a custom C program and embedding the interpreter into it?
Edit
Out of channel, I had the suggestion of appending this to the end of my startup file:
import sys
sys.exit()
It works well enough, but I'm still interested in alternative solutions.
You could try ipython - which gives a python shell which does allow many things including automatic parentheses which gives you the function call as you requested.
I think you want the cmd module.
See a tutorial here:
http://wiki.python.org/moin/CmdModule
Hate to answer my own question, but there hasn't been an answer that works for all the versions of Python I use. Aside from the solution I posted in my question edit (which is what I'm now using), here's another:
Edit .bashrc to contain the following lines:
alias python3='python3 ~/py/shellreplace.py'
alias python='python ~/py/shellreplace.py'
alias python27='python27 ~/py/shellreplace.py'
Then simply move all of the LoadingInteractiveConsole code into the file ~/py/shellreplace.py Once the script finishes executing, python will cease executing, and the improved interactive session will be seamless.
I am on windows with Python 2.5. I have an open file for writing. I write some data. Call file close. When I try to delete the file from the folder using Windows Explorer, it errors, saying that a process still holds a handle to the file.
If I shutdown python, and try again, it succeeds.
It does close them.
Are you sure f.close() is getting called?
I just tested the same scenario and windows deletes the file for me.
Are you handling any exceptions around the file object? If so, make sure the error handling looks something like this:
f = open("hello.txt")
try:
for line in f:
print line
finally:
f.close()
In considering why you should do this, consider the following lines of code:
f = open('hello.txt')
try:
perform_an_operation_that_causes_f_to_raise_an_exception()
f.close()
except IOError:
pass
As you can see, f.close will never be called in the above code. The problem is that the above code will also cause f to not get garbage collected. The reason is that f will still be referenced in sys.traceback, in which case the only solution is to manually call close on f in a finally block or set sys.traceback to None (and I strongly recommend the former).
Explained in the tutorial:
with open('/tmp/workfile', 'r') as f:
read_data = f.read()
It works when you writing or pickling/unpickling, too
It's not really necessary that try finally block: Java way of doing things, not Python
I was looking for this, because the same thing happened to me. The question didn't help me, but I think I figured out what happened.
In the original version of the script I wrote, I neglected to add in a 'finally' clause to the file in case of an exception.
I was testing the script from the interactive prompt and got an exception while the file was open. What I didn't realize was that the file object wasn't immediately garbage-collected. After that, when I ran the script (still from the same interactive session), even though the new file objects were being closed, the first one still hadn't been, and so the file handle was still in use, from the perspective of the operating system.
Once I closed the interactive prompt, the problem went away, at which I remembered that exception occurring while the file was open and realized what had been going on. (Moral: Don't try to program on insufficient sleep. : ) )
Naturally, I have no idea if this is what happened in the case of the original poster, and even if the original poster is still around, they may not remember the specific circumstances, but the symptoms are similar, so I thought I'd add this as something to check for, for anyone caught in the same situation and looking for an answer.
I did it using intermediate file:
import os
f = open("report.tmp","w")
f.write("{}".format("Hello"))
f.close()
os.system("move report.tmp report.html") #this line is for Windows users