with-statement Questions
3
I have a long-running process called an Updater, that has updates (to an ETL system) submitted to it. The updates have resource requirements that are managed by adding a context manager to the Upda...
Protocol asked 3/6, 2016 at 5:56
6
Solved
Is it possible to use the with statement directly with CSV files? It seems natural to be able to do something like this:
import csv
with csv.reader(open("myfile.csv")) as reader:
# do things with...
Remarkable asked 13/1, 2009 at 22:36
6
Solved
I am trying to do some shared locking using with statements
def someMethod(self, hasLock = False):
with self.my_lock:
self.somethingElse(hasLock=True)
def somethingElse(self, hasLock = False):...
Saenz asked 3/3, 2011 at 19:34
7
Solved
I would like to ensure that the class is only instantiated within a "with" statement.
i.e. this one is ok:
with X() as x:
...
and this is not:
x = X()
How can I ensure such functionality?
Stercoricolous asked 14/2, 2015 at 15:41
3
Solved
I am unsuccessfully trying to get the magic with-statement methods __enter__ and __exit__ running on class-level:
class Spam():
@classmethod
def __enter__(cls):
return cls
@classmethod
def ...
Holly asked 4/2, 2015 at 20:5
4
Solved
I'm often in the need of temporarily switching the value of a variable out with something else, do some computation which depends on this variable, and then restore the variable to its original val...
Kish asked 4/1, 2017 at 1:1
8
Solved
Is it possible to ensure the __exit__() method is called even if there is an exception in __enter__()?
>>> class TstContx(object):
... def __enter__(self):
... raise Exception('Oops in _...
Cognizant asked 25/10, 2012 at 18:25
9
Solved
I am struggling to make a piece of code that allows to measure time spent within a "with" statement and assigns the time measured (a float) to the variable provided in the "with" statement.
import...
Fluoro asked 29/11, 2015 at 19:29
7
Solved
What is a clean way to create a multi-line with in python? I want to open up several files inside a single with, but it's far enough to the right that I want it on multiple lines. Like this:
class...
Acclimate asked 24/6, 2015 at 23:49
2
Solved
Im using PL/SQL. I am trying to have a for loop right after I define my temporary tables in the with clause. However, Im getting an error to have a SELECT query first.
For instance
WITH TMP1 AS (...
Livonia asked 30/5, 2016 at 4:47
9
Solved
I am defining a context manager class and I would like to be able to skip the block of code without raising an exception if certain conditions are met during instantiation. For example,
class My_C...
Hydrogeology asked 26/9, 2012 at 3:28
5
Below is an example of my my_create method, and an example of that method in use.
@contextmanager
def my_create(**attributes):
obj = MyObject(**attributes)
yield obj
obj.save()
with my_create...
Cholula asked 2/2, 2018 at 22:28
8
Solved
Instead of this:
file = open(f)
do_something(file)
file.close()
it's better to use this:
with open(f) as file:
do_something(file)
What if I have something like this?
if f is not None:
file = op...
Ophthalmitis asked 28/8, 2012 at 22:7
17
I've heard many programmers, particularly Delphi programmers scorn the use of 'with'.
I thought it made programs run faster (only one reference to parent object) and that it was easier to read th...
Twoup asked 16/9, 2008 at 11:35
3
Solved
After reading this : How do I mock an open used in a with statement (using the Mock framework in Python)?
I'm able to mock the open function in python using :
with patch(open_name, create=True) a...
Ouellette asked 19/2, 2012 at 12:26
3
Solved
New to unittest and Python in general, came across example in a tutorial introduction to unit testing wherein a with statement is used to catch a ValueError.
The script being tested (invoice_calc...
Unreel asked 16/12, 2015 at 23:31
3
Solved
Are these two statements equivalent?
with A() as a, B() as b:
# do something
with A() as a:
with B() as b:
# do something
I ask because both a and b alter global variables (tensorflow here) ...
Elsey asked 31/3, 2017 at 1:33
10
Solved
Is there a way to begin a block of code with a with statement, but conditionally?
Something like:
if needs_with():
with get_stuff() as gs:
# do nearly the same large block of stuff,
# involving...
Markham asked 6/1, 2015 at 16:36
6
Solved
I've been trying to find RAII in Python.
Resource Allocation Is Initialization is a pattern in C++ whereby
an object is initialized as it is created. If it fails, then it throws
an exception. In th...
Aborigine asked 21/2, 2011 at 20:50
1
cx_Oracle contains __enter__ and __exit__ on Connection objects, but not on Cursor objects. Thus, I use this everywhere to wrap cursors :
class CursorWrapper(object):
def __init__(self, connection...
Frech asked 11/12, 2015 at 16:15
4
Solved
I have some legacy code with a legacy function that takes a filename as an argument and processes the file contents. A working facsimile of the code is below.
What I want to do is not have to writ...
Marquittamarr asked 9/8, 2012 at 22:2
4
Solved
The following is listed as example in pymysql:
conn = pymysql.connect(...)
with conn.cursor() as cursor:
cursor.execute(...)
...
conn.close()
Can I use the following instead, or will this leav...
Drachm asked 3/7, 2015 at 22:2
6
Solved
It turns out that "with" is a funny word to search for on the internet.
Does anyone knows what the deal is with nesting with statements in python?
I've been tracking down a very slippery bug in a ...
Pare asked 2/1, 2010 at 2:18
3
I am using a Python 3 sequence like this:
lock = threading.Lock()
res = lock.acquire(timeout=10)
if res:
# do something ....
lock.release()
else:
# do something else ...
I would prefer to use...
Synonym asked 24/5, 2013 at 17:0
4
I always open and write into files using with statement:
with open('file_path', 'w') as handle:
print >>handle, my_stuff
However, there is one instance where I need to be able to be more ...
Carbonyl asked 8/3, 2014 at 3:9
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