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RAII and smart pointers in C++
.... This has two drawbacks - firstly, wherever we use File, we will have to called File::close() - if we forget to do this, we're holding onto the file longer than we need to. The second problem is what if an exception is thrown before we close the file?
Java solves the second problem using a finally...
Get the data received in a Flask request
.... In most common cases request.data will be empty because it's used as a fallback:
request.data Contains the incoming request data as string in case it came with a mimetype Flask does not handle.
request.args: the key/value pairs in the URL query string
request.form: the key/value pairs in t...
Accessing members of items in a JSONArray with Java
I'm just getting started with using json with java. I'm not sure how to access string values within a JSONArray. For instance, my json looks like this:
...
error LNK2019: 无法解析的外部符号_socket，该符号在函数 中被引用 - c++1...
1>NetClient.obj : error LNK2019: 无法解析的外部符号 _closesocket@4，该符号在函数 _main 中被引用
1>NetClient.obj : error LNK2019: 无法解析的外部符号 _inet_ntoa@4，该符号在函数 _main 中被引用
1>NetClient.obj : error LNK2019: 无法解析的外部符...
The way to check a HDFS directory's size?
...
Prior to 0.20.203, and officially deprecated in 2.6.0:
hadoop fs -dus [directory]
Since 0.20.203 (dead link) 1.0.4 and still compatible through 2.6.0:
hdfs dfs -du [-s] [-h] URI [URI …]
You can also run hadoop fs -help for more info and specifics...
How to keep a Python script output window open?
...w.
Add code to wait at the end of your script. For Python2, adding ...
raw_input()
... at the end of the script makes it wait for the Enter key. That method is annoying because you have to modify the script, and have to remember removing it when you're done. Specially annoying when testing other ...
How to set default values in Rails?
...
"Correct" is a dangerous word in Ruby. There's usually more than one way to do anything. If you know you'll always want that default value for that column on that table, setting them in a DB migration file is the easiest way:
class SetDefault < ActiveRecord::Migration
...
Android - Pulling SQlite database android device
... pro tip: this backup stuff won't work if the app's manifest shows android:allowBackup="false"
– Someone Somewhere
May 27 '14 at 1:23
9
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How to count the number of files in a directory using Python
...
For all kind of files, subdirectories included:
import os
list = os.listdir(dir) # dir is your directory path
number_files = len(list)
print number_files
Only files (avoiding subdirectories):
import os
onlyfiles = next(os.w...
python design patterns [closed]
...for their existence.
It's nothing more than
class Null(object):
def __init__(self, *args, **kwargs):
"Ignore parameters."
return None
def __call__(self, *args, **kwargs):
"Ignore method calls."
return self
def __getattr__(self, mname):
"Ignore...