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Batch script loop
...e
for /l %%x in (1, 1, 100) do echo %%x
(which is one of the things I really really hate about windows scripting)
If you have multiple commands for each iteration of the loop, do this:
for /l %x in (1, 1, 100) do (
echo %x
copy %x.txt z:\whatever\etc
)
or in a batch file
for /l %%x in ...
Realistic usage of the C99 'restrict' keyword?
...aw it mentioned. I read a brief description, stating that it would be basically a promise from the programmer that the pointer won't be used to point somewhere else.
...
Understanding __get__ and __set__ and Python descriptors
...th the Temperature class). For example:
temp=Temperature()
temp.celsius #calls celsius.__get__
Accessing the property you assigned the descriptor to (celsius in the above example) calls the appropriate descriptor method.
instance in __get__ is the instance of the class (so above, __get__ would r...
Python Infinity - Any caveats?
...involving inf:
>>> 0 * float("inf")
nan
Note that you will normally not get an inf value through usual arithmetic calculations:
>>> 2.0**2
4.0
>>> _**2
16.0
>>> _**2
256.0
>>> _**2
65536.0
>>> _**2
4294967296.0
>>> _**2
1.84467440737...
What is a callback function?
What is a callback function?
21 Answers
21
...
psql: FATAL: role “postgres” does not exist
...
NOTE: If you installed postgres using homebrew, see the comment from @user3402754 below.
Note that the error message does NOT talk about a missing database, it talks about a missing role. Later in the login process it might also s...
std::unique_ptr with an incomplete type won't compile
...
I find your first solution (adding the foo destructor) allows the class declaration itself to compile, but declaring an object of that type anywhere results in the original error ("invalid application of 'sizeof'...").
– Jeff Trull
Sep 30 '1...
How does Bluebird's util.toFastProperties function make an object's properties “fast”?
... eval("o" + o); // ensure no dead code elimination
}
Sans one or two small optimizations - all the below is still valid.
Let's first discuss what it does and why that's faster and then why it works.
What it does
The V8 engine uses two object representations:
Dictionary mode - in which object ar...
How to redirect output with subprocess in Python?
...lbeit still available in Python 3.
Use os.system:
os.system(my_cmd)
If you really want to use subprocess, here's the solution (mostly lifted from the documentation for subprocess):
p = subprocess.Popen(my_cmd, shell=True)
os.waitpid(p.pid, 0)
OTOH, you can avoid system calls entirely:
impo...
Python: try statement in a single line
...ther dynamic languages. The safer way (and the prevailing style) is to set all variables to something. If they might not get set, set them to None first (or 0 or '' or something if it is more applicable.)
If you do assign all the names you are interested in first, you do have options.
The best...