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How do I provide custom cast support for my class?
...ou want users to have to cast it or whether you want it to happen automagically. Generally, one direction will always work, that's where you use implicit, and the other direction can sometimes fail, that's where you use explicit.
The syntax is like this:
public static implicit operator dbInt64(Byt...
sizeof single struct member in C
... char text[member_size(Parent, text)];
int used;
} Child;
I'm actually a bit surprised that sizeof((type *)0)->member) is even allowed as a constant expression. Cool stuff.
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impr...
Installing python module within code
I need to install a package from PyPi straight within my script.
Maybe there's some module or distutils ( distribute , pip etc.) feature which allows me to just execute something like pypi.install('requests') and requests will be installed into my virtualenv.
...
Which SQL query is faster? Filter on Join criteria or Where clause?
...
Performance-wise, they are the same (and produce the same plans)
Logically, you should make the operation that still has sense if you replace INNER JOIN with a LEFT JOIN.
In your very case this will look like this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = ...
Python extract pattern matches
...h a standard python REPL, the last result is stored in a special variable called _. It isn't valid outside anywhere else.
– UltraInstinct
Mar 13 '19 at 2:25
...
Check if all elements in a list are identical
... = next(iterator)
except StopIteration:
return True
return all(first == rest for rest in iterator)
One-liner:
def checkEqual2(iterator):
return len(set(iterator)) <= 1
Also one-liner:
def checkEqual3(lst):
return lst[1:] == lst[:-1]
The difference between the 3 versi...
Installing older version of R package
...
To install an older version of a package from source (within R):
packageurl <- "http://cran.r-project.org/src/contrib/Archive/ggplot2/ggplot2_0.9.1.tar.gz"
install.packages(packageurl, repos=NULL, type="source")
If this doesn'...
How do I get indices of N maximum values in a NumPy array?
...t been able to find one.
If this solution turns out to be too slow (especially for small n), it may be worth looking at coding something up in Cython.
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Disable migrations when running unit tests in Django 1.7
... syncdb did in 1.6. I defined a new settings module just for unit
tests called "settings_test.py", which imports * from the main
settings module and adds this line:
MIGRATION_MODULES = {"myapp": "myapp.migrations_not_used_in_tests"}
Then I run tests like this:
DJANGO_SETTINGS_MODU...
PHP: Convert any string to UTF-8 without knowing the original character set, or at least try
I have an application that deals with clients from all over the world, and, naturally, I want everything going into my databases to be UTF-8 encoded.
...