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Why exactly is eval evil?
I know that Lisp and Scheme programmers usually say that eval should be avoided unless strictly necessary. I’ve seen the same recommendation for several programming languages, but I’ve not yet seen a list of clear arguments against the use of eval . Where can I find an account of the potentia...
Xml Namespace breaking my xpath! [duplicate]
...t element has been defined with a default namespace and this is adopted by all elements inside.
You therefore need to ignore the element namespace like so:
/*[local-name()='List']/*[local-name()='Fields]/*[local-name()='Field]
but this means that the xpath will pick up any other element with Lis...
How to randomly select an item from a list?
...
Use random.choice()
import random
foo = ['a', 'b', 'c', 'd', 'e']
print(random.choice(foo))
For cryptographically secure random choices (e.g. for generating a passphrase from a wordlist) use secrets.choice()
import secrets
foo = ['battery', 'correct', 'ho...
Why does ++[[]][+[]]+[+[]] return the string “10”?
...array ([]). Due to references it's wrong to say [[]][0] === [], but let's call the inner array A to avoid the wrong notation.
++ before its operand means “increment by one and return the incremented result”. So ++[[]][0] is equivalent to Number(A) + 1 (or +A + 1).
Again, we can simplify the me...
Constructor function vs Factory functions
...function is used with the new keyword (which causes JavaScript to automatically create a new object, set this within the function to that object, and return the object):
var objFromConstructor = new ConstructorFunction();
A factory function is called like a "regular" function:
var objFromFactory...
git diff between cloned and original remote repository
I have cloned a github repository and made no changes locally. Github repository moved forward with commits on the same branch.
...
Correct way to detach from a container without stopping it
...aseimage-docker/#intro)
If you want a container that run in detached mode all the time, i suggest you use
docker run -d foo
With an ssh server on the container. (easiest way is to follow the dockerizing openssh tutorial https://docs.docker.com/engine/examples/running_ssh_service/)
Or you can ju...
Shell script - remove first and last quote (") from a variable
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@jsears Huh? This specifically trims one from the start if there is one, and one from the end if there is one. If you don't want to remove unless both are present; yes, a single sed regex could be used, or the variable substitution could be wrapped i...
how to specify local modules as npm package dependencies
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npm install now supports this
npm install --save ../path/to/mymodule
For this to work mymodule must be configured as a module with its own package.json. See Creating NodeJS modules.
As of npm 2.0, local dependencies are supported...
Create instance of generic type in Java?
...type information is available via reflection. e.g.,
public abstract class Foo<E> {
public E instance;
public Foo() throws Exception {
instance = ((Class)((ParameterizedType)this.getClass().
getGenericSuperclass()).getActualTypeArguments()[0]).newInstance();
...
}
}
...