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How to set a default value for a datetime column to record creation time in a migration?
...
You can add a function in a model like this:
before_create :set_foo_to_now
def set_foo_to_now
self.foo = Time.now
end
So that the model will set the current time in the model.
You can also place some sql code in the migration for setting the default value at the database level,...
New self vs. new static
...uated at compile time and must not depend on run-time information.
class Foo {
public $name = static::class;
}
$Foo = new Foo;
echo $Foo->name; // Fatal error
Using self::
class Foo {
public $name = self::class;
}
$Foo = new Foo;
echo $Foo->name; // Foo
Please note that ...
Passing a String by Reference in Java?
...ew StringBuilder ();
void fillString(StringBuilder zText) { zText.append ("foo"); }
Create a container class and pass an instance of the container to your method:
public class Container { public String data; }
void fillString(Container c) { c.data += "foo"; }
Create an array:
new String[] zText ...
Is there a performance difference between i++ and ++i in C++?
...e of the operator++ functions. Here's a standard pair of these functions:
Foo& Foo::operator++() // called for ++i
{
this->data += 1;
return *this;
}
Foo Foo::operator++(int ignored_dummy_value) // called for i++
{
Foo tmp(*this); // variable "tmp" cannot be optimized away...
Git: “Corrupt loose object”
...Execute these commands from the parent directory above your repo (replace 'foo' with the name of your project folder):
Create a backup of the corrupt directory:
cp -R foo foo-backup
Make a new clone of the remote repository to a new directory:
git clone git@www.mydomain.de:foo foo-newclone
Delete ...
How to make clang compile to llvm IR
...
Given some C/C++ file foo.c:
> clang -S -emit-llvm foo.c
Produces foo.ll which is an LLVM IR file.
The -emit-llvm option can also be passed to the compiler front-end directly, and not the driver by means of -cc1:
> clang -cc1 foo.c -emi...
Getting SyntaxError for print with keyword argument end=' '
... isn't available in Python 2.x because print is still a statement.
print("foo" % bar, end=" ")
in Python 2.x is identical to
print ("foo" % bar, end=" ")
or
print "foo" % bar, end=" "
i.e. as a call to print with a tuple as argument.
That's obviously bad syntax (literals don't take keyword...
Remove NA values from a vector
... I remove NA values from a vector?
Here it is:
Assume you have a vector foo as follows:
foo = c(1:10, NA, 20:30)
running length(foo) gives 22.
nona_foo = foo[!is.na(foo)]
length(nona_foo) is 21, because the NA values have been removed.
Remember is.na(foo) returns a boolean matrix, so ind...
Mongoose and multiple database in single node.js project
...roject, one mongoose installation and one mongoose instance.
-app_root/
--foo_app/
---db_access.js
---foo_db_connect.js
---node_modules/
----mongoose/
--bar_app/
---db_access.js
---bar_db_connect.js
---node_modules/
----mongoose/
In foo_db_connect.js
var mongoose = require('mongoose');
mongoose....
“X does not name a type” error in C++
...efined is called an incomplete type.
Consider the simpler example:
struct foo; // foo is *declared* to be a struct, but that struct is not yet defined
struct bar
{
// this is okay, it's just a pointer;
// we can point to something without knowing how that something is defined
foo* fp; ...