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What's the difference between eval, exec, and compile?
... call last):
File "<stdin>", line 1, in <module>
File "<string>", line 1
a = 47
^
SyntaxError: invalid syntax
The compile in 'exec' mode compiles any number of statements into a bytecode that implicitly always returns None, whereas in 'eval' mode it compiles a sin...
PDO's query vs execute
...are on the : calories is that kind of the equivalent of mysql_real_escape_string() to stop injections or do you need more than just $sth->bindParam(':calories', $calories); to heighten security?
– Dan
Jan 5 '12 at 12:52
...
How to count the number of set bits in a 32-bit integer?
...bit elements in a 64-bit integer with a 0x0101010101010101 multiplier, and extract the high byte with >>56. So it doesn't take any extra steps, just wider constants. This is what GCC uses for __builtin_popcountll on x86 systems when the hardware popcnt instruction isn't enabled. If you can ...
Using -performSelector: vs. just calling the method
...s explained in a previous answer. For example
SEL method = NSSelectorFromString([NSString stringWithFormat:@"doSomethingWithMy%@:", @"Age");
[object performSelector:method];
The other use, is to asynchronously dispatch a message to object, that will be executed later on the current runloop. For ...
Difference: std::runtime_error vs std::exception()
...
std::runtime_error on the other hand has valid constructors that accept a string as a message. When what() is called a const char pointer is returned that points at a C string that has the same string as was passed into the constructor.
try
{
if (badThingHappened)
{
throw std::run...
How to find out element position in slice?
... }
}
return -1
}
And usage:
xs := []int{2, 4, 6, 8}
ys := []string{"C", "B", "K", "A"}
fmt.Println(
SliceIndex(len(xs), func(i int) bool { return xs[i] == 5 }),
SliceIndex(len(xs), func(i int) bool { return xs[i] == 6 }),
SliceIndex(len(ys), func(i int) bool { return ys[i]...
Calling constructor from other constructor in same class
... the constructor to do 'constructor chaining'
public Test( bool a, int b, string c )
: this( a, b )
{
this.m_C = c;
}
public Test( bool a, int b, float d )
: this( a, b )
{
this.m_D = d;
}
private Test( bool a, int b )
{
this.m_A = a;
this.m_B = b;
}
Source Courtesy of csh...
How do I look inside a Python object?
...
the best way to see object and its contents in a string
– Peter Krauss
Dec 28 '19 at 21:57
T...
How to remove an item from an array in AngularJS scope?
...tion above - being - delete({{$index}}) with the {{ }} otherwise I got the string $index - BUT I have something wrong because it never calls that method. It does when I remove any mention of the index like delete() but that doesn't really help.
– mikemil
Oct 2...
Rails migrations: self.up and self.down versus change
...d only delete this column on down
def up
add_column :users, :location, :string
User.update_all(location: 'Minsk')
end
def down
remove_column :users, :location
end
But:
You had to avoid using change method which allows to save some time. For example, if you didn’t need to update column v...