To populate the column during insert, use a DEFAULT value: CREATE TABLE users ( id serial not null, firstname varchar(100), middlename varchar(100), lastname varchar(100), email varchar(200), timestamp timestamp default current_timestamp ) Note that the value for that column can explicitly be overwritten by supplying a value in the INSERT statement. If you want to prevent … Read more
In your example, your integer is boxed and therefore your T is going to be object, and the default of object is null, so that’s not valuable to you. If the object is a value type, you could get an instance of it (which would be the default) to use as a comparison. Something like: … Read more
Your code (simplified): struct X { int mem; void f(int param = mem); //ERROR }; You want to use a non-static member data as default value for a parameter of a member function. The first question which comes to mind is this : which specific instance of the class the default value mem belongs to? … Read more
As documented under Data Type Default Values: The DEFAULT value clause in a data type specification indicates a default value for a column. With one exception, the default value must be a constant; it cannot be a function or an expression. This means, for example, that you cannot set the default for a date column … Read more
In my apps, I have a seperate settings.py file. In that file I have a get() function that does a look up in the projects settings.py file and if not found returns the default value. from django.conf import settings def get(key, default): return getattr(settings, key, default) APPLES = get(‘APPLES’, 1) Then where I need to … Read more
I have never seen this behavior before but I’m pretty sure this is what the init step is for when allocation an object, that is setting variables and initializing the object. -(id)init { if (self = [super init]) { self.someProperty = 10; } return self; } And the call it like this: MyClass* test = … Read more
It’s 0. It can’t be null, as null isn’t a valid int value. From section 7.6.10.4 of the C# 5 specification: All elements of the new array instance are initialized to their default values (ยง5.2). And from section 5.2: The default value of a variable depends on the type of the variable and is determined … Read more
It is better to use Spring EL in such way <property name=”password” value=”${email.password:#{null}}”/> it checks whether email.password is specified and sets it to null (not “null” String) otherwise
Only pointers can be null. CGRect is a struct – it represents a contiguous block of memory. The only way to tell if it has been set it to check its contents. Apple does provide a constant CGRectNull. You could set your variable to this and use the CGRectIsNull function to determine if it has … Read more
As @Ignacio says, you can’t do this. In your latter example, you might have a situation where None is a valid value for arg2. If this is the case, you can use a sentinel value: sentinel = object() def myfunc(arg1, arg2=sentinel): if arg2 is sentinel: arg2 = arg1 print (arg1, arg2) myfunc(“foo”) # Prints ‘foo … Read more