one would prefer default over server default for one of four reasons: you’d like to run a Python function, not a SQL function, for the default (or a SQL expression that needs some per-INSERT Python state also). the default is part of a primary key column. the ORM can’t load a row back without the … Read more
To pass a named argument to a vararg parameter, use the spread operator: complicated(numbers = *intArrayOf(1, 2, 3, 4, 5))
Not so hard: A x; A * p = new A; These two are default initialization. Since you don’t have a user-defined constructor, this just means that all members are default-initialized. Default-initializing a fundamental type like int means “no initialization”. Next: A * p = new A(); This is value initialization. (I don’t think there … Read more
This statement: <property file=”${user.home}/build.properties”/> Reads a property file(i.e. all properties in that file), and does not set the property named file. This would be correct. You first set a property and then echo it: <property name=”file” value=”${user.home}/build.properties”/> <echo message=”${file}” />
According to MSDN, to use the default parameter you should pass Type.Missing. If your constructor has three optional arguments then instead of passing an empty object array you’d pass a three element object array where each element’s value is Type.Missing, e.g. type.GetParameterlessConstructor() .Invoke(BindingFlags.OptionalParamBinding | BindingFlags.InvokeMethod | BindingFlags.CreateInstance, null, new object[] { Type.Missing, Type.Missing, Type.Missing }, … Read more
Python 3: inp = int(input(“Enter the inputs : “) or “42”) Python 2: inp = int(raw_input(“Enter the inputs : “) or “42”) How does it work? If nothing was entered then input/raw_input returns empty string. Empty string in Python is False, bool(“”) -> False. Operator or returns first truthy value, which in this case is … Read more
If myFunc(variable) is executed before the textarea is rendered to the page, you will get the null exception error. <html> <head> <title>index</title> <script type=”text/javascript”> function myFunc(variable) { var s = document.getElementById(variable); s.value = “new value”; } myFunc(“id1″); </script> </head> <body> <textarea id=”id1”></textarea> </body> </html> <!– Error message: Cannot set property ‘value’ of null –> So, … Read more
Usually, a Python dictionary throws a KeyError if you try to get an item with a key that is not currently in the dictionary. The defaultdict in contrast will simply create any items that you try to access (provided of course they do not exist yet). To create such a “default” item, it calls the … Read more
The best method is to use collections.defaultdict with a list default: from collections import defaultdict dct = defaultdict(list) Then just use: dct[key].append(some_value) and the dictionary will create a new list for you if the key is not yet in the mapping. collections.defaultdict is a subclass of dict and otherwise behaves just like a normal dict … Read more
The simple solution is to just implement the default arguments in __post_init__() only! @dataclass class Specs2: a: str b: str c: str def __post_init__(self): if self.b is None: self.b = ‘Bravo’ if self.c is None: self.c=”Charlie” (Code is not tested. If I got some detail wrong, it wouldn’t be the first time)