I guess you need something like this: const MySelect = props => ( <Select {…props} value = { props.options.filter(option => option.label === ‘Some label’) } onChange = {value => props.input.onChange(value)} onBlur={() => props.input.onBlur(props.input.value)} options={props.options} placeholder={props.placeholder} /> );
In the Python spirit of “ask for forgiveness, not permission”, here’s one way: try: b = a[4] except IndexError: b = ‘sss’
One possible idea is to write separate constructor function //Something is the structure we work with type Something struct { Text string DefaultText string } // NewSomething create new instance of Something func NewSomething(text string) Something { something := Something{} something.Text = text something.DefaultText = “default text” return something }
Python 3.7 Use the defaults parameter. >>> from collections import namedtuple >>> fields = (‘val’, ‘left’, ‘right’) >>> Node = namedtuple(‘Node’, fields, defaults=(None,) * len(fields)) >>> Node() Node(val=None, left=None, right=None) Or better yet, use the new dataclasses library, which is much nicer than namedtuple. >>> from dataclasses import dataclass >>> from typing import Any >>> … Read more
I’d personally be very hesitant to change the default behavior of any commonly used functions — especially base R functions. For one thing, it will immediately decrease the portability of any scripts or code snippets in which you use the redefined functions. Worse, other R users reading your scripts will likely be either: (a) unaware … Read more
You can work around this very easily by changing your signature. void Foo(TimeSpan? span = null) { if (span == null) { span = TimeSpan.FromSeconds(2); } … } I should elaborate – the reason those expressions in your example are not compile-time constants is because at compile time, the compiler can’t simply execute TimeSpan.FromSeconds(2.0) and … Read more
If you want a real database default value, use columnDefinition: @Column(name = “myColumn”, nullable = false, columnDefinition = “int default 100”) Notice that the string in columnDefinition is database dependent. Also if you choose this option, you have to use dynamic-insert, so Hibernate doesn’t include columns with null values on insert. Otherwise talking about default … Read more
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
There are no differences between structs and classes in this regard in C++. They all are called just class types. Members of class types have no default values in general case. In order to for a class member to get a deterministic value it has to be initialized, which can be done by Default constructor … Read more
Mutable default arguments don’t generally do what you want. Instead, try this: class Node: def __init__(self, wordList=None, adjacencyList=None): if wordList is None: self.wordList = [] else: self.wordList = wordList if adjacencyList is None: self.adjacencyList = [] else: self.adjacencyList = adjacencyList