default-value

问题 It seems like ipywidgets.interactive tries to make every imput after the function to be a widget. In the following example, I get two widgets, one for age and one for name : import ipywidgets def greetings(age, name='John'): print(f'{name} is {age} years old') ipywidgets.interactive(greetings, age = widgets.IntSlider(), name = "Bob") My expectation was, that I only get one widget for age , since it is of type ipywidgets.widgets.widget_int.IntSlider whereas "Bob" is of type str (where I don't

问题 I'm a bit confused about how scope & variable assignment within a function seems to change when assigning a default parameter value for that function. For example, when this function has a default value assigned to parameter i , the output array variable appears to be block-scoped when inspected with Chrome Dev Console,: function steps(n, i = 40) { var output = [n]; } steps(10, 20); However, by removing the default parameter value for i , the output array variable is scoped locally: function

问题 Assuming the template function template<typename T> T foo(){ // ... // Error occured if(error) return 0; // ... } which should return 0 , 0.0f , nullptr , ... depending on the type T , when an error occured. How to get the 0 of a unknown template type? in C# you can write default(T) to do this. How to perform this in C++? 回答1: You can use value initialization like return T(); or return T{}; (since C++11), or just return {}; (see list initialization (since C++11)) to return the default value

问题 Assuming the template function template<typename T> T foo(){ // ... // Error occured if(error) return 0; // ... } which should return 0 , 0.0f , nullptr , ... depending on the type T , when an error occured. How to get the 0 of a unknown template type? in C# you can write default(T) to do this. How to perform this in C++? 回答1: You can use value initialization like return T(); or return T{}; (since C++11), or just return {}; (see list initialization (since C++11)) to return the default value

来源： https://stackoverflow.com/questions/49343475/entity-framework-6-code-first-default-value-overriding-the-migrationcodegenerato

问题 is it possible to use a function as my React Component's state ? example code here: // typescript type OoopsFunction = () => void; export function App() { const [ooops, setOoops] = React.useState<OoopsFunction>( () => console.log('default ooops') ); return ( <div> <div onClick={ ooops }> Show Ooops </div> <div onClick={() => { setOoops(() => console.log('other ooops')) }}> change oops </div> </div> ) } but it doesn't works ... the defaultOoops will be invoked at very beginning, and when

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because

问题 We know that the javascript logical operator || produces the value of its first operand if the first operand is true . Otherwise, it produces the value of the second operand. So in this example: <script language="javascript"> function test (value){ this.value = value || "(value not given)"; } </script> if the parameter value passed to the function is treated as false like the integer 0 or the empty string "" then this.value will be set to ( value not given) which is not true correct (because