I found another way you can do it was to have the source and property strongly typed and explicitly infer the input for the lambda. Not sure if that is correct terminology but here is the result. public static RouteValueDictionary GetInfo<T,P>(this HtmlHelper html, Expression<Func<T, P>> action) where T : class { var expression = (MemberExpression)action.Body; … Read more
A lambda can only be converted to a function pointer if it does not capture, from the draft C++11 standard section 5.1.2 [expr.prim.lambda] says (emphasis mine): The closure type for a lambda-expression with no lambda-capture has a public non-virtual non-explicit const conversion function to pointer to function having the same parameter and return types as … Read more
Are you talking about lambda expressions? Like lambda x: x**2 + 2*x – 5 Those things are actually quite useful. Python supports a style of programming called functional programming where you can pass functions to other functions to do stuff. Example: mult3 = filter(lambda x: x % 3 == 0, [1, 2, 3, 4, 5, … Read more
A while ago our team migrated all its code (a mid-sized AngularJS app) to JavaScript compiled using Traceur Babel. I’m now using the following rule of thumb for functions in ES6 and beyond: Use function in the global scope and for Object.prototype properties. Use class for object constructors. Use => everywhere else. Why use arrow … Read more
you may force the capture of a variable using an argument with a default value: >>> for i in [0,1,2,3]: … adders[i]=lambda a,i=i: i+a # note the dummy parameter with a default value … >>> print( adders[1](3) ) 4 the idea is to declare a parameter (cleverly named i) and give it a default value … Read more
The problem C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function. #include <algorithm> #include <vector> namespace { struct f { void operator()(int) { // do something … Read more