You need to pass in a pointer to a pointer if you want to do this. void barPush(BarList ** list,Bar * bar) { if (list == NULL) return; // need to pass in the pointer to your pointer to your list. // if there is no move to add, then we are done if (bar … Read more
There is no pythonic way of doing this. Python provides very few facilities for enforcing things such as private or read-only data. The pythonic philosophy is that “we’re all consenting adults”: in this case this means that “the function shouldn’t change the data” is part of the spec but not enforced in the code. If … Read more
When in doubt, pass by value. Now, you should only rarely be in doubt. Often values are expensive to pass and give little benefit. Sometimes you actually want a reference to a possibly mutating value stored elsewhere. Often, in generic code, you don’t know if copying is an expensive operation, so you err on the … Read more
Arguments are passed by value, unless the function signature specifies otherwise: in void foo(type arg), arg is passed by value regardless of whether type is a simple type, a pointer type or a class type, in void foo(type& arg), arg is passed by reference. In case of arrays, the value that is passed is a … Read more
Python passes references-to-objects by value. Python passes references-to-objects by value (like Java), and everything in Python is an object. This sounds simple, but then you will notice that some data types seem to exhibit pass-by-value characteristics, while others seem to act like pass-by-reference… what’s the deal? It is important to understand mutable and immutable objects. … Read more
Call-by-value The R Language Definition says this (in section 4.3.3 Argument Evaluation) The semantics of invoking a function in R argument are call-by-value. In general, supplied arguments behave as if they are local variables initialized with the value supplied and the name of the corresponding formal argument. Changing the value of a supplied argument within … Read more
The const qualifier prevents code inside the function from modifying the parameter itself. When a function is larger than trivial size, such an assurance helps you to quickly read and understand a function. If you know that the value of side won’t change, then you don’t have to worry about keeping track of its value … Read more
Everything in Go is passed by value, slices too. But a slice value is a header, describing a contiguous section of a backing array, and a slice value only contains a pointer to the array where the elements are actually stored. The slice value does not include its elements (unlike arrays). So when you pass … Read more
I found myself disagreeing with the highest-voted answer, so I went looking for expert opinons and here they are. From http://channel9.msdn.com/Shows/Going+Deep/C-and-Beyond-2011-Scott-Andrei-and-Herb-Ask-Us-Anything Herb Sutter: “when you pass shared_ptrs, copies are expensive” Scott Meyers: “There’s nothing special about shared_ptr when it comes to whether you pass it by value, or pass it by reference. Use exactly the … Read more
In modern browsers, you can use the let or const keywords to create a block-scoped variable: for (let i = 0; i < results.length; i++) { let marker = results[i]; google.maps.event.addListener(marker, ‘click’, () => change_selection(i)); } In older browsers, you need to create a separate scope that saves the variable in its current state by … Read more