idioms

I run into this case a lot of times when doing simple text processing and print statements where I am looping over a collection and I want to special case the last element (for example every normal element will be comma separated except for the last case). Is there some best practice idiom or elegant form that doesn't require duplicating code or shoving in an if, else in the loop. For example I have a list of strings that I want to print in a comma separated list. (the do while solution already assumes the list has 2 or more elements otherwise it'd be just as bad as the more correct for loop

What is the best (idiomatic) way to concatenate Strings in Groovy? Option 1: calculateAccountNumber(bank, branch, checkDigit, account) { bank + branch + checkDigit + account } Option 2: calculateAccountNumber(bank, branch, checkDigit, account) { "$bank$branch$checkDigit$account" } I've founded an interesting point about this topic in the old Groovy website: Things you can do but better leave undone. As in Java, you can concatenate Strings with the "+" symbol. But Java only needs that one of the two items of a "+" expression to be a String, no matter if it's in the first place or in the last

Suppose we have template <unsigned N> foo() { /* ... */ } defined. Now, I want to implement do_foo(unsigned n); which calls the corresponding variant of foo() . This is not merely a synthetic example - this does actually happen in real life (of course, not necessarily with void-to-void functions and just one template parameter, but I'm simplfying. Of course, in C++, we can't have the following: do_foo(unsigned n) { foo<n>(); } and what I do right now is do_foo(unsigned n) { switch(n) { case n_1: foo<n_1>(); break; case n_2: foo<n_2>(); break; /* ... */ case n_k: foo<n_k>(); break; } } when I

For instance, say I wanted a function to escape a string for use in HTML (as in Django's escape filter ): def escape(string): """ Returns the given string with ampersands, quotes and angle brackets encoded. """ return string.replace('&', '&').replace('<', '<').replace('>', '>').replace("'", ''').replace('"', '"') This works, but it gets ugly quickly and appears to have poor algorithmic performance (in this example, the string is repeatedly traversed 5 times). What would be better is something like this: def escape(string): """ Returns the given string with ampersands, quotes and angle brackets

In C++ an interface can be implemented by a class with all its methods pure virtual. Such a class could be part of a library to describe what methods an object should implement to be able to work with other classes in the library: class Lib::IFoo { public: virtual void method() = 0; }; : class Lib::Bar { public: void stuff( Lib::IFoo & ); }; Now I want to to use class Lib::Bar, so I have to implement the IFoo interface. For my purposes I need a whole of related classes so I would like to work with a base class that guarantees common behavior using the NVI idiom: class FooBase : public IFoo //