Idiomatic means following the conventions of the language. You want to find the easiest and most common ways of accomplishing a task rather than porting your knowledge from a different language. non-idiomatic python using a loop with append: mylist = [1, 2, 3, 4] newlist = [] for i in mylist: newlist.append(i * 2) idiomatic … Read more
My favorite way to do it: def pairwise(t): it = iter(t) return zip(it,it) # for “pairs” of any length def chunkwise(t, size=2): it = iter(t) return zip(*[it]*size) When you want to pair all elements you obviously might need a fillvalue: from itertools import izip_longest def blockwise(t, size=2, fillvalue=None): it = iter(t) return izip_longest(*[it]*size, fillvalue=fillvalue) With … Read more
I think you are looking for instance_of?. is_a? and kind_of? will return true for instances from derived classes. class X < String end foo = X.new foo.is_a? String # true foo.kind_of? String # true foo.instance_of? String # false foo.instance_of? X # true
Basically it’s the pattern where you write a method to do things which are always required, e.g. resource allocation and clean-up, and make the caller pass in “what we want to do with the resource”. For example: public interface InputStreamAction { void useStream(InputStream stream) throws IOException; } // Somewhere else public void executeWithFile(String filename, InputStreamAction … Read more
This is now touched on in the second edition of The Rust Programming Language. However, let’s dive in a bit in addition. Let us start with a simpler example. When is it appropriate to use a trait method? There are multiple ways to provide late binding: trait MyTrait { fn hello_word(&self) -> String; } Or: … Read more
Probably the shortest would be str(s or ”) Because None is False, and “x or y” returns y if x is false. See Boolean Operators for a detailed explanation. It’s short, but not very explicit.
This question provides an idiom. You use one of the dicts as keyword arguments to the dict() constructor: dict(y, **x) Duplicates are resolved in favor of the value in x; for example dict({‘a’ : ‘y[a]’}, **{‘a’, ‘x[a]’}) == {‘a’ : ‘x[a]’}
A good rule of thumb is for anything that you need to compare in the loop condition against something that is naturally a std::size_t itself. std::size_t is the type of any sizeof expression and as is guaranteed to be able to express the maximum size of any object (including any array) in C++. By extension … Read more
Most of the times it is easier (and cheaper) to make the first iteration the special case instead of the last one: first = True for data in data_list: if first: first = False else: between_items() item() This will work for any iterable, even for those that have no len(): file = open(‘/path/to/file’) for line … Read more
To reverse an int array, you swap items up until you reach the midpoint, like this: for(int i = 0; i < validData.length / 2; i++) { int temp = validData[i]; validData[i] = validData[validData.length – i – 1]; validData[validData.length – i – 1] = temp; } The way you are doing it, you swap each … Read more