You don’t need the constant, but I don’t think you can eliminate symbol-to-string: class Example attr_reader :name, :age def initialize args args.each do |k,v| instance_variable_set(“@#{k}”, v) unless v.nil? end end end #=> nil e1 = Example.new :name => ‘foo’, :age => 33 #=> #<Example:0x3f9a1c @name=”foo”, @age=33> e2 = Example.new :name => ‘bar’ #=> #<Example:0x3eb15c @name=”bar”> … Read more
You can indeed do this using the curiously recursive template idiom. It requires nothing from whoever is extending the class that can’t be enforced by the compiler: template<class T> struct Animal { Animal() { reg; //force specialization } virtual std::string name() = 0; static bool reg; static bool init() { T t; AnimalManager::registerAnimal(t.name()); return true; … Read more
Apache Commons has the DurationFormatUtils class for applying a specified format to a time duration. So, something like: long time = System.currentTimeMillis(); //do something that takes some time… long completedIn = System.currentTimeMillis() – time; DurationFormatUtils.formatDuration(completedIn, “HH:mm:ss:SS”);
This will do it a bit more neatly: >>> data = [1,2,3,4,5,6] >>> zip(data[0::2], data[1::2]) [(1, 2), (3, 4), (5, 6)] (but it’s arguably less readable if you’re not familiar with the “stride” feature of ranges). Like your code, it discards the last value where you have an odd number of values.
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.
Addressing the proposed solution from dmckee: While some versions of Bash may allow hyphens in function names, others (MacOS X) do not. I don’t see a need to use return immediately before the end of the function. I don’t see the need for all the semi-colons. I don’t see why you have path-element-by-pattern export a … Read more
Exceptions are not conditionals. The conditional version is clearer. That’s natural: this is straightforward flow control, which is what conditionals are designed for, not exceptions. The exception version is primarily used as an optimization when doing these lookups in a loop: for some algorithms it allows eliminating tests from inner loops. It doesn’t have that … 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
Python 2.6+ next(iter(your_list), None) If your_list can be None: next(iter(your_list or []), None) Python 2.4 def get_first(iterable, default=None): if iterable: for item in iterable: return item return default Example: x = get_first(get_first_list()) if x: … y = get_first(get_second_list()) if y: … Another option is to inline the above function: for x in get_first_list() or []: … Read more
Instead of inducing performance overhead, why not use an extension method to alleviate both problems: public static void Raise(this EventHandler handler, object sender, EventArgs e) { if(handler != null) { handler(sender, e); } } Once defined, you never have to do another null event check again: // Works, even for null events. MyButtonClick.Raise(this, EventArgs.Empty);