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Is there a way to instantiate objects from a string holding their class name?
...ce() { return new T; }
typedef std::map<std::string, Base*(*)()> map_type;
map_type map;
map["DerivedA"] = &createInstance<DerivedA>;
map["DerivedB"] = &createInstance<DerivedB>;
And then you can do
return map[some_string]();
Getting a new instance. Another idea is ...
Managing constructors with many parameters in Java
...er the following example
public class StudentBuilder
{
private String _name;
private int _age = 14; // this has a default
private String _motto = ""; // most students don't have one
public StudentBuilder() { }
public Student buildStudent()
{
return new Student...
rgdal package installation
...file update
Then, when you get an error such as :
configure: error: proj_api.h not found in standard or given locations.
You can use the following command to find which package you must install to get the missing file :
$ apt-file search proj_api.h
libproj-dev: /usr/include/proj_api.h
...
Can I query MongoDB ObjectId by date?
...cuments created after midnight on May 25th, 1980 */
db.mycollection.find({ _id: { $gt: objectIdWithTimestamp('1980/05/25') } });
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How do I pass parameters into a PHP script through a webpage?
...cript over the web) is using the query string and access them through the $_GET superglobal:
Go to http://yourdomain.com/path/to/script.php?argument1=arg1&argument2=arg2
... and access:
<?php
$argument1 = $_GET['argument1'];
$argument2 = $_GET['argument2'];
?>
If you want the script t...
Using mixins vs components for code reuse in Facebook React
...nding fields.
Source (gist)
define(function () {
'use strict';
var _ = require('underscore');
var ValidationMixin = {
getInitialState: function () {
return {
errors: []
};
},
componentWillMount: function () {
this.assertValidatorsDefined();
},
...
micro:bit 实验07 - 手机调色，点亮一颗 RGB LED · App Inventor 2 中文网
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What is a good regular expression to match a URL? [duplicate]
...t to ensure URL starts with HTTP/HTTPS:
https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
If you do not require HTTP protocol:
[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
To try this out see http...
What are some uses of template template parameters?
...ive an example. Let's pretend that std::vector doesn't have a typedef value_type.
So how would you write a function which can create variables of the right type for the vectors elements? This would work.
template <template<class, class> class V, class T, class A>
void f(V<T, A> ...
Redirecting stdout to “nothing” in python
...eference to the original sys.stdout and set it back after. For example old_stdout = sys.stdout before any of the other code, then sys.stdout = old_stdout when you are done.
– Andrew Clark
Aug 20 '14 at 21:05
...