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Why should the “PIMPL” idiom be used? [duplicate]
...() to be able to use private members of CatImpl. Cat::Purr() would not be allowed such an access without a friend declaration.
Because you then don't mix responsibilities: one class implements, one class forwards.
share...
Creating JS object with Object.create(null)?
...t.create(null) doesn't inherit from anything and thus has no properties at all.
In other words: A javascript object inherits from Object by default, unless you explicitly create it with null as its prototype, like: Object.create(null).
{} would instead be equivalent to Object.create(Object.prototy...
How to access parent Iframe from JavaScript
...
I would recommend using the postMessage API.
In your iframe, call:
window.parent.postMessage({message: 'Hello world'}, 'http://localhost/');
In the page you're including the iframe you can listen for events like this:
window.addEventListener('message', functio...
Efficiently updating database using SQLAlchemy ORM
...ngs in mind when using the ORM and plain SQL in the same transaction. Basically, from one side, ORM data modifications will only hit the database when you flush the changes from your session. From the other side, SQL data manipulation statements don't affect the objects that are in your session.
So...
What is the difference between require_relative and require in Ruby?
... the docs:
require_relative complements the builtin method require by allowing you to load a file that is relative to the file containing the require_relative statement.
For example, if you have unit test classes in the "test" directory, and data for them under the test "test/data" directo...
Explaining Python's '__enter__' and '__exit__'
...
Using these magic methods (__enter__, __exit__) allows you to implement objects which can be used easily with the with statement.
The idea is that it makes it easy to build code which needs some 'cleandown' code executed (think of it as a try-finally block). Some more ex...
CGridCellNumeric - A numeric cell class for the MFC Grid - C/C++ - 清泛网移动版 - 专注IT技能提升
...t of the cell.
Input validation is done on the fly as the user is typing. All validation is done in the EN_UPDATE message handler, so any cut/copy and paste operations are immediately validated. If the user deletes the text in the cell, the value is set to zero.
Using the CGridCellNumeri...
CGridCellNumeric - A numeric cell class for the MFC Grid - C/C++ - 清泛网移动版 - 专注IT技能提升
...t of the cell.
Input validation is done on the fly as the user is typing. All validation is done in the EN_UPDATE message handler, so any cut/copy and paste operations are immediately validated. If the user deletes the text in the cell, the value is set to zero.
Using the CGridCellNumeri...
CGridCellNumeric - A numeric cell class for the MFC Grid - C/C++ - 清泛网移动版 - 专注IT技能提升
...t of the cell.
Input validation is done on the fly as the user is typing. All validation is done in the EN_UPDATE message handler, so any cut/copy and paste operations are immediately validated. If the user deletes the text in the cell, the value is set to zero.
Using the CGridCellNumeri...
CGridCellNumeric - A numeric cell class for the MFC Grid - C/C++ - 清泛网移动版 - 专注IT技能提升
...t of the cell.
Input validation is done on the fly as the user is typing. All validation is done in the EN_UPDATE message handler, so any cut/copy and paste operations are immediately validated. If the user deletes the text in the cell, the value is set to zero.
Using the CGridCellNumeri...