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What is the curiously recurring template pattern (CRTP)?
... curiously recurring, isn't it? :)
Now, what does this give you? This actually gives the X template the ability to be a base class for its specializations.
For example, you could make a generic singleton class (simplified version) like this
template <class ActualClass>
class Singleton
{
...
os.walk without digging into directories below
...
Does this function actually "walk" through the whole structure and then delete the entries below a certain point? Or is something more clever going on? I'm not even sure how to check this with code. --python beginner
– mathtic...
What encoding/code page is cmd.exe using?
...e and other programs
print gibberish, and sometimes they do not.
First of all, Unicode characters will only display if the
current console font contains the characters. So use
a TrueType font like Lucida Console instead of the default Raster Font.
But if the console font doesn’t contain the char...
How can I create download link in HTML?
... new browser window appear before the download starts. That window will usually be closed when the browser discovers that the resource is a file download.
Note that file types known to the browser (e.g. JPG or GIF images) will usually be opened within the browser.
You can try sending the right hea...
How to avoid 'cannot read property of undefined' errors?
...
Catching all exceptions without re-throwing is bad, and generally using exceptions as part of the expected flow of execution is also not great -- even though in this case it's pretty well contained.
– hugo
...
Why is semicolon allowed in this python snippet?
...ot warrant the use of semicolons to end statements.
So why is this (below) allowed?
15 Answers
...
What can , and be used for?
...iewParam name="id" value="#{bean.id}" />
</f:metadata>
does basically the following:
Get the request parameter value by name id.
Convert and validate it if necessary (you can use required, validator and converter attributes and nest a <f:converter> and <f:validator> in it like...
Bash empty array expansion with `set -u`
...ad. Other patterns, such as ${arr[@]-} or ${arr[@]:0}, are not safe across all major versions of Bash.
As the table below shows, the only expansion that is reliable across all modern-ish Bash versions is ${arr[@]+"${arr[@]}"} (column +"). Of note, several other expansions fail in Bash 4.2, includin...
What is the relative performance difference of if/else versus switch statement in Java?
...ic interface Action {
void execute(String input);
}
And get hold of all implementations in some Map. You can do this either statically or dynamically:
Map<String, Action> actions = new HashMap<String, Action>();
Finally replace the if/else or switch by something like this (leav...
How much is the overhead of smart pointers compared to normal pointers in C++?
..._ptr always has memory overhead for reference counter, though it is very small.
std::unique_ptr has time overhead only during constructor (if it has to copy the provided deleter and/or null-initialize the pointer) and during destructor (to destroy the owned object).
std::shared_ptr has time overhe...