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What is the difference between self-types and trait subclasses?
... extends Tweeter {
| def noCanDo = name
| }
<console>:9: error: illegal inheritance;
self-type Wrong does not conform to Tweeter's selftype Tweeter with User
trait Wrong extends Tweeter {
^
<console>:10: error: not found: value name
...
Const in JavaScript: when to use it and is it necessary?
...ure that contains information that will never change. If there is room for error, var should always be used. However, not all information that never changes in the lifetime of a program needs to be declared with const. If under different circumstances the information should change, use var to indica...
Cannot open backup device. Operating System error 5
Below is the query that I am using to backup (create a .bak ) my database.
21 Answers
...
Delimiters in MySQL
...port it will cause it to be sent to the server, which will report a syntax error. For example, using PHP and MySQLi:
$mysqli = new mysqli('localhost', 'user', 'pass', 'test');
$result = $mysqli->query('DELIMITER $$');
echo $mysqli->error;
Errors with:
You have an error in your SQL syntax; ch...
How to make “if not true condition”?
...
I think it can be simplified into:
grep sysa /etc/passwd || {
echo "ERROR - The user sysa could not be looked up"
exit 2
}
or in a single command line
$ grep sysa /etc/passwd || { echo "ERROR - The user sysa could not be looked up"; exit 2; }
...
Docker can't connect to docker daemon
After I update my Docker version to 0.8.0 , I get an error message while entering sudo docker version :
40 Answers
...
git: patch does not apply
...ord-wise diffs".
Additionally, --whitespace=fix will warn about whitespace errors and try to fix them, rather than refusing to apply an otherwise applicable hunk.
Both options together make the application of a patch more robust against failure, but they require additional attention with respect to ...
Create an enum with string values
...llo" | "world";
var foo: Options;
foo = "hello"; // Okay
foo = "asdf"; // Error!
More : https://www.typescriptlang.org/docs/handbook/advanced-types.html#string-literal-types
Legacy Support
Enums in TypeScript are number based.
You can use a class with static members though:
class E
{
st...
What is an optional value in Swift?
...can be nil
If you try to set a non-optional variable to nil, you'll get an error.
var red: String = "Red"
red = nil // error: nil cannot be assigned to type 'String'
Another way of looking at optionals is as a complement to normal Swift variables. They are a counterpart to a variable which is guara...
sql query to return differences between two tables
...e the same exposed names. Use correlation names to distinguish them. I get error if table names are same and you pull them from two different databases.
– Hammad Khan
Jul 20 '11 at 19:10
...