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How do you build a Singleton in Dart?
...leton:
class Singleton {
static final Singleton _singleton = Singleton._internal();
factory Singleton() {
return _singleton;
}
Singleton._internal();
}
You can construct it like this
main() {
var s1 = Singleton();
var s2 = Singleton();
print(identical(s1, s2)); // true
pri...
Insert Update trigger how to determine if insert or update
... I like to write SELECT 1 FROM INSERTED too as I think it signalizes intent more clearly, but I would be disapointed by MSSQL programmers if this makes any difference in this context...
– Lukáš Lánský
Apr 30 '14 at 11:12
...
When should we call System.exit in Java
...you're not changing the exit code (which defaults to 0) - basically it's pointless.
When the docs say the method never returns normally, it means the subsequent line of code is effectively unreachable, even though the compiler doesn't know that:
System.exit(0);
System.out.println("This line will n...
count vs length vs size in a collection
...en "size" usually refers to number of actual elements.
I think the main point is down to human language and idioms, the size of a string doesn't seem very obvious, whilst the length of a set is equally confusing even though they might be used to refer to the same thing (number of elements) in a col...
SQL Add foreign key to existing column
...SQL command in SQL Server 2008 to update a table with a foreign key constraint:
6 Answers
...
What is the MySQL VARCHAR max size?
...
Keep in mind that MySQL has a maximum row size limit
The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, not counting BLOB and TEXT types. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are...
Best way to work with transactions in MS SQL Server Management Studio
... AdventureWorks;
GO
BEGIN TRANSACTION;
BEGIN TRY
-- Generate a constraint violation error.
DELETE FROM Production.Product
WHERE ProductID = 980;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() AS ErrorNumber
,ERROR_SEVERITY() AS ErrorSeverity
,ERROR_STATE() AS Err...
Formatting “yesterday's” date in python
... If you happen to be working with pandas, you can as well use: print((pd.to_datetime('Today') - pd.Timedelta('1 days')).strftime('%m%d%y'))
– etna
Oct 2 '17 at 7:39
...
Are the decimal places in a CSS width respected?
...t Iam seeing inconsistency in chrome,safari and firefox.
For e.g if 33.3% converts to 420.945px
chrome and firexfox show it as 421px.
while
safari shows its as 420px.
This seems like chrome and firefox follow the floor and ceil logic while safari doesn't.
This page seems to discuss the same prob...
JComboBox Selection Change Listener?
...tionEvent e) {
doSomething();
}
});
@John Calsbeek rightly points out that addItemListener() will work, too. You may get 2 ItemEvents, though, one for the deselection of the previously selected item, and another for the selection of the new item. Just don't use both event types!
...