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What does the exclamation mark mean in a Haskell declaration?
...to look inside it, probably through a pattern match:
case f of
Foo 0 _ _ _ -> "first arg is zero"
_ -> "first arge is something else"
This is going to execute enough code to do what it needs, and no more. So it will create a Foo with four parameters (because you can't lo...
Unique constraint on multiple columns
...ied from technet's documentation, is in the form of:
CONSTRAINT constraint_name UNIQUE [ CLUSTERED | NONCLUSTERED ]
(
column [ ASC | DESC ] [ ,...n ]
)
Therefore, the resuting table definition would be:
CREATE TABLE [dbo].[user](
[userID] [int] IDENTITY(1,1) NOT NULL,
[fcode] [int] ...
ERROR:'keytool' is not recognized as an internal or external command, operable program or batch file
... C:\Program Files\Java\jdk1.6.0_21\bin>keytool -list -alias androiddebugkey -keystore .android\debug.keystore -storepass android -keypass android. the error i got is keytool error: java.lang.Exception: Key...
Read only the first line of a file?
...od (Python 2 docs, Python 3 docs):
with open('myfile.txt') as f:
first_line = f.readline()
Some notes:
As noted in the docs, unless it is the only line in the file, the string returned from f.readline() will contain a trailing newline. You may wish to use f.readline().strip() instead to rem...
How to change the session timeout in PHP?
...u are using PHP's default session handling with cookies, setting session.gc_maxlifetime along with session_set_cookie_params should work for you like this:
// server should keep session data for AT LEAST 1 hour
ini_set('session.gc_maxlifetime', 3600);
// each client should remember their session id...
Is there Selected Tab Changed Event in the standard WPF Tab Control
...
I tied this in the handler to make it work:
void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (e.Source is TabControl)
{
//do work when tab is changed
}
}
sh...
Python: reload component Y imported with 'from X import Y'?
... This doesn't seem to work always. I have a module Foo which has an __init__.py that fetches a submodule... I'll post an answer as a counterexample.
– Jason S
Oct 17 '17 at 22:32
...
Get button click inside UITableViewCell
...kOnCellAtIndex:withData:)]) {
[self.delegate didClickOnCellAtIndex:_cellIndex withData:@"any other cell data/property"];
}
}
In table view controller cellForRowAtIndexPath after dequeing the cell, set the above properties.
cell.delegate = self;
cell.cellIndex = indexPath.row; // Set i...
How to perform Callbacks in Objective-C
...newer) option is to use blocks:
@interface MyClass: NSObject
{
void (^_completionHandler)(int someParameter);
}
- (void) doSomethingWithCompletionHandler:(void(^)(int))handler;
@end
@implementation MyClass
- (void) doSomethingWithCompletionHandler:(void(^)(int))handler
{
// NOTE: copyin...
What are some uses of decltype(auto)?
...p;&
auto x6a = { 1, 2 }; // decltype(x6a) is std::initializer_list<int>
decltype(auto) x6d = { 1, 2 }; // error, { 1, 2 } is not an expression
auto *x7a = &i; // decltype(x7a) is int*
decltype(auto)*x7d = &i; // error, declared type is not plain declt...