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Using emit vs calling a signal as if it's a regular function in Qt
...ou can look at by inspecting the C++ code generated by moc.
For example a foo signal with no parameters generates this member function:
void W::foo()
{
QMetaObject::activate(this, &staticMetaObject, 0, 0);
}
And the code emit foo(); is pre-processed to simply foo();
emit is defined in Q...
WITH CHECK ADD CONSTRAINT followed by CHECK CONSTRAINT vs. ADD CONSTRAINT
...t new data, new constraints. If you disable a constraint with ALTER TABLE foo NOCHECK CONSTRAINT fk_b and then re-enable it with ALTER TABLE foo CHECK CONSTRAINT fk_b it doesn't verify the constraint. ALTER TABLE foo WITH CHECK CHECK CONSTRAINT fk_b is necessary in order to have the data verified....
How do I convert a String object into a Hash object?
..."first second > third"=>"first second > third", "after comma > foo"=>:symbolvalue, "another after comma > foo"=>10}, "bravo"=>{:symbol=>:symbolvalue, :aftercomma=>10, :anotheraftercomma=>"first second > third"}, "charlie"=>{1=>10, 2=>"first second > th...
How can I use “sizeof” in a preprocessor macro?
...macro:
/*
* Simple compile time assertion.
* Example: CT_ASSERT(sizeof foo <= 16, foo_can_not_exceed_16_bytes);
*/
#define CT_ASSERT(exp, message_identifier) \
struct compile_time_assertion { \
char message_identifier : 8 + !(exp); \
}
For example in comment MSVC tells some...
Can PostgreSQL index array columns?
...e to index the individual array elements. For example:
CREATE TABLE test (foo int[]);
INSERT INTO test VALUES ('{1,2,3}');
INSERT INTO test VALUES ('{4,5,6}');
CREATE INDEX test_index on test ((foo[1]));
SET enable_seqscan TO off;
EXPLAIN ANALYZE SELECT * from test WHERE foo[1]=1;
...
Why are empty catch blocks a bad idea? [closed]
...ed. In Python you often see this kind of construction:
try:
result = foo()
except ValueError:
result = None
So it might be OK (depending on your application) to do:
result = bar()
if result == None:
try:
result = foo()
except ValueError:
pass # Python pass is equ...
Please explain some of Paul Graham's points on Lisp
...as str])
;; this is the interesting bit:
(println (str/replace-re #"\d+" "FOO" "a123b4c56"))
This snippet of Clojure code prints out aFOObFOOcFOO. Note that Clojure arguably does not fully satisfy the fourth point on your list, since read-time is not really open to user code; I will discuss what i...
How to get the name of a function in Go?
...ion:
package main
import (
"fmt"
"reflect"
"runtime"
)
func foo() {
}
func GetFunctionName(i interface{}) string {
return runtime.FuncForPC(reflect.ValueOf(i).Pointer()).Name()
}
func main() {
// This will print "name: main.foo"
fmt.Println("name:", GetFunctionName(foo))...
What is Android keystore file, and what is it used for?
This is a general question, but particularly I am interested in it's use for Android. What is a keystore file, and what is it used for?
...
What does ||= (or-equals) mean in Ruby?
.... For example:
a ||= nil # => nil
a ||= 0 # => 0
a ||= 2 # => 0
foo = false # => false
foo ||= true # => true
foo ||= false # => true
Confusingly, it looks similar to other assignment operators (such as +=), but behaves differently.
a += b translates to a = a + b
a ||= b roug...