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Django admin: how to sort by one of the custom list_display fields that has no database field
How could I sort Customers, depending on number_of_orders they have?
3 Answers
3
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C++ catching all exceptions
...
try{
// ...
} catch (...) {
// ...
}
will catch all C++ exceptions, but it should be considered bad design. You can use c++11's new current_exception mechanism, but if you don't have the ability to use c++11 (legacy code systems requiring a rewrite), then you have no name...
Why can lambdas be better optimized by the compiler than plain functions?
...assing them to a function template will instantiate a new function specifically for that object. The compiler can thus trivially inline the lambda call.
For functions, on the other hand, the old caveat applies: a function pointer gets passed to the function template, and compilers traditionally hav...
How to run a python script from IDLE interactive shell?
...s.call(['python', 'helloworld.py']) # Just run the program
subprocess.check_output(['python', 'helloworld.py']) # Also gets you the stdout
With arguments:
subprocess.call(['python', 'helloworld.py', 'arg'])
Read the docs for details :-)
Tested with this basic helloworld.py:
import sys
if le...
Difference between passing array and array pointer into function in C
... eax, 0Fh
add eax, 0Fh
shr eax, 4
shl eax, 4
mov [ebp+var_C], eax
mov eax, [ebp+var_C]
call sub_401730
call sub_4013D0
mov [ebp+var_8], 2
mov [ebp+var_4], 4
lea eax, [ebp+var_8]
mov [esp+18h+var_18], eax
call sub_401290
call _getch
leave
retn
So th...
What is the colon operator in Ruby?
..." # false
:foo.equal? :foo # true
This makes comparing two symbols really fast (since only a pointer comparison is involved, as opposed to comparing all the characters like you would in a string), plus you won't have a zillion copies of the same symbol floating about.
Also, unlike strings, sy...
Copy data into another table
...the column list for newTable is optional if you are specifying a value for all columns and selecting columns in the same order as newTable's schema):
INSERT INTO newTable (col1, col2, col3)
SELECT column1, column2, column3
FROM oldTable
...
How to display the default iOS 6 share action sheet with available share options?
...he UIActivityViewController stated in the other answer makes this trivial. All you have to do is specify the text/image/URL that you want to share and present the activity view controller modally and iOS will automatically display all applicable sharing services. Examples:
Objective-C
- (void)shar...
When is std::weak_ptr useful?
...want to keep them in memory, so you hold a strong pointer to them. Periodically, you scan the cache and decide which objects have not been accessed recently. You don't need to keep those in memory, so you get rid of the strong pointer.
But what if that object is in use and some other code holds a s...
Access-control-allow-origin with multiple domains
...onfig I would like to specify more than one domain for the access-control-allow-origin directive. I don't want to use * . I've tried this syntax:
...