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How to limit the maximum value of a numeric field in a Django model?
...
Here is the best solution if you want some extra flexibility and don't want to change your model field. Just add this custom validator:
#Imports
from django.core.exceptions import ValidationError
class validate_range_or_null(object):
compare = lambda self,...
How to remove from a map while iterating it?
...r this pattern which is slightly clearer and simpler, at the expense of an extra variable:
for (auto it = m.cbegin(), next_it = it; it != m.cend(); it = next_it)
{
++next_it;
if (must_delete)
{
m.erase(it);
}
}
Advantages of this approach:
the for loop incrementor makes sense as an ...
int a[] = {1,2,}; Weird comma allowed. Any particular reason?
...at the end.
e.g.
for_each(my_inits.begin(), my_inits.end(),
[](const std::string& value) { std::cout << value << ",\n"; });
There isn't really any advantage for the programmer.
P.S. Though it is easier to autogenerate the code this way, I actually always took care not to put the ...
When to use reinterpret_cast?
... Nice example! I would replace short for uint16_t and unsigned char for uint8_t to make it less obscure for human.
– Jan Turoň
Aug 27 '18 at 9:41
1
...
C# using streams
...read from stream, for example StreamReader can be used to read from Stream string not byte[]. if you will give FileStream as a parameter it will read from File, if NetworkStream from socket.
– Arsen Mkrtchyan
Sep 10 '09 at 17:55
...
Catch a thread's exception in the caller thread in Python
...rns to the main thread immediately when an exception is called
requires no extra user defined classes because it does not need:
an explicit Queue
to add an except else around your work thread
Source:
#!/usr/bin/env python3
import concurrent.futures
import time
def func_that_raises(do_raise)...
Maven Install on Mac OS X
...
Download Maven from its homepage
Follow the installation instructions:
Extract the distribution archive, i.e.apache-maven-3.3.9-bin.tar.gz to the directory you wish to install Maven 3.3.9. The subdirectory apache-maven-3.3.9 will be created from the archive.
Optional: Add the MAVEN_OPTS environm...
How to pass arguments to a Button command in Tkinter?
...ss', command=fce)
See: http://infohost.nmt.edu/tcc/help/pubs/tkinter/web/extra-args.html
For more buttons you can create a function which returns a function:
def fce(myX, myY):
def wrapper(x=myX, y=myY):
pass
pass
pass
return x+y
return wrapper
button1 = ...
MySQL select where column is not empty
...
Compare value of phone2 with empty string:
select phone, phone2
from jewishyellow.users
where phone like '813%' and phone2<>''
Note that NULL value is interpreted as false.
...
Why are const parameters not allowed in C#?
...od type system, a type system where when you say "this variable contains a string" that the variable actually contains a reference to a string (or null). We absolutely do not want to put a C-style "const" modifier into the type system because we don't want the type system to be a lie. We want the ty...