大约有 40,000 项符合查询结果（耗时：0.0288秒） [XML]
Django: Get list of model fields?
...s which (ultimately) inherits from models.Model . I want to get a list of all the fields defined for this model. For example, phone_number = CharField(max_length=20) . Basically, I want to retrieve anything that inherits from the Field class.
...
What is the advantage of GCC's __builtin_expect in if else statements?
...
I guess it should be something like:
cmp $x, 0
jne _foo
_bar:
call bar
...
jmp after_if
_foo:
call foo
...
after_if:
You can see that the instructions are arranged in such an order that the bar case precedes the foo case (as opposed to the C code). This can utilise the CPU ...
Is False == 0 and True == 1 an implementation detail or is it guaranteed by the language?
.....] Boolean values behave like the values 0 and 1, respectively, in almost all contexts, the exception being that when converted to a string, the strings "False" or "True" are returned, respectively.
There is also, for Python 2:
In numeric contexts (for example when used as the argument to an ...
BaseException.message deprecated in Python 2.6
...of the exception hierarchy.
Provides an 'args' attribute that contains all arguments passed
to the constructor. Suggested practice, though, is that only a
single string argument be passed to the constructor."""
__str__ and __repr__ are already implemented in a meaningful way,
especiall...
Getting the SQL from a Django QuerySet [duplicate]
...t the queryset's query attribute.
>>> queryset = MyModel.objects.all()
>>> print(queryset.query)
SELECT "myapp_mymodel"."id", ... FROM "myapp_mymodel"
share
|
improve this answer...
How to get number of entries in a Lua table?
...ual, any of 3, 5 and 9 are valid results for #t. According to the manual, calling # on non-sequences is undefined. That means that any result (-1, 3, 3.14, 5, 9) is valid.
– cubuspl42
May 12 '14 at 20:08
...
Immutability of Strings in Java
...t, and changing a reference. s2 still points to the same object as we initially set s1 to point to. Setting s1 to "Help!" only changes the reference, while the String object it originally referred to remains unchanged.
If strings were mutable, we could do something like this:
String s1 = "Hello";
St...
What are good uses for Python3's “Function Annotations”
...
I think this is actually great.
Coming from an academic background, I can tell you that annotations have proved themselves invaluable for enabling smart static analyzers for languages like Java. For instance, you could define semantics like sta...
Threading pool similar to the multiprocessing Pool?
...
I just found out that there actually is a thread-based Pool interface in the multiprocessing module, however it is hidden somewhat and not properly documented.
It can be imported via
from multiprocessing.pool import ThreadPool
It is implemented using a...
Shards and replicas in Elasticsearch
...e need to create an index.
When you create an index (an index is automatically created when you index the first document as well) you can define how many shards it will be composed of. If you don't specify a number it will have the default number of shards: 5 primaries. What does it mean?
It mean...