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BLE协议—广播和扫描 - 创客硬件开发 - 清泛IT社区，为创新赋能！
...广播方式的报文有4种，分别为可连接的非定向广播（ADV_IND）、可连接的定向广播（ADV_DIRECT_IND）、可扫描非定向广播（ADV_SCAN_IND）、不可连接的非定向广播（ADV_NONCONN_IND）
4种广播的使用场景各不相同
可连接的非定向广播（ADV...
Python: most idiomatic way to convert None to empty string?
...ot ''. s(0) should return '0', not ''. Likewise for an object that defines __bool__ or __nonzero__.
– Oddthinking
May 13 '17 at 3:27
...
Get notified when UITableView has finished asking for data?
...interface declaration for UITableView, you will find NSMutableArray member _reloadItems right under _insertItems and _deleteItems. (I've had to rework code I inherited because of this change.)
– Walt Sellers
Feb 21 '13 at 6:32
...
Determine the type of an object?
...
On instances of object you also have the:
__class__
attribute. Here is a sample taken from Python 3.3 console
>>> str = "str"
>>> str.__class__
<class 'str'>
>>> i = 2
>>> i.__class__
<class 'int'>
>>> class...
Zip lists in Python
...x. list, string, tuple, dictionary)
Output (list)
1st tuple = (element_1 of numbers, element_1 of letters)
2nd tuple = (e_2 numbers, e_2 letters)
…
n-th tuple = (e_n numbers, e_n letters)
List of n tuples: n is the length of the shortest argument (input)
len(numbers) =...
How to find the operating system version using JavaScript?
...dows 3.11' => 'Win16',
'Windows 95' => '(Windows 95)|(Win95)|(Windows_95)',
'Windows 98' => '(Windows 98)|(Win98)',
'Windows 2000' => '(Windows NT 5.0)|(Windows 2000)',
'Windows XP' => '(Windows NT 5.1)|(Windows XP)',
'Windows Server 2003' => '(Windows NT 5.2)',
'Windows Vista' =&g...
Test if lists share any items in python
...
def lists_overlap3(a, b):
return bool(set(a) & set(b))
Note: the above assumes that you want a boolean as the answer. If all you need is an expression to use in an if statement, just use if set(a) & set(b):
...
How does type Dynamic work and how to use it?
...rized:
class DynImpl extends Dynamic {
import reflect.runtime.universe._
def applyDynamic[A : TypeTag](name: String)(args: A*): A = name match {
case "sum" if typeOf[A] =:= typeOf[Int] =>
args.asInstanceOf[Seq[Int]].sum.asInstanceOf[A]
case "concat" if typeOf[A] =:= typeOf[St...
What is the maximum recursion depth in Python, and how to increase it?
...mple context manager like this:
import sys
class recursionlimit:
def __init__(self, limit):
self.limit = limit
self.old_limit = sys.getrecursionlimit()
def __enter__(self):
sys.setrecursionlimit(self.limit)
def __exit__(self, type, value, tb):
sys.setr...
django admin - add custom form fields that are not part of the model
....models import YourModel
class YourModelForm(forms.ModelForm):
extra_field = forms.CharField()
def save(self, commit=True):
extra_field = self.cleaned_data.get('extra_field', None)
# ...do something with extra_field here...
return super(YourModelForm, self).save(c...