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In which situations do we need to write the __autoreleasing ownership qualifier under ARC?
...declaration means __strong, implicitly:
NSError * e = nil;
Will be transformed to:
NSError * __strong error = nil;
When you call your save method:
- ( BOOL )save: ( NSError * __autoreleasing * );
The compiler will then have to create a temporary variable, set at __autoreleasing. So:
NSErro...
Stop pip from failing on single package when installing with requirements.txt
...
for mac: cat requirements.txt | xargs -n 1 pip install
– Walty Yeung
Sep 4 '16 at 1:32
5
...
Python “raise from” usage
...rinted.
See the raise statement documenation:
The from clause is used for exception chaining: if given, the second expression must be another exception class or instance, which will then be attached to the raised exception as the __cause__ attribute (which is writable). If the raised exception ...
How to get a function name as a string?
...unction.__name__
Using __name__ is the preferred method as it applies uniformly. Unlike func_name, it works on built-in functions as well:
>>> import time
>>> time.time.func_name
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'builtin_fun...
method of iterating over sqlalchemy model's defined columns?
... iterate over the list of columns defined in a SQLAlchemy model. I want it for writing some serialization and copy methods to a couple of models. I can't just iterate over the obj.__dict__ since it contains a lot of SA specific items.
...
Why is Python 3.x's super() magic?
...current implementation instead. He anticipated that using a different name for super() could be a problem:
My patch uses an intermediate solution: it assumes you need __class__
whenever you use a variable named 'super'. Thus, if you (globally)
rename super to supper and use supper but not su...
What's the difference between globals(), locals(), and vars()?
...: '__main__',
}
So far, everything I've said about locals() is also true for vars()... here's the difference: vars() accepts a single object as its argument, and if you give it an object it returns the __dict__ of that object. For a typical object, its __dict__ is where most of its attribute dat...
Should I use a class or dictionary?
...ter want to add some code? Where would your __init__ code go?
Classes are for bundling related data (and usually code).
Dictionaries are for storing key-value relationships, where usually the keys are all of the same type, and all the values are also of one type. Occasionally they can be useful fo...
Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...外，条件表达式中的与或非为分是：and, or, not关键字。
for 循环
从1加到100
1
2
3
4
sum = 0
for i = 1, 100 do
sum = sum + i
end
从1到100的奇数和
1
2
3
4
sum = 0
for ...
Best practices for circular shift (rotate) operations in C++
... are already available in C++.
However, I couldn't find out how I could perform circular shift or rotate operations.
16 Ans...