大约有 13,071 项符合查询结果（耗时：0.0273秒） [XML]
Abort makefile if variable not set
How could I abort a make/makefile execution based on a makefile's variable not being set/valued?
5 Answers
...
Multiple aggregations of the same column using pandas GroupBy.agg()
Is there a pandas built-in way to apply two different aggregating functions f1, f2 to the same column df["returns"] , without having to call agg() multiple times?
...
What are 'get' and 'set' in Swift?
I'm learning Swift and I'm reading The Swift Programming Language from Apple, I have no Objective C background (only PHP, JS, and other but no Obj C)
...
How is “int* ptr = int()” value initialization not illegal?
...
int() is a constant expression with a value of 0, so it's a valid way of producing a null pointer constant. Ultimately, it's just a slightly different way of saying int *ptr = NULL;
share
...
Does setting Java objects to null do anything anymore?
I was browsing some old books and found a copy of "Practical Java" by Peter Hagger. In the performance section, there is a recommendation to set object references to null when no longer needed.
...
Can you help me understand Moq Callback?
Using Moq and looked at Callback but I have not been able to find a simple example to understand how to use it.
5 Answers...
Unicode character in PHP string
This question looks embarrassingly simple, but I haven't been able to find an answer.
8 Answers
...
Why do I need Transaction in Hibernate for read-only operations?
...
You might actually have reasons to mark transactions as read-only.
Transactions for reading might look indeed strange and often people don't mark methods for transactions in this case. But JDBC will create transaction anyway,...
How to convert string representation of list to a list?
...
>>> import ast
>>> x = u'[ "A","B","C" , " D"]'
>>> x = ast.literal_eval(x)
>>> x
['A', 'B', 'C', ' D']
>>> x = [n.strip() for n in x]
>>> x
['A', 'B', 'C', 'D']
ast.literal_eval:
With ast.literal_eval, you...
Memory management in Qt?
I'm quite new to Qt and am wondering on some basic stuff with memory management and the life of objects. When do I need to delete and/or destroy my objects? Is any of this handled automatically?
...