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subtle differences between JavaScript and Lua [closed]
...xample, if foo ~= 20 then ... end.
Lua 5.3 and up use ~ for binary bitwise XOR, whereas JS uses ^.
In Lua, any type of value (except nil and NaN) can be used to index a table. In JavaScript, all non-string types (except Symbol) are converted to strings before being used to index an object. For exam...
__FILE__, __LINE__, and __FUNCTION__ usage in C++
... It's possible with constexpr that uses a lookup table or bitwise XOR, etc. to obfuscate any string literals in your binary. There are various examples out there if you search. Of course obfuscation is just obfuscation and not security, but if you don't want to make your files and functions...
How can I convert immutable.Map to mutable.Map in Scala?
...ke.scala:223)
// at scala.collection.immutable.Map$Map2.default(Map.scala:110)
// at scala.collection.MapLike$class.apply(MapLike.scala:134)
// at scala.collection.immutable.Map$Map2.apply(Map.scala:110)
// at $anon$1.default(<console>:9)
// at $anon$1.default(<console>:8)
// at sc...
What is the best algorithm for overriding GetHashCode?
... quite how important that is.)
This is better than the common practice of XORing hashcodes for two main reasons. Suppose we have a type with two int fields:
XorHash(x, x) == XorHash(y, y) == 0 for all x, y
XorHash(x, y) == XorHash(y, x) for all x, y
By the way, the earlier algorithm is the one c...
What is getattr() exactly and how do I use it?
...alues:
>>> dir(1000)
['__abs__', '__add__', ..., '__trunc__', '__xor__', 'bit_length', 'conjugate', 'denominator', 'from_bytes', 'imag', 'numerator', 'real', 'to_bytes']
>>> obj = 1000
>>> for attr_name in dir(obj):
... attr_value = getattr(obj, attr_name)
... pr...
How do you set, clear, and toggle a single bit?
... string with the bitwise NOT operator (~), then AND it.
Toggling a bit
The XOR operator (^) can be used to toggle a bit.
number ^= 1UL << n;
That will toggle the nth bit of number.
Checking a bit
You didn't ask for this, but I might as well add it.
To check a bit, shift the number n to the ri...
`testl` eax against eax?
...rom the same bag of tricks that holds the idea of clearing a register with XOR EAX,EAX (which i saw on someone's license plate in Colorado!) rather than the obvious but maybe slower MOV EAX, #0 (i use an older notation).
In asm, like perl, TMTOWTDI.
...
How to implement one-to-one, one-to-many and many-to-many relationships while designing tables?
...D UNIQUE (SGID)
);
INSERT INTO gov(GID, Name, Address, TermBegin)
values(110, 'Bob', '123 Any St', '1-Jan-2009');
INSERT INTO STATE values(111, 'Virginia', 2000000, 110);
One-to-many (1:M)
A relationship is one-to-many if and only if one record from table A is
related to one or more records in...
async await return Task
...
Read these:
TPL: http://msdn.microsoft.com/en-us/library/dd460717(v=vs.110).aspx and Tasks: http://msdn.microsoft.com/en-us/library/system.threading.tasks(v=vs.110).aspx
Async: http://msdn.microsoft.com/en-us/library/hh156513.aspx
Await: http://msdn.microsoft.com/en-us/library/hh156528.aspx
...
Get statistics for each group (such as count, mean, etc) using pandas GroupBy?
...
A B -0.810 -1.32 4 -0.372500 4
C D -0.110 -1.65 3 -0.476667 3
E F 0.475 -0.47 2 0.455000 2
G H -0.630 -0.63 1 1.480000 1
The result above is a little annoying to deal with because of the nested column labels, and also beca...