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Rails where condition using NOT NIL
...S NOT NULL
Note that this syntax reports a deprecation (it talks about a string SQL snippet, but I guess the hash condition is changed to string in the parser?), so be sure to add the references to the end:
Foo.includes(:bar).where.not(bars: {id: nil}).references(:bar)
DEPRECATION WARNING: I...
'is' versus try cast with null check
... below the belt. Take a look at this example:
object o = "test";
if (o is string)
{
var x = (string) o;
}
This translates to the following IL:
IL_0000: nop
IL_0001: ldstr "test"
IL_0006: stloc.0 // o
IL_0007: ldloc.0 // o
IL_0008: isinst System.String
IL_000D...
Which is more efficient, a for-each loop, or an iterator?
... = new ArrayList<Integer>();
for (Integer integer : a)
{
integer.toString();
}
// Byte code
ALOAD 1
INVOKEINTERFACE java/util/List.iterator()Ljava/util/Iterator;
ASTORE 3
GOTO L2
L3
ALOAD 3
INVOKEINTERFACE java/util/Iterator.next()Ljava/lang/Object;
CHECKCAST java/lang/Integer
ASTORE...
Using Vim's tabs like buffers
...im -p however be aware that only up to 10 tabs will be display by default. Extra files are loaded into buffers, but not displayed in their own tab.
– IanB
Oct 22 '14 at 23:37
...
How to check 'undefined' value in jQuery
...platform:
if (typeof value === "undefined") {
// ...
}
It returns a string indicating the type of the variable or other unevaluated operand. The main advantage of this method, compared to if (value === undefined) { ... }, is that typeof will never raise an exception in case if variable value ...
“is” operator behaves unexpectedly with integers
...
This can be a very fast check relative to say, checking if two very long strings are equal in value. But since it applies to the uniqueness of the object, we thus have limited use-cases for it. In fact, we mostly want to use it to check for None, which is a singleton (a sole instance existing in o...
Container-fluid vs .container
...s as you change the width of your window/browser by any amount, leaving no extra empty space on the sides ever, unlike how .container does. (Hence the naming: "fluid" as opposed to "digital", "discrete", "chunked", or "quantized").
.container resizes in chunks at several certain widths. In other wo...
What are DDL and DML?
... the transaction making points within groups
SET TRANSACTION – specify characteristics for the transaction
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Relative paths in Python
...
os.path.dirname(__file__) can give an empty string, use os.path.dirname(os.path.abspath(__file__)) instead
– Dmitry Trofimov
Mar 10 '15 at 22:03
15
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Threading in a PyQt application: Use Qt threads or Python threads?
... (although the caveat above still applies.)
Non-blocking I/O
Threads add extraordinarily complexity to your application. Especially when dealing with the already complex interaction between the Python interpreter and compiled module code. While many find event-based programming difficult to follow...