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What is an invariant?
...e. A function or method that ensures that the invariant holds is said to maintain the invariant.
For instance, a binary search tree might have the invariant that for every node, the key of the node's left child is less than the node's own key. A correctly written insertion function for this tree wi...
Sql Server 'Saving changes is not permitted' error ► Prevent saving changes that require table re-cr
...save it, if I try to edit the table design, like change a column type from int to real, I get this error:
16 Answers
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Python string class like StringBuilder in C#?
...
It is not a premature optimization to avoid fragile, interpreter-dependant optimizations. If you ever want to port to PyPy or risk hitting one of the many subtle failure cases for the optimization, do things the right way.
– Veedrac
Nov 3 ...
How to make a great R reproducible example
...r for grouped tbl_df (class grouped_df) from dplyr. In these cases you can convert back to a regular data frame before sharing, dput(as.data.frame(my_data)).
Worst case scenario, you can give a text representation that can be read in using the text parameter of read.table :
zz <- "Sepal.Length ...
Why are flag enums usually defined with hexadecimal values
...ively low-level topics where the memory layout of data matters. Using it hints at the fact that that's the situation we're in now.
Also, i'm not sure about C#, but I know that in C x << y is a valid compile-time constant.
Using bit shifts seems the most clear:
[Flags]
public enum MyEnum
{
...
Copy entire contents of a directory to another using php
... path
* @param string $dest Destination path
* @param int $permissions New folder creation permissions
* @return bool Returns true on success, false on failure
*/
function xcopy($source, $dest, $permissions = 0755)
{
$sourceHash = hashDirectory($source);
...
Is there a label/goto in Python?
...d do with a goto using first class functions. For example:
void somefunc(int a)
{
if (a == 1)
goto label1;
if (a == 2)
goto label2;
label1:
...
label2:
...
}
Could be done in python like this:
def func1():
...
def func2():
...
funcmap =...
How to load an ImageView by URL in Android? [closed]
...droid_icon_256.png");
public void onClick(View v) {
startActivity(new Intent(this, IndexActivity.class));
finish();
}
private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
public DownloadImageTask(ImageView bmImage) {
this.bmIm...
What are some common uses for Python decorators? [closed]
... def wrapper(*arg):
t = time.clock()
res = func(*arg)
print func.func_name, time.clock()-t
return res
return wrapper
@time_dec
def myFunction(n):
...
share
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impro...
Android RatingBar change star colors [closed]
...
Step #2: Create your own LayerDrawable XML resources for the RatingBar, pointing to appropriate images to use for the bar. The original styles will point you to the existing resources that you can compare with. Then, adjust your style to use your own LayerDrawable resources, rather than built-in on...