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Setting variable to NULL after free
...he call to free, it's not only not best practice, it's wrong. For example: foo* bar=getFoo(); /*more_code*/ free(bar); /*more_code*/ return bar != NULL;. Here, setting bar to NULL after the call to free will cause the function to think it never had a bar and return the wrong value!
...
Why is lazy evaluation useful?
...ges let you reason about function definitions using equational reasoning.
foo x = x + 3
Unfortunately in a non-lazy setting, more statements fail to return than in a lazy setting, so this is less useful in languages like ML. But in a lazy language you can safely reason about equality.
Secondly, ...
Setting CSS pseudo-class rules from JavaScript
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Just place the css in a template string.
const cssTemplateString = `.foo:[psuedoSelector]{prop: value}`;
Then create a style element and place the string in the style tag and attach it to the document.
const styleTag = document.createElement("style");
styleTag.innerHTML = cssTemplateString;...
Object.watch() for all browsers?
... syntax from the Firefox way of adding observers. Instead of :
var obj = {foo:'bar'};
obj.watch('foo', fooChanged);
You do:
var obj = {foo:'bar'};
var watcher = createWatcher(obj);
watcher.watch('foo', fooChanged);
Not as sweet, but as an observer you are notified immediately.
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How to replace a string in multiple files in linux command line
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cd /path/to/your/folder
sed -i 's/foo/bar/g' *
Occurrences of "foo" will be replaced with "bar".
On BSD systems like macOS, you need to provide a backup extension like -i '.bak' or else "risk corruption or partial content" per the manpage.
cd /path/to/you...
Iterate over a list of files with spaces
...ld replace the word-based iteration with a line-based one:
find . -iname "foo*" | while read f
do
# ... loop body
done
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Using python map and other functional tools
... through the different functions, but to access it directly from maptest:
foos = [1.0,2.0,3.0,4.0,5.0]
bars = [1,2,3]
def maptest(foo):
print foo, bars
map(maptest, foos)
With your original maptest function you could also use a lambda function in map:
map((lambda foo: maptest(foo, bars)), ...
node.js shell command execution
...f the data has been read off of stdout. As such, when you run
console.log(foo.stdout);
you get whatever happens to be stored in foo.stdout at the moment, and there's no guarantee what that will be because your child process might still be running.
Second is that stdout is a readable stream, so 1...
How to pretty print XML from the command line?
...bxml2-utils
This utility comes with libxml2-utils:
echo '<root><foo a="b">lorem</foo><bar value="ipsum" /></root>' |
xmllint --format -
Perl's XML::Twig
This command comes with XML::Twig perl module, sometimes xml-twig-tools package:
echo '<root><foo ...
Learning Python from Ruby; Differences and Similarities
...of attribute: one that is executable.
So for example:
>>> class foo:
... x = 5
... def y(): pass
...
>>> f = foo()
>>> type(f.x)
<type 'int'>
>>> type(f.y)
<type 'instancemethod'>
That difference has a lot of implications, like for example...