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Pipe output and capture exit status in Bash
... Bonus: in the end the exit status is actually an exit status and not some string in a file.
Situation:
someprog | filter
you want the exit status from someprog and the output from filter.
Here is my solution:
((((someprog; echo $? >&3) | filter >&4) 3>&1) | (read xs; exit...
How do I get the number of elements in a list?
...e number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or
a collection (such as a dictionary, set, or frozen set).
len is implemented with __len__, from the data model docs:
object.__len__(self)
Called to implement the built-in funct...
How do you find out the type of an object (in Swift)?
...
If you have a String that is passed as type Any then type(of:) will output Any, not String.
– ScottyBlades
Jun 17 '18 at 21:56
...
Use email address as primary key?
...
String comparison is slower than int comparison. However, this does not matter if you simply retrieve a user from the database using the e-mail address. It does matter if you have complex queries with multiple joins.
If you ...
Passing references to pointers in C++
...
Your function expects a reference to an actual string pointer in the calling scope, not an anonymous string pointer. Thus:
string s;
string* _s = &s;
myfunc(_s);
should compile just fine.
However, this is only useful if you intend to modify the pointer you pass to...
Flask-SQLalchemy update a row's information
...:
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80), unique=True)
data = db.Column(db.PickleType())
def __init__(self, name, data):
self.name = name
self.data = data
def __repr__(self):
return '<User %r>' % self.username
...
Java regex email
...\.[A-Z]{2,6}$", Pattern.CASE_INSENSITIVE);
public static boolean validate(String emailStr) {
Matcher matcher = VALID_EMAIL_ADDRESS_REGEX.matcher(emailStr);
return matcher.find();
}
Works fairly reliably.
s...
Error to install Nokogiri on OSX 10.9 Maverick?
...gdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -Wwrite-strings -Wno-missing-field-initializers -Wshorten-64-to-32 -Wno-long-long -fno-common -pipe -g -DXP_UNIX -O3 -Wall -Wcast-qual -Wwrite-strings -Wconversion -Wmissing-noreturn -Winline -DNOKOGIRI_USE_PACKAGED_LIBRARIES -DNOK...
Why should eval be avoided in Bash, and what should I use instead?
...not been rewritten as safe-for-use-in-situation-XYZ; in our case, it's any string that has not been formatted so as to be safe for evaluation.
Sanitizing data appears easy at first glance. Assuming we're throwing around a list of options, bash already provides a great way to sanitize individual el...
Why are joins bad when considering scalability?
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@slolife regular sql views are like running an extra query in the background on the fly when you use a query that references the view. But you can also tell sql server to "materialize" some views. When you do this, sql server will keep an extra copy of the view's data, j...