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What is the syntax rule for having trailing commas in tuple definitions?
...
In all cases except the empty tuple the comma is the important thing. Parentheses are only required when required for other syntactic reasons: to distinguish a tuple from a set of function arguments, operator precedence, or to a...
Django TemplateDoesNotExist?
... assuming that you have the apps configured in settings.py like this:
INSTALLED_APPS = (
'appname1',
'appname2',
'appname3',
)
By default Django will load the templates under templates/ directory under every installed apps. So with your directory structure, we want to move our templat...
What is the definition of “interface” in object oriented programming
... one of the more overloaded and confusing terms in development.
It is actually a concept of abstraction and encapsulation. For a given "box", it declares the "inputs" and "outputs" of that box. In the world of software, that usually means the operations that can be invoked on the box (along with ar...
Unix's 'ls' sort by name
...t the FILEs (the current directory by default). Sort entries alpha‐betically if none of -cftuvSUX nor --sort is specified.:
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What is Lazy Loading?
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It's called lazy loading because, like a lazy person, you are putting off doing something you don't want to. The opposite is Eager Loading, where you load something right away, long before you need it.
If you are curious why peop...
SqlAlchemy - Filtering by Relationship Attribute
...ts = Patient.query.filter(Patient.mother.has(phenoscore=10))
or join (usually faster):
patients = Patient.query.join(Patient.mother, aliased=True)\
.filter_by(phenoscore=10)
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Why does calling a function in the Node.js REPL with )( work?
Why is it possible to call function in JavaScript like this, tested with node.js:
3 Answers
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How to delete or add column in SQLITE?
...upports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a column, remove a column, or add or remove constraints from a table.
You can:
create new table as the one you ar...
Catching multiple exception types in one catch block
...fining the exceptions). Even given that there are exceptions you want to "fall through", you should still be able to define a hierarchy to match your needs.
abstract class MyExceptions extends Exception {}
abstract class LetterError extends MyExceptions {}
class AError extends LetterError {}
cla...
How can jQuery deferred be used?
... // or may not have been retrieved using an
// XHR request.
});
Basically, if the value has already been requested once before it's returned immediately from the cache. Otherwise, an AJAX request fetches the data and adds it to the cache. The $.when/.then doesn't care about any of this; all ...