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How can I reverse a NSArray in Objective-C?
...ne. If I see a method that returns an immutable object, I expect it to actually be returning an immutable object. Having it appear to return an immutable object but actual return a mutable object is a dangerous practice to get into.
– Christine
Jul 2 '12 at 22:...
How do I write JSON data to a file?
... codecs.getwriter('utf-8')(f), ensure_ascii=False)
The codecs.getwriter call is redundant in Python 3 but required for Python 2
Readability and size:
The use of ensure_ascii=False gives better readability and smaller size:
>>> json.dumps({'price': '€10'})
'{"price": "\\u20ac10"}'
&...
Iterator invalidation rules
...
C++17 (All references are from the final working draft of CPP17 - n4659)
Insertion
Sequence Containers
vector: The functions insert, emplace_back, emplace, push_back cause reallocation if the new size is greater than the old capa...
Intellij idea cannot resolve anything in maven
...and made sure the following was selected:
Import Maven projects automatically
Create IDEA modules for aggregator projects
Keep source...
Exclude build dir...
Use Maven output...
Generated souces folders: "detect automatically"
Phase to be...: "process-resources"
Automatically download: "sources" &...
How to apply a function to two columns of Pandas dataframe
Suppose I have a df which has columns of 'ID', 'col_1', 'col_2' . And I define a function :
12 Answers
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How to access the correct `this` inside a callback?
...d inside each function and its value only depends on how the function was called, not how/when/where it was defined. It is not affected by lexical scopes like other variables (except for arrow functions, see below). Here are some examples:
function foo() {
console.log(this);
}
// normal functio...
What does character set and collation mean exactly?
...a symbol, the number 0 is the
encoding for 'A', and the combination
of all four letters and their
encodings is a character set.
Now, suppose that we want to compare
two string values, 'A' and 'B'. The
simplest way to do this is to look at
the encodings: 0 for 'A' and 1 for
'B'. Be...
What does the “@” symbol do in Powershell?
...
PowerShell will actually treat any comma-separated list as an array:
"server1","server2"
So the @ is optional in those cases. However, for associative arrays, the @ is required:
@{"Key"="Value";"Key2"="Value2"}
Officially, @ is the "array ...
How to load db:seed data into test database automatically?
...ore every test or just once at the beginning. You could put it in a setup call or in a test_helper.rb file.
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Adding :default => true to boolean in existing Rails column
...
change_column is a method of ActiveRecord::Migration, so you can't call it like that in the console.
If you want to add a default value for this column, create a new migration:
rails g migration add_default_value_to_show_attribute
Then in the migration created:
# That's the more generic way t...