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How to define “type disjunction” (union types)?
...
First, declare a class with the types you wish to accept as below:
class StringOrInt[T]
object StringOrInt {
implicit object IntWitness extends StringOrInt[Int]
implicit object StringWitness extends StringOrInt[String]
}
Next, declare foo like this:
object Bar {
def foo[T: StringOrInt](x:...
How to get primary key column in Oracle?
...e which is called test and then query
create table test
(
id int,
name varchar2(20),
city varchar2(20),
phone int,
constraint pk_id_name_city primary key (id,name,city)
);
SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner FROM all_constraints cons, all_cons_columns c...
Comparing mongoose _id and strings
...ts.userId.equals(AnotherMongoDocument._id). The ObjectID type also has a toString() method, if you wish to store a stringified version of the ObjectID in JSON format, or a cookie.
If you use ObjectID = require("mongodb").ObjectID (requires the mongodb-native library) you can check if results.userId...
Immutable vs Mutable types
...o
x = 5.0
x += 7.0
print x # 12.0
Doesn't that "mut" x?
Well you agree strings are immutable right? But you can do the same thing.
s = 'foo'
s += 'bar'
print s # foobar
The value of the variable changes, but it changes by changing what the variable refers to. A mutable type can change that wa...
Bash Templating: How to build configuration files from templates with Bash?
...$ENV{$1} ? $ENV{$1} : $&/eg' < template.txt
to replace all ${...} strings with corresponding enviroment variables (do not forget to export them before running this script).
For pure bash this should work (assuming that variables do not contain ${...} strings):
#!/bin/bash
while read -r li...
When to Redis? When to MongoDB? [closed]
...lets you give it a key and look up a single value. Redis itself can store strings, lists, hashes, and a few other things; however, it only looks up by name.
Cache invalidation is one of computer science's hard problems; the other is naming things. That means you'll use Redis when you want to avoi...
Resize HTML5 canvas to fit window
...y: block (it seemed to be defaulting to display: inline which was creating extra space!).
– Elisabeth
Apr 5 '12 at 22:00
15
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How to round to 2 decimals with Python?
...en(str(val))-1), digits)
Basically this adds a really small value to the string to force it to round up properly on the unpredictable instances where it doesn't ordinarily with the round function when you expect it to. A convenient value to add is 1e-X where X is the length of the number string y...
Why is the asterisk before the variable name, rather than after the type?
...plication operator
And indirection is just a single meaning, there is no extra meaning for declaring a pointer, there is just indirection, which is what the dereference operation does, it performs an indirect access, so also within a statement like int *a; this is an indirect access (* means indir...
Script entire database SQL-Server
...d and when.
We wanted to allow our Wix MSI installer to specify connection string and credentials, and needed some way to pass these into the scripts, so once again, using tokens and some conditional logic.
Example script (edited for brevity)
-- Sleep: 5
-- Sleep after creating database to allow...