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What is the difference between Factory and Strategy patterns?
...ent strategies based on the persistence medium. If your data is stored locally in XML it would use one strategy. If the data were remote in a different database, it would use another.
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DROP IF EXISTS VS DROP?
...ent platforms might support it with different syntax, or not support it at all. In PostgreSQL, the syntax is
DROP TABLE IF EXISTS table_name;
The first one will throw an error if the table doesn't exist, or if other database objects depend on it. Most often, the other database objects will be fo...
How do I enable C++11 in gcc?
... program. Create a new file named Makefile (with a capital M). To automatically compile your code just type the make command in a terminal. You may have to install make.
Here's a simple one :
CXX=clang++
CXXFLAGS=-g -std=c++11 -Wall -pedantic
BIN=prog
SRC=$(wildcard *.cpp)
OBJ=$(SRC:%.cpp=%.o)
...
Non-recursive depth first search algorithm
...ting how similar the two are when done non-recursively (as if they're radically different when they're recursive, but still...)
– corsiKa
Mar 11 '11 at 23:49
3
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What does the fpermissive flag do?
...formant code from errors to warnings.
Thus, using -fpermissive will allow some nonconforming code to compile.
Bottom line: don't use it unless you know what you are doing!
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Strangest language feature
What is, in your opinion, the most surprising, weird, strange or really "WTF" language feature you have encountered?
320 An...
NameError: global name 'xrange' is not defined in Python 3
...nchanged, and any
# range(...) replaced with list(range(...))
or replace all uses of xrange(...) with range(...) in the codebase and then use a different shim to make the Python 3 syntax compatible with Python 2:
try:
# Python 2 forward compatibility
range = xrange
except NameError:
p...
How does inline Javascript (in HTML) work?
I know this is bad practice. Don't write code like this if at all possible.
6 Answers
...
Add a new element to an array without specifying the index in Bash
...[@]}]}
h
Here's how to get the last index:
$ end=(${!array[@]}) # put all the indices in an array
$ end=${end[@]: -1} # get the last one
$ echo $end
42
That illustrates how to get the last element of an array. You'll often see this:
$ echo ${array[${#array[@]} - 1]}
g
As you can see, be...
How to rollback just one step using rake db:migrate
...Guide for running migrations.
Here's some more:
rake db:migrate - Run all migrations that haven't been run already
rake db:migrate VERSION=20080906120000 - Run all necessary migrations (up or down) to get to the given version
rake db:migrate RAILS_ENV=test - Run migrations in the given environm...