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How to create a protocol with methods that are optional?
...ier for a method after compilation. You can provide the correct identifier by using the @selector() directive and specifying the name of the method.
If the data source in this example implements the method, the title is used; otherwise, the title remains nil.
...
How to establish a connection pool in JDBC?
...vailable 3rd party components:
Apache DBCP - This one is
used internally by Tomcat, and by
yours truly.
c3p0
Apache DBCP comes with different example on how to setup a pooling javax.sql.DataSource. Here is one sample that can help you get started.
...
Shell - Write variable contents to a file
...able:
starts with -e
starts with -n
starts with -E
contains a \ followed by an n
should not have an extra newline appended after it
and so they cannot be relied upon for arbitrary string contents.
In bash, you can use "here strings" as:
cat <<< "$var" > "$destdir"
As noted in t...
Why not infer template parameter from constructor?
...
@KyleStrand Yes, by saying 'class template arguments cannot be deduced from their constructors because [example that does not use any constructor]', this answer is completely irrelevant. I genuinely can't believe it was accepted, reached +29,...
An efficient way to transpose a file in Bash
...$ ./shell.sh
0 3 6 9
1 4 7 10
2 5 8 11
Performance against Perl solution by Jonathan on a 10000 lines file
$ head -5 file
1 0 1 2
2 3 4 5
3 6 7 8
4 9 10 11
1 0 1 2
$ wc -l < file
10000
$ time perl test.pl file >/dev/null
real 0m0.480s
user 0m0.442s
sys 0m0.026s
$ time awk -f ...
Where is nodejs log file?
...
There is no log file. Each node.js "app" is a separate entity. By default it will log errors to STDERR and output to STDOUT. You can change that when you run it from your shell to log to a file instead.
node my_app.js > my_app_log.log 2> my_app_err.log
Alternatively (recommended...
What do linkers do?
...n a program is compiled, the compiler converts the source file into object byte code. This byte code (sometimes called object code) is mnemonic instructions that only your computer architecture understands. Traditionally, these files have an .OBJ extension.
After the object file is created, the li...
How to create a generic array in Java?
...t the array and the values in the array are of the correct type.
It works by using class literals as runtime type tokens, as discussed in the Java Tutorials. Class literals are treated by the compiler as instances of java.lang.Class. To use one, simply follow the name of a class with .class. So, St...
How to empty/destroy a session in rails?
...er.
reset_session
Here's the documentation on this method: http://api.rubyonrails.org/classes/ActionController/Base.html#M000668
Resets the session by clearing out all
the objects stored within and
initializing a new session object.
Good luck!
...
Create a “with” block on several context managers? [duplicate]
...or instance A lock, a db connection and an ip socket.
You can acquire them by:
5 Answers
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