|Linux| GNU autotool

If you want to porting any library from the distribution to another one,
you should learn GNU autotool firstly.

From porting libqmi, we can learn this fact.

Step 1: install the following libraries.
autotools-dev
libev-dev
autoconfig
automake
autoconf-archive
libtool

Step 2: enter the libraries’ folder
    which included configure.ac, Makefile.am
./configure //in fact, doing autoconf
make
make install


Explanation of files:
configure.ac: input file for Autoconf.
Makefile.am: input file(s) for Automake.

Ref.
https://www.gnu.org/software/automake/faq/autotools-faq.html
https://opensource.com/article/19/7/introduction-gnu-autotools

|OOP| Learn “Factory Pattern” from Android Telephony

Factory pattern is a basic pattern in grant software framework.
We create object, parent, with common interface to create new type of object.
The common interface is a static member-function (static factory method) which creates & returns instances, hiding the details of children.

The following will show a snappiest code of Android Q.