Be Careful when sourcing a script

The story comes from my assistant for my colleague to debug an issue.

Process A Logic as below:

while Process A does not get result Y from script ddcc.sh
      sh ddcc.sh
			    

and the script logic for ddcc.sh as below:

. /lib/ipp88x.sh
local h=$(ipp88x_name)
result=Y
			    

The phenomenon is, Process A invoke ddcc.sh again and again, and
never stop.

There is no file /lib/ipp88x.sh exist!
and when run the script ddcc.sh, the code below:

. /lib/ipp88x.sh
			    

will stop the script ddcc.sh and return error immediately!
with error below:

ddcc.sh: .: line 3: can't open '/lib/ipp88x.sh'
			    

and the code below will never reached

result=Y
			    

. MyScript
			    

The execute command (a single period) followed by the name of the
script.

The difference between that and using the sh command is that
the sh command starts a new process and the execute command does
not.