1. Last lecture…
On refactoring
• We explained what is refactoring, what is
software refactoring
Tutorial 4 • How are they related to other restructuring
More on Refactoring techniques?
• Examples of refactoring
How to refactoring unstructured code?
• Refactoring structured source code into
How to apply refactoring in Eclipse?
goal models
• …
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
1. Refactoring an
Today…
unstructured program
1. How to refactoring unstructured code into • The subject is called “Squirrel Mail”
goal models? • It has 70 KLOC
2. How to use Eclipse to do refactoring? • Developed in PHP
3. Discussions Function call
Foo.php: <?php include(“bar.php”) ?>
4. Relation to your course project • Why it is unstructured?
Foo.php: <a href=“bar.php”/>
<a href=“moo.php”/>
<?php echo “I won super 7!” ?>
Any idea?
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
2. Why a PHP program is
The process
unstructured?
• Every Hyperlink generated from the PHP • Structured program is easier to understand
is an “exit” in the current PHP program /HJDF
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• It may call other PHP routines, other web
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pages, etc. when user click at them ,V VWUXFWXUHG
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• Non-deterministic, how could you tell
([WUDFW
which link will the user click? $67
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3. 5HIDFWRULQJ
• Even “go back” button will change the 5HVWUXFWXUH
behaviour of the program 7HVW WR $QDO]H 4XDOLW *RDO 0RGHO
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• So … 1)5V
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Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
1.1 Refactoring based on
Example
comments
/** Path for SquirrelMail required files. */
define(‘SM_PATH’,’../’);
HQW WKH IROORZLQJ GRHV 6 require_once($SM_PATH . ‘functions/strings.php’);
U 6, 2
10. ∧ S H[LW ∠ S ` ≠ φ
$SM_PATH=set_path ();
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
11. Further … 1.2 Convert into statechart
?php /* login.php */ • Statecharts concisely describe behaviour of a system.
$SM_PATH=set_path ();
$SM_lang=setup_language(); • No comments now, but we need to understand its
$base_uri = findout_base_URI();
$logindisabled = detect_imap_server($base_uri); behaviour, therefore …
if ($logindisabled) {
explain_situation(); $SM_PATH is
exit; undefined
}
do_hook(‘login_cookie’);
$header =onload_function(“redirect.php”); /set_path
display_header($header); $SM_PATH=set_path (); /set_path
load_theme($theme[$theme_default]);
do_hook('login_top');
show_logo();
show_form($loginname, $mailto, $key); $SM_PATH is $SM_PATH
set
do_hook('login_form');
do_hook('login_bottom');
?
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
1.4 Put it together …the high-level statechart of the
1.3 Statechart refactoring unstructured program
Extract Method - Extract States and Transitions based on Hammock graphs
What’s new here? You are refactoring behaviour rather than structures!
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
12. 1.4 Now convert statechart back
1.4 Eliminate GOTO’s
into a program with GOTO’s
• FORTRAN • FPT (Fortran parallelizing transformer, developed at ELIS, Ghent
call EnterURL University, Belgium)
10 call Login • Result of goto elimination:
if (wrongIMAP) goto 30 CALL EnterURL
20 call ShowForm REPEAT
if (wrongKey) goto 20 REPEAT
call EnterForm CALL Login
IF (.not.wrongIMAP) THEN
if (wrongForm) goto 30 REPEAT
call StartWebMail CALL ShowForm
if (loggedOut) goto 10 UNTIL (.not.wrongKey)
if (expired) goto 10 CALL EnterForm
IF(.not.wrongForm)THEN
call Send CALL StartWebmail
Stop ENDIF
30 call ReportError ENDIF
call GoBack UNTIL (.not.loggedOut.or .not.expired.or.wrongIMAP .or.wrongForm)
IF(wrongIMAP.or.wrongForm)
goto 10 THEN
end CALL ReportError
• Rule of thumb: every state is a basic block; adding a label to states with CALL GoBack
ENDIF
multiple incoming transitions; adding GOTO statements for all outgoing UNTIL (.not.wrongIMAP.and.not.wrongForm)
transitions except one; line-up the basic blocks CALL Send
END
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
1.5 Turning structured program into 1.6 Turning it into “pure” goal
an annotated goal model model (AND/OR graph)
•call A …
call B AND
A B
•if (x) then …
call A if(x) OR if(!x)
else
A B
call B
end if
…
[topic]
AND
•call A A
repeat until (s) B
repeat …
call C
OR
until s s C
call B
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
13. 1.7 Introducing softgoals 2. How to refactoring in Eclipse
• Identify NFRs • If you are developing in Java, you are LUCKY!
• Add softgoals to • The Eclipse IDE, JBuilder IDE are very
categorize why comprehensive
there are the • Refactoring was developed in Smalltalk, now
NFRs moved to Java in Eclipse, it has been told in C#
• If possible, one for Visual Studio, etc.
can measure the • It should not be long to see open-source
degree of programming languages to have them
satisfaction for supported, such as PHP
the softgoals • Examples, developed by Jing Su
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
Example 1 – extract method
void f() {
void f() {
...
...
// Compute score
computeScore();
score = a * b + c;
}
score -= discount;
}
void computeScore() {
score = a * b + c;
score -= discount;
}
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
14. Enter a name according to the
comment
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
Example 2 – move method
class Jar { class Jar {
... bool isFragile() {
} switch(material) {
class RoboPacker { case GLASS: return true;
private bool isFragile(Jar foo) { case WOOD: return true;
switch(foo.material) { case TIN: return false;
case GLASS: return true; }}}
case WOOD: return true; class RoboPacker {
case TIN: return false; private bool isFragile(Jar foo) {
} return foo.isFragile();
} }
} }
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
15. Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
Example 3 – lift method
class Jar { class Jar {
bool isFragile() { bool isFragile() {
switch(material) { return material.isFragile();
case GLASS: }}
// complex glass calculation
case WOOD: interface Material { ... }
// complex wood calculation class GlassMaterial:Material { ... }
case TIN: class WoodMaterial:Material { ... }
// complex tin calculation class TinMaterial:Material { ... }
}}}
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
16. 3. Think about these … 4. Relation to your project
1. How to extend refactoring tool support to • Opportunities:
– You may add junit test cases to the code base to
other programming languages such as reveal bugs (publish it to the bug tracking system)
PHP? and fix them (+5%)
– You may apply design patterns, refactoring
2. Can you extend refactoring to techniques on this legacy code base, showing as an
improved complexity metrics (+2.5%)
documents, such as in various formats: – You may tune the performance of the system to
diagrams, textual, xml, etc.? speed up the display, load/save for scalable graphs
(+2.5%)
3. How can know a function is NFR? • Don’t forget your major project task (up to
Can you measure the impact of a NFR 100%!)
– To study the editor methods in the OpenOME and
on a quality attribute? adapt them to the OmniGraphEditor web service.
Spring 2005 ECE450H1S Software Engineering II Spring 2005 ECE450H1S Software Engineering II
