Policies/Kdepim Coding Style: Difference between revisions

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== Purpose of this document ==
 
This document describes the recommended coding style for kdepim. Nobody is
forced to use this style, but to have consistent formatting of the source code
files it is strongly recommended to make use of it.
 
''In short: Kdepim coding style follows the''
[http://techbase.kde.org/Policies/Kdelibs_Coding_Style Kdelibs coding style].
 
== The rules for Kdepim ==
 
*don't use any <TAB>s
*Trim the lines
*Only single empty lines should be used
*The first line, the last line(s) may not be empty
*no "one line" if-statement
 
== Migration ==
 
As discussed at the KDEPIM meeting, Berlin, 3 March 2013, all the files of KDEPIM will
be reviewed to follow the coding style.  This will be done over a long time,
directory after directory, for each of the
rules defined above.  For each rule, one can find one or two script(s). 
 
== Check the objects ==
 
As a first approach, not any object may have binary change after applying one of the rules.
To check this, one uses the '''Check-the-Objects.sh'''. Download the script: [[Media:Check-the-Objects.sh.gz]]
 
The script can be used with one of the commands:
* save
* test
* clean
 
'''An example:'''
 
{{Input|1=cd <some_kdepim_directory>
mkdir build
cd build
ccmake ../
make}}
{{Output|1=<span style="color:Fuchsia">Scanning dependencies of target gpgmepp</span>
[  0%] <span style="color:green">Building CXX object gpgme++/CMakeFiles/gpgmepp.dir/gpgmepp_automoc.cpp.o</span>
[  0%] <span style="color:green">Building CXX object gpgme++/CMakeFiles/gpgmepp.dir/exception.cpp.o</span>
[  0%] <span style="color:green">Building CXX object gpgme++/CMakeFiles/gpgmepp.dir/context.cpp.o</span>
...}}
 
{{Input|1=Check-the-Objects.sh save}}
The script makes a copy of all the objects and a "time stamp":
{{Output|1=save the object ./kholidays/tests/CMakeFiles/testzodiac.dir/testzodiac.cpp.o
save the object ./kholidays/tests/CMakeFiles/testzodiac.dir/testzodiac_automoc.cpp.o
...
all objects are saved}}
 
Now, one makes somes change(s) on the source(s) and:
 
{{Input| 1=make}}
 
Depending on the Makefile, some objects will be compiled again:
 
{{Output| 1=<span style="color:Fuchsia">Scanning dependencies of target akonadi-kde</span>
[ 17%] <span style="color:green">Building CXX object akonadi/CMakeFiles/akonadi-kde.dir/entitytreeview.cpp.o</span>
[ 17%] <span style="color:green">Building CXX object akonadi/CMakeFiles/akonadi-kde.dir/itemfetchjob.cpp.o</span>
[ 17%] <span style="color:green">Building CXX object akonadi/CMakeFiles/akonadi-kde.dir/statisticsproxymodel.cpp.o</span>
...
<span style="color:Fuchsia">Scanning dependencies of target akonadi-kmime</span>
[ 56%] <span style="color:green">Building CXX object akonadi/kmime/CMakeFiles/akonadi-kmime.dir/standardmailactionmanager.cpp.o</span>}}
 
{{Input|1=Check-the-Objects.sh test}}
 
The script finds all the new objects, makes a comparision with the saved version:
{{Output|1=test the object ./akonadi/CMakeFiles/akonadi-kde.dir/statisticsproxymodel.cpp.o
test the object ./akonadi/CMakeFiles/akonadi-kde.dir/entitytreeview.cpp.o
test the object ./akonadi/CMakeFiles/akonadi-kde.dir/itemfetchjob.cpp.o
test the object ./akonadi/kmime/CMakeFiles/akonadi-kmime.dir/standardmailactionmanager.cpp.o
all tests are OK
}}
 
== Check the assembler files ==
If we add or remove some lines, the debug informations included in the object file will be change also.
 
This is the case with the test/change of "''Only single empty lines should be used''", "''First line, last line(s) may not be empty''" and some more test/change below (''adding some blocks'' with { and }).
 
For this reason it is no more possible to compare the objects.
We have to compare the assembler files.
This works pretty well for the version with '''CMAKE_BUILD_TYPE''' set to ''release''.
For the version with '''CMAKE_BUILD_TYPE''' set to ''debug'', we must remove all the debug informations before the comparision could take place.
 
=== Generate the assembler files ===
 
To generate the assembler files, we only need to modify the ''build.make'' in every folder.
 
The script '''Prepare-build_make_files.sh''' works on the all directory, finds the line with the compiler command,
duplicates the line, add a ''-S option'' and changes the name of the output to ''somename.s''.
After a new ''make'' command, we can save all the assembler files with the script '''Check-the-assembler_code.sh'''.
Download the script: [[Media:Prepare-build_make_files.sh.gz]]
 
=== Remove the debug informations ===
 
The biggest part of the debug informations beginns with the directive line
*.Ldebug_info0
We drop all the next lines.
 
We drop also the lines with the directive .loc
They contain an information about the source line (here 123) we need later to drop the lines
* movl $123, %edx
* movl $123, %ecx
 
The lines with
* .string "/home/guy-kde/projects/kdepimlibs/akonadi/agentbase.cpp:454"
will be also removed.
 
The script to check the assembler files can be used in the same way as the one above (Check-the-Objects.sh).
To check this, one uses the '''Check-the-assembler_code.sh'''. Download the script: [[Media:Check-the-assembler_code.sh.gz]]
 
The script can be used with one of the commands:
* save
* test
* clean
 
== The scripts ==
The first script is '''to check''' a single file or a complete directory for all .h and
.cpp files.
 
If present, the second script '''makes the changes''' for a single file or a complete
directory for all .h and .cpp files.  For some complicated situations, the
script makes no change.
 
One can use the scripts for own work.It is recommanded to use them in this order.
 
==== don't use any <TAB>s ====
*coding-style-check-Tabs.sh
*coding-style-change-Tabs.sh
 
Download the scripts: [[Media:Tabs.tar.gz]]
 
The output of the '''check''' script is:
{{Output|1=check the file /home/guy-kde/projects/kdepimlibs/ktnef/ktnefparser.cpp
1->308: Tab at 16:  stream_ >> i;              // i <- attribute type & name
2->311: Tab at 16:  stream_ >> i;              // i <- data length
3->326: Tab at 22:  case attATTACHMENT:        // try to get attachment info
4->367: Tab at 16:  stream_ >> u;      // u <- checksum
a  b    c            d}}
 
This shows:
* the name of the file which is under test.
* the number of occurence('''a'''), the line number('''b'''), the position found('''c''') and the line itself('''d''').
 
The '''change''' script:
*makes a substitution of any <TAB> with eight spaces,
*The change works for the complete source, even within comments and strings,
*That might be too much and changes the vertical alignment of the code.
 
==== Trim the lines ====
 
*coding-style-check-Trim.sh
*coding-style-change-Trim.sh
 
Download the scripts: [[Media:Trim.tar.gz]]
 
The output of the '''check''' script is:
{{Output|1=check the file /home/guy-kde/Software/coding-style-check/trim.cpp
1->51: Space(s) at end of line (28):  QVariant m_matchData;}}
 
This shows:
* the name of the file which is under test.
* the number of occurence, the line number, the position found and the line itself.
 
 
The '''change''' script:
*remove all trailing space(s).
 
==== Only single empty lines should be used ====
 
*coding-style-check-Twice.sh
*coding-style-change-Twice.sh
 
The output of the '''check''' script is:
{{Output|1=check the file /home/guy-kde/projects/kdepimlibs/syndication/rss2/enclosure.cpp
1->25: next empty line found
2->26: next empty line found
3->30: next empty line found}}
   
This shows:
* the name of the file which is under test.
* the number of occurrences and the line numbers.
 
The '''change''' script:
*removes all the next empty line(s).
 
Refer to http://techbase.kde.org/Policies/Kdelibs_Coding_Style#Whitespace
 
==== First line, last line(s) may not be empty ====
 
Some of the sources have a first empty lines, some have one or more empty last line(s).
*coding-style-check-First-Last.sh
*coding-style-change-First-Last.sh
 
The output of the '''check''' script is:
{{Output|1=check the file /home/guy-kde/Software/coding-style-check/trim.cpp
The first line is empty
The last line is empty}}
   
The '''change''' script:
*removes the first line if empty, all the last empty line(s).
 
==== Use one space after each keyword ====
 
Refer to http://techbase.kde.org/Policies/Kdelibs_Coding_Style#Whitespace
 
====no "one line" if-statement====
 
The following code:
{{Output|1=if ( a > b ) c = 123;}}
is correct, but we prefer the block:
{{Output|1=if ( a > b ) {
  c = 123;
} }}
which is easier to read, to modify.
 
It is also possible to put a breakpoint at the line in the block.
 
Refer to http://techbase.kde.org/Policies/Kdelibs_Coding_Style#Braces
 
As the awk-script is too simple to recognize all the if-statements, we get some false alarm and
we can't make the changes automatically.
 
*coding-style-check-One-Line-If.sh
 
The output of the '''check''' script is:
{{Output|1=check the file /home/guy-kde/Software/coding-style-check/if-example.cpp
1->25: one-line-if found}}

Latest revision as of 18:19, 10 March 2016

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