DARING CHANGES IN ENTERPRISE GUIDE WITH A SAFETY NET

Transcription

1 DARING CHANGES IN ENTERPRISE GUIDE WITH A SAFETY NET Lorne Salter, salchootchkin@gmail.com ABSTRACT Version Control is a super undo button and more according to Dave Thomas(1), a vault with every version that anyone who worked on the project has saved with a safe copy and version number assigned to every state of the project and every folder structure change with some systems. This is a rapid live demo of the basics of working with SAS under version control and a popular version control system. Note that this is version control from the programmer's point of view, not from a managers "change management perspective, though both benefit from a well introduced system. Installation: A volunteer from the room will download and install the software, hopefully in under 10 minutes on a second computer and projector while the demonstration continues. A typical day with EG and version control: how version control can support a programmer doing something daring, such as adding a generic macro to extract test data, use it in tests, then clean itself up to an existing critical project. Even though one is not sure how it will turn out, version control gives the confidence that one can backtrack or put a promising idea on a well structured side track. Two tricks to commit files and add messages to both the version control log and a header change log will be demonstrated. Reverting (super undoing) will be shown. Documentation and initial configuration: after you have seen how version control works, I will demonstrate initial setup of the version control repository. INTRODUCTION last year Gordon Cumming and I presented version control with CVS and Subversion, and how to set up automatic file references to development, test and production (see WUSS 2008.) This is a follow-up to that paper, a quick live demo of the basics of working with SAS and a popular version control system. I am performing here with backup but no real safety net, so please be prepared for anything. Version Control is like a super undo button (1) or a time machine that allows you to go back hours, days, months or longer to, for example, before the boss told you to make a load of baffling changes, then took another job. It is a a vault with every version that anyone who worked on the project has saved with a safe copy and version number assigned to every state of the project, even every folder structure change with some systems. If you are smart, it also has very helpful messages accompanying each change. As a matter of fact, academic researchers exposed flaws in certain voting machines by examining version repositories which the company had conveniently or inadvertently left on line. They contained comments like, this security feature will never work. This is a demonstration, so let's get on with it! Installation is fast and easy I hope. Can or a volunteer please come up here and downloading and installing Tortoise Subversion for Windows as I speak. Documentation for this particular package is very well written, and there's a wealth of well presented navigable troubleshooting help on line for most specific issues. Here is the manual. Later, we are going to follow this quick start to set up a repository. TYPICAL DAY WITH ENTERPRISE GUIDE AND VERSION CONTROL I am doing something daring today, writing a generic macro to extract test data, use the data in tests, then clean itself up. But it is not quite working yet. I do not know if a long set of if conditions will work as a macro parameter. Before I add the ifcondit parm, I save, of course, but once I am into the testing I will need to save again and will not have the old version unless I clutter up my directory with _v If, heaven forbid, I am hit by a truck, the poor soul who inherits the project will have to figure out which of the versions are tested and stable, which are experimental and which is the latest and greatest.

2 After I save, I go into Windows Explorer and observe, that because the the file is under version control, the icon has changed form green to red because the file is no longer in sync with the one saved in the vault. I right click on the file, and notice special version control menu items. Note here that the documentation has much better screen shots than I can provide. One option is COMMIT and doing so gives me a dialog box. Notice the message box into which you can enter a message about your change. Once you click OK, you get a verbose log that tells you several things including the new version number. The version control I am using here is Subversion, and the Windows user interface is called Tortoise. It is the easiest to demonstrate with because it is very visual, using icons, special symbols within Windows(tm) Explorer(tm), and especially color. It is also free as in beer and free as in free of restrictive copyright (Gnu Public License). As SAS people, we also appreciate having a command version, and many version control theorists advocate using the command line version of Subversion. Then I select commit and observe the messages Now begin the daring change.

3 The file icon now returns to green, meaning it is in sync with the vault. Now I add my risky new condition parameter and test it. It seems OK but could use more testing. I decide to save and commit again before further testing, but instead of exiting Enterprise Guide(tm), here is a trick: after I save, I go to the save as dialog inside Enterprise Guide(tm), I right click on the project in the save as dialog menu. (Yes, the screen shot in this document is just a word processor, but it works the same.)

4 See the SVN menu options. SVN commit is the option I want and it gives me the dialog box. Again, the message box is key here it attaches a message to the version and is added to a log I will show you how to access in a minute. saving risky long condition parameter. Warning, a basic commit should work fine from the Enterprise Guide(tm) save as menu, but the many fancy options such as revert should be done from windows explorer or the command line as they may not appear or work correctly in the dialog. Also, SAS Enterprise Guide does not like it one bit and may punish you, if you replace a file it is working on from the OS or other application, so be respectful of the finicky power of both Enterprise Guide the versioning software. Doing things like reverting are pretty rarely done. But when you need them you need them bad. You are encouraged by best practices to commit (and of course test) each small increment. So suppose I revise my new feature. I am working on another trick, using command line subversion and X to shell if you are so lucky to have it enabled. With X to shell we may be able to build a change log and simultaneously use the powerful command line version of Subversion to enter messages to Subversion. You would carefully highlight this and use the run selected code. (If it works, this is definitely a trick you need to perform with focus), and the results of the commit would flash past in the windows command prompt window. The header change log might look something like this: /* Change log: X 'svn commit -m Changed location of long condition macro parm to after basic sample '; X 'svn commit -m Added long condition macro parm '; */

5 Now I volume test an even longer condition and it performs very slowly. I decide to take another approach. Instead of removing the parm and everything related to it from the macro parm list AND in the actual macro code, I exit EG, open win explorer, right click on the Test_data.sas program and select revert to, and select the earlier version. Now, my working copy is back the way it was. If you have already committed the new version, you can still restore ANY earlier version by selecting which one you want to restore to your working copy and committing it. It does not really eliminate the last changed version, it just makes the latest version the same as an earlier one. One more example, I am coding away merrily and want to replace this whole section. It is nearly lunch and I am hungry. So I quickly write a new section and delete the old one below it and save it. I get back from lunch and I scroll down and see that the highlight inadvertently was extended to the end of the program. The rest of my program is gone and I feel like I have fallen off the trapeze. If I saved and committed before I started on the new section, then no problem. I exit Enterprise Guide, right click on the program and select revert. I just was saved by the version control safety net. BENEFITS A version control project library folder contents should look more like this Program_a_extracts_data Program_b_transforms_data

6 Program_c_compares_data Program_d_exports_data Program_d_exports_data_one_time_for_directors Not like this: Program_a_extracts_data Program_a_corrected Program_a_v_2 Program_1_with_new_codes Program_b_transforms_data Program_b_transforms_data _b1 Program_b_transforms_data2_debugged Program_c_compares_data Program_c_compares_data_w_new_paycodes Program_d_exports_data Program_d_exports_data_one_time_for_directors Have you ever had a folder like that? Ever inherited one like that. I have. Which program is the right one? Why were changes made? Can I talk to the original programmer? He's in Tasmania for an indefinite visit? Another benefit. You can view all the changes and change messages from the Tasmanian traveler if he used version control.

7 Version control is not just for computer code. Any file can be put in the repository, and it is often, and some say should be more often, used for everything, documentation, flow charts,screen shots and so forth. Unreadable binary files like Enterprise Guide(tm) projects will not be able to benefit from the built in or freestanding diff tools the way code does, but that did not stop us versioning our 140 Platform LSF flows at a major bank data mart I worked on for 3 years. It was essential to our small team. CONCLUSION Version control is a great safety net that can catch you when the inevitable falls come, if you approach programming with panache as an artistic, indeed acrobatic activity. Even if you think of yourself only as a business analyst, if someone likes a report you do, you may be called on to expand or modify it. Adding robust version control to Enterprise Guide(tm) makes a great platform to improve and develop your productivity and skills. REFERENCES 1. Hunt, Andrew and Thomas, Dave The pragmatic Programmer: form Journeyman to Master. NY, White Plains, Addison Wesley.

8 CONTACT INFORMATION: Lorne Salter 2127 W. Nicolet Ave. Phoenix AZ SAS and all other SAS Institute Inc. product or service names are registered trademarks or trademarks of SAS Institute Inc. in the USA and other countries. indicates USA registration. Other brand and product names are registered trademarks or trademarks of their respective companies.