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Legacy Code And Its Improvisation

Legacy Code And Its Improvisation


Legacy Code! Any developer’s fear, distaste, and disappointment. A term that must have gotten your attention at some point in your work life. Well, this expression is not as scary as it may sound. The only thing that makes it scary is the varied meanings it has. Different people and companies use and perceive this term differently. You probably cannot blame them for the same as defining it is pretty tricky.

Some people say it is the code acquired from someone else, others say it is the code written by someone else. Definitions also state that it is the code that is difficult to understand or is written in old, outdated technologies.

Landing onto an appropriate definition for legacy codes is difficult. It is believed that the definition that suits your situation best should be accepted. Speaking of references and expert opinions on the subject, one iconic book that stands out is Michael Feather’s “Working Effectively With Legacy Codes.” According to the book, legacy codes are codes without unit tests.
Let us now dive into our understanding of legacy codes.

Understanding Legacy Codes

Legacy codes can be understood as source codes that are derived or inherited from an earlier version of the program or software from someone else. It is a code which is difficult to understand and is hard to fix. If we go back to the definition by Michael Feather, legacy codes are codes without tests signifying that they are poorly written codes. Without tests, understanding the efficiency of the structure of the code is also difficult.

With the absence of unit tests, there is no way to understand if a code is getting better or worse. The above arguments make it clear that legacy codes are not good codes! Here is where all the problem lies. Everyone has different opinions as to what a good code may look like. A single code may be understood as a good code by one developer and as a poorly written code by the other.

Speaking of the above discussion, there are a few aspects missing. First, codes with tests can also be considered as legacy codes, and second, codes that do not have tests can be easily changed. If you read the tests of the codes and are still clueless as to what the code exactly does, the code is bad. Tested codes may be more difficult to change.

Likewise, if you are maintaining a codebase which is not tested still is easy to understand and change can also be considered as legacy code except for the fact that these codes lack automated tests that do not let them qualify as legacy codes. Keeping in mind all of the above-mentioned cases, we can safely define legacy codes as valuable code which you are afraid to change.

Why maintaining Legacy Codes Is a Challenge?

Before getting onto the different challenges with working and maintaining legacy codes, addressing the most important one out of all of them is important. The biggest and the most important challenge are your assumptions regarding the code. Even if the code is well written, then you may assume it to be bad just because it classifies as legacy code. Apart from your assumptions, other challenges are briefly discussed below.

  • Maintainability 

Although a piece of the software is still maintainable, corporations tend to ignore the fact that their development team is staffed and skilled to maintain an old codebase. This also implies that in order to run obsolete codes and software, new developers coming into the organization also need to learn to work with these technologies. On the other hand, organizations can save a lot of money, energy, and resources if they would altogether stop running old software. Old, outdated codes need extensive maintenance.

  • Security Vulnerability 

From a customer or business perspective, legacy codes may work perfectly fine but they generally face high-security risks. Legacy codes are no longer sponsored by the manufacturer. A single vulnerability can also be a great concern as all programs, databases, or server information can be accessed by attackers.

  • The Problem in Running Old Monolithic Systems

Your entire business application is brought down by an interruption of a non-critical piece of software. This is one of the main challenges businesses face while running monolithic processes. Only because of a tiny part of a system malfunction, nobody wants extra costs or missed sales. Even if different sections are unrelated, changing one part of the structure impacts other sections immediately. In production teams, this leads to major surprises or maybe shocks.

Modern Approaches To Maintain Legacy Codes

Businesses generally turn up to two approaches for maintaining legacy codes. They either erase everything and begin from the scratch with a new approach or they rewrite the existing code after thoroughly studying and examining it. For the same, there are a few modern tools and techniques that can be adopted to mitigate the risks attached to legacy codes.

  • Continuous Delivery 

We would like a safety net that would catch us if we unintentionally deploy a bad construction before beginning to rewrite or deploy a legacy program. This safety net would be able to deploy and return to a previous version quickly and easily. We would have to spend some time creating a deployment process and a release pipeline to be able to do this easily. In the case of continuous delivery, the end objective is to be able to make a release in one phase and a deployment in the other.

  • Detect Unexpected Behaviour Without Error Monitoring

To know how well your legacy service is holding up, you would not trust your gut instinct or count the number of rants from your developers or count the number of support requests that come in. You would not trust the above because they are all dependent on the source which is external to the application to understand if anything is wrong. In case of an error-monitoring system, if the application acts unexpectedly you would be alerted immediately.
When looking for regressions, error tracking is very useful. Bugs can be marked as patched, and we are alerted about the regression if it reappears. Likewise, you can control the progress of upgrading your legacy codebase by using this tool with your favorite problem tracking service.

  • Test Covering 

There is a very strong possibility that the specifications are not very straightforward or well defined when dealing with the legacy code. We want the new module to function in the same way as the framework that exists. The best way to do this is by writing exams. Start writing tests to run against and check its actions against the current code. Then it is possible to reuse the same tests and run them against the new module to ensure that it functions the same way as the current code does.

Benefits of Using Code Review Tools To Manage Legacy Codes

Let’s examine some of the benefits of using code review tools to manage legacy codes.

  • Performance 

Back in the years, there must have been situations when you would have written loops that were not very efficient. This was the case only because you knew that it was not worth optimizing because it would only loop 10 times or so. Now, consider the fact that that bit of processing is now occurring ten thousand times. Sub-optimal circumstances like these become part of the success profile of your application over the long haul, and no one inherently screams about it. But a quick analysis of this code helps you to understand some serious performance improvements.

  • Consistency 

If there are old codebases in your system, it becomes difficult for the new team members to infer expected practices from the same. By familiarity, long-tenured team members know the old layers of the code. But it is like walking around a house where each room has different colors for someone else and trying to find out what color the owner wants the kitchen to be. Periodic analysis of the code can help silence this phenomenon by pure observational influence. But it can also help you find the most confounding and disparate cases and take tactical opportunities to become consistent.

  • Prevention From Defects 

There is a natural tendency for wheels to be reinvented as a codebase sprawls over the years and developers come and go. This is comprehensible. Sooner or later, there is just so much code that you do not have a handle on what it is all about. A formula for unexpected defects is getting poorly duplicated code strewn across the codebase. In one version of the solution, a change in specifications may result in a deliberate fix, with others limping along, secretly being incorrect for months. Periodic reviews of these old codebases would mitigate this and bring forward the understanding of risk spots.


In several ways, the legacy code is synonymous with a vicious loop. The more you would have thought of touching it, the more it languishes and becomes redundant. The more confidence you gain in it the more you can carry it back from the brink and extend your options. When it comes to understanding and maintaining legacy codes, Codegrip can be your go-to option.
Codegrip analyses your code and scans it for any security issues. It finds out code vulnerabilities and shows them separately from other issues also found like code smells and bugs. All code vulnerabilities are noted separately under a tab and also pointed in your code. You can use the suggested solution to find out what changes you can do to remove the security vulnerabilities.


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