Linters

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Having attended several meetups and conferences, I have heard of the term “linter” used. I wasn’t sure what it was and was surprised that I had not used it before. But actually, I have but didn’t know that it was a linter.“A linter or lint refers to tools that analyze source code to flag programming errors, bugs, stylistic errors, and suspicious constructs” (A) In CS50, an Introduction to Computer Science, we used a program called “style50”, that would look for stylistic errors. Wow I was already using a linter and didn’t even know it.

How it works is when you pass code to a linter it will scan the code and give messages. The return messages could be syntax errors, structural problems like the use of undefined variables, or best practice or code style guideline violations. Whats great about is is that we can get immediate feedback on bugs that might only show their head in a specific instance, and that isn’t something we would want to release into production!

“The term “lint” was derived from the name of the undesirable bits of fiber and fluff found in sheep’s wool.”(B) Stephen Johnson created the first lint program out of need to check his own code. In my mind, I kind of compare it to the tests that we create today. The linter is a large generic test framework rather than the small tests that we write for specific apps today, but the concept is the same. Here is a quote from Stephen:  

I originally wrote lint to help me debug the YACC grammar I was writing for C. I had the grammar written, but no way to test it! I could run it on the body of C code that existed, but I had no way of telling whether I had correctly “understood” the programs. So I hit on the idea of checking the consistency between function calls and definitions – Stephen Johnson (C)

Thanks to Stephen’s need, linters are now used all over the software engineering space. If you use Javascript here are some links for JS linters

 

 

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