Hi,

Firstly, thanks for this great Vim plugin.

Look at the documentation to see the details.

Tested on VIM 8.1

In order to add proof that the code work as it should, I choose to usehttps://github.com/junegunn/vader.vim as test runner.

Why we need this ?

Extract Variable is part of the must-have tools of a programmer as this refactoring is done too many times.

If Extract Method is the most important of refactorings, Extract Variable is its ready assistant. It turns out that in order to extract methods, you often must extract variables first.

@TestpublicvoidallOnes()throwsException {for (inti=0;i<20;i++)g.roll(1);assertEquals(20,g.score());}

And we ended up with this:

privatevoidrollMany(intn,intpins) {for (inti =0;i <n;i++) {g.roll(pins);    }}@TestpublicvoidallOnes()throwsException {rollMany(20,1);assertEquals(20,g.score());}

The sequence of refactorings was as follows:

1. Extract Variable: The 1 in g.roll(1) was extracted into a variable named pins.
2. Extract Variable: The 20 in assertEquals(20, g.score()); was extracted into a variable named n. The two variables were moved above the for loop.
3. Extract Method: The for loop was extracted into the rollMany function. The names of the variables became the names of the arguments.
4. Inline: The two variables were inlined. They had served their purpose and were no longer needed.

Another common usage for Extract Variable is to create an explanatory variable.

if (employee.age >60 &&employee.salary >150000)ScheduleForEarlyRetirement(employee);

This might read better with an explanatory variable:

booleanisEligibleForEarlyRetirement =employee.age >60 &&employee.salary >150000;if (isEligibleForEarlyRetirement)ScheduleForEarlyRetirement(employee);

From "Clean Craftsmanship: Disciplines, Standards, and Ethics (Robert C. Martin Series) (English Edition)" written by Robert C. Martin