Square Root Amend and Fixup

[RAlekri]

Use the checklist to tick off the sub-tasks as you complete them. Some of the tasks rely on material that has already
been covered in the lesson so try and use what you have learnt. The commands are provided if required though.

• Create and switch to the square-root-amend-fixup branch.
• Rebase the branch onto main to ensure it is up-to-date (Hint - you may not have all changes that have been
  merged into main).
• Copy and paste the example to the docstring of the square_root() function that shows the consequence of trying to
  divide by zero.
• Commit your changes with an appropriate error message.
• Correct the spelling error
• Amend the previous commit

You have now used git commit --amend, lets try git commit --fixup.

• Make an empty commit.
• Add another example to the square_root() function's example section.
• Commit the change as a fixup to the commit which added the first example.
• Perform an interactive rebase to automatically squash the changes.
• Remove the empty commit and push your changes.
• Make a pull request and once approved merge.
• Delete your local square-root-amend-fixup branch

Checkout the square-root-amend-fixup branch

This branch doesn't exist so needs creating.

git switch -c square-root-amend-fixup

Rebase the branch onto main

We need to ensure we have an up-to-date version of main before we can rebase onto it.

git switch main
git pull
git switch -
git rebase main

Add a warning about square roots of negative numbers

Currently the arithmetic.square_root() function has a problem, it returns the square root of negative numbers.

from pythonmaths import arithmetic
arithmetic.square_root(-2)
-1.4142135623730951

Obviously this is wrong as square roots of negative numbers should be complex.

We can improve the function by changing it to the following.

if x < 0:
    print("WARNING : you have supplied a negative number, the square roof is complex.")
return x ** (1 / 2)

Commit your changes

git add -u
git commit -m "Adds warning to square_root() if number is negative"

Correct the spelling error

Did you spot it? The example above had roof instead of root. Correct this in the docstring so it reads as shown
below.

print("WARNING : you have supplied a negative number, the square roof is complex.")

Amend the previous commit

Rather than making a new commit amend the previous commit with the change.

git add -u
git commit --amend

Make an empty commit

git commit --allow-empty -m "Empty commit to try out fixup"

Add another example to the square_root() function's example section

    >>> arithmetic.square_root(-2)
        WARNING : you have supplied a negative number, the square roof is complex.
        (8.659560562354934e-17+1.4142135623730951j)

Commit the change as a fixup

You need to know the hash of the commit made above that you amended (use git log --oneline) or you can use the
relative reference HEAD~1

git add -u
git commit --fixup HEAD~1

Perform an interactive rebase to automatically squash the changes

You will either need the hash of the commit before the one you are fixing up (use git logp to find this) or
you can use HEAD~3 (the fixup itself is currently a commit and so you have to go back an extra commit relative to
HEAD).

git rebase -i --autosquash HEAD~3

A text editor should open and the commit with the message staring fixup! should have fixup and not pick next to
it. If that isn't the case change it to fixup. Save the file and exit the text editor (this should be nano in which
case use Ctrl + o followed by Ctrl + x).

Remove the empty commit and push your changes

We can remove the empty commit and push our changes.

git reset HEAD~1
git push

Make a pull request and once approved merge

Go to GitHub and make a pull request to merge you changes in, assigning it to you have teamed up with for this
exercise. Once approved merge the pull request to main.

Delete your local square-root-amend-fixup branch

We can now switch to main, pull down the merged changes and delete the local copy of the square-root-amend-fixup

git switch main
git pull
git branch -d square-root-amend-fixup