GTX Nov: Bisecting, Emacs and killing line.

Welcome to this months GTX. How are you? Its cold here in Berlin. Lets get to this months GTX(Git, Terminal, XCode) tips.

Git

1. Finding which commit broke the project first

git-bisect is the command you are looking for if you happen to search for a commit in the past week which silently broke the project and the CI is failing.

I was introduced to this command while at work from my colleague, @ramy_kfoury.

$ git bisect start
$ git bisect bad                 # Current version is bad
$ git bisect good v2.6.13-rc2    # v2.6.13-rc2 is known to be good

Then git will stop at the middle commit. It uses binary search to narrow down possibilities. Then you can test that commit. Testing can be running unit tests at that point, or a set of scripts or manually validating the functionality. Depending on if the error is present or not.

$ git bisect good               # bad if the commit has problem

Eventually we will be left with 1 commit, which is the one that introduced some faults. For more in-depth usage please read this brief reference guide.

2. GitHub style diff on terminal

Ever wanted to see beautiful and clean diff on terminal? We’ve got one.

Diff_So_Fancy is a plugin that does exactly like GitHub UI diff. To install,

$ brew install diff-so-fancy

And to use when required:

$git diff --color | diff-so-fancy

The good part, to make it default, which i recommend, issue this command:

$git config --global core.pager "diff-so-fancy | less --tabs=4 -RFX"

For more customization, take a look at the diff_so_fancy GitHub repo

If for some reason, you prefer side-by-side diff, then there are 2 projects that are worth looking:

cdiff
icdiff

I personally haven’t used icdiff and have limited exposure to cdiff. I will continue with this topic for the next month. Until then have fun bisecting.

Terminal

1. Emacs: Editor of lifetime (for some)

Emacs was started 25 years ago but still remains both the source of inspiration to other text editors and a powerful extensible text editor. I wouldn’t mind to call it more than a text editor to a mini operating system. You can browse web, create web browser and reply email. There’s more. This is how Emacs differs from Vi/Vim. Its great.

I always like to do as much possible without losing context. Terminal is a most for me as I learned and used Git to manage my projects. I don’t use GUI. So I must use terminal every couple of minutes. I wanted terminal to do more. I wanted to use the text editor inside the terminal. I wanted my text editor to be able to quickly edit commit message, Swift source files and write my notes. I will probably go into the details of why I love text based note taking and journal in some future blog post.

Okay lets get Emacs. You can see for yourself.

$ brew update
$ brew install emacs --with-cocoa
$ brew linkapps emacs

You then should be able to run emacs by issuing $ emacs -nw in the terminal. If not, chances are you have a conflicting system emacs. On OSX/ mac OS emacs is installed by default. If your installation doesn’t work then you can hop on this website guide for troubleshooting.

If you want the GUI Emacs then just issue $emacs, the GUI is fairly simple but 2 superior things to terminal mode is that the Fonts/Themes have broader color and size options. Second, you can use the mouse. I don’t know if that’s actually a + point or not.

I cannot however go into the details of setting up Emacs in one post or in tips. I would nonetheless provide an awesome YouTube channel for Emacs starter guide. I highly recommend this guy’s series if you want to see how traditional editor is more than capable of making you productive in the long run.

To get more inspired/see whats possible then this video might be useful for starter.

This video( The editor of lifetime) might be good for your weekend to see the history, design decision and the evolution of Emacs.

Anyway, enough of Emacs. Hopefully, next month I will write my experience with org-mode and other plugins I used daily.

2. Tmux: Spliting Panes

So the idea of sitting in the Terminal continues. I want my terminal to support 2 windows, 1 for zsh and the other for emacs. I use emacs for taking notes, work logs and journal with org-mode. I occasionally need to edit swift code in Emacs but I can if I have to.

To install tmux, please refer to this blog I wrote last month. Anyways, issue this command to quickly install tmux.

$ brew install tmux
$ tmux ;; to run tmux

Splitting the pane with tmux.

CTRL + b then type % creates a pane vertically.
CTRL + b then type " creates a pane horizontally.
CTRL + b then type o (not Zero) switches to another pane
$exit close the current pane

On my setup, I usually put a pane on top for git related work. The lower on runs emacs and I have TODOs and work log on that. Its quite handy.

XCode

1. Delete to the end of line

Like the most people, to delete a entire line, we Select it and then delete selection. i.e CMD + SHIFT + -> , then DEL. Or you use the mouse to make the selection and then delete it. The point is this is 2 step process. Wait, there is a 1 key binding to do it. CONTROL + K. That’s it.

This will delete to the end of the line. The same key binding works for Emacs too.

2. Final Resort

This one might be a old school tips, nonetheless it needs to be put into picture. When everything is fine, and XCode does something beyond your expectation. All you need is to clear artifacts. Every iOS developer knows this:

Clean build, Try
Quit and Restart XCode, Try
Remove derived data, or change the path, Try.
Restart your mac. [This is the least recommended]

As of this writing, I’m using Xcode8 and I had 2 interesting issue:

If somewhere in your code base there is a extension on UIButton, you cant connect @IBAction from xib to UIView subclass.
When compiling large project, the compiler optionally stops at various points and gives compile error. I knew there was no error in it. I just changed some trivial code. However, I just run CMD + R multiple times to bypass each false error.

I hope Xcode 8.2 fixes those issues. Until then, Cheers!