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#+TITLE: Don't wait! Write your own (ya)snippets.
#+AUTHOR: Tony Aldon
LICENSE: CC BY-SA 4.0

* Init
Hey everybody, welcome to the emacsconf 2019, I'm TONY and I hope this
video will help you to get started with the yasnippet package.

* Table of content
At first we'll have a look at some useful commands and variables
provide by yasnippet: yas-expand, yas-describe-tables, and
yas-snippet-dirs. 

Then we'll write a snippet for the js-mode using the command
yas-new-snippet which pops a new buffer for writing a snippet.

Ready, OK, let's go!!

* (1) yas-expand
In javascript, to consol.log some text we just type LOG and hit TAB to
expand the snippet.  It moves the cursor between the parentheses.

We can do the same with a if statment, and we move through the snippet
with the 'tab' key.

* (2) yas-describe-tables
To display the available snippets of the buffer's mode, we use the
command yas-describe-tables.  We scroll down.  And we see that
'function' is a snippet and 'f' is the key. If we type 'f' and hit
'tab' it expands the snippet.

* (3) snippet's description
Let's go back to the describe table, we scroll down.  And with the
cursor on the snippet named 'function', we hit 'return'.  Now in
another window we can inspect the snippet definition.

The first line would tell emacs this is a snippet.  The second and
third lines define the name and the key of the snippet.  And after
this line, the snippet's body starts.

The dollar sign indicates where the cursor is going to be, and The
numbers signify which order 'tab' is going to move you through the
snippet. 

The cursor will move first, before the open parenthese to let you fill
the function's name.  Then, will move, after the open parenthese, to
let you fill the function's arguments.  And finally the cursor will
end at 0.

Now, we go back to the javascript file.

* (4) yas-snippets-dirs
To know where our snippets are defined, let's see the variable
yas-snippet-dirs which lists the top-level snippet directories. 

We can see that some of my snippets are defined in this directory.
Let's have a look on it.

Well, for instance, the available snippets for the latex mode are
defined in this directory 'latex dash mode' directory, and each file
defines exactly one snippet. 

* (5) express snippet
Now assume that you're using the framework 'express' to build APIs,
and, you want that APP to be the key of the snippet that looks like
this.  For that, let's just call the command yas-new-snippet.

It pops a new buffer for writing the snippet.  We enter the name:
express app The key, which is: app.  And for the organization in the
describe table, we add this snippet to the group: express. 

For testing, we enter: blabla.  And we save it. And this will
automatically load the snippet.

Let's go back to the javascript file.  We hit 'tab', and it expands
it.  Now we copy the text we want for the snippet.  And we add the end
position of the cursor.

We save it and go back to the javascript file.  Now we hit 'tab' and
it expands it as this way.  Ok, pretty cool.

Now in the cycle of the cursor, we add two positions.  First position
and second position.  This allows us to write on the fly the 'method'
and the 'path' off the 'app' object.

Let's back to the javascript file, we expand the snippet, and now we
can write the method and the path. 

Ok, to be more readable, we add placeholders for the first two
positions of the cursor.  We add 'method' and we add 'path'.  Let's
have a look on it.

We go back to the javascript file.  Now we expand it, we see the
placeholders.  We replace it, the method and the path.

Yeah!!!  We did it.  We've written the snippet 'express app', and it
works.

For the end, we check in the describe table if the snippet appears.
We go back to the describe table, we scroll down, and there it is.

Ok, now you can write your own snippets.

* Thanks!
I hope you've enjoyed the video.  I'm tony, Thank you for watching,
keep learning and stay alive.