Snippets for Gedit: how to change the text in a placeholder to make the letters uppercase?

I’m trying to improve a snippet for Gedit that helps me write shell scripts.

Currently, the snippet encloses the name of a variable into double quotes surrounding curly brackets preceded with a dollar sign. But to make the letters uppercase, I have to switch to the caps-lock mode or hold down a shift key when entering the words. Here is the code of the snippet:

"\${$1}"

I would like that the snippet makes the letters uppercase for me. To do that, I need to know how to make text uppercase and change the content of a placeholder.

I have carefully read the following articles:

https://wiki.gnome.org/Apps/Gedit/Plugins/Snippets

https://blogs.gnome.org/jessevdk/2009/12/06/about-snippets/

https://www.marxists.org/admin/volunteers/gedit-sed.htm

How do you create a date snippet in gedit?

But I still have no idea how to achieve what I want — to make the letters uppercase. I tried to use the output of shell programs, a Python script, the regular expressions — the initial text in the placeholder is not changed. The last attempt was the following (for clarity, I removed the surrounding double-quotes and the curly brackets with the dollar — working just on the letter case):

${1}$<[1]: return $1.upper()>

But instead of MY_VARIABLE I get my_variableMY_VARIABLE.

Perhaps, the solution is obvious, but I cannot get it.

I did it! The solution found!

Before all, I have to say that I don’t count the solution as correct or corresponding to the ideas of the Gedit editor. It’s a dirty hack, of course. But, strangely, there is no way to change the initial content of placeholders in the snippets — haven’t I just found a standard way to do that?

So. If they don’t allow us to change the text in placeholders, let’s ask the system to do that.

The first thought that stroke me was to print backspace characters. There are two ways to do that: a shell script and a python script. The first approach might look like: $1$(printf '\b') The second one should do the same: $1$<[1]: return '\b'> But both of them don’t work — Gedit prints surrogate squares instead of real backspace characters.

Thus, xdotool is our friend! So is metaprogramming! You will not believe — metaprogramming in a shell script inside a snippet — sed will be writing the scenario for xdotool. Also, I’ve added a feature that changes spaces to underscores for easier typing. Here is the final code of the snippet:

$1$(
    eval \
        xdotool key \
            --delay 5 \
            `echo "${1}" | sed "s/./ BackSpace/g;"`
    echo "\"\${${1}}\"" \
        | tr '[a-z ]' '[A-Z_]'
)$0

Here are some explanations.

Usually, I never use backticks in my scripts because of some troubles and incompatibilities. But now is not the case! It seems Gedit cannot interpret the $(...) constructions correctly when they are nested, so I use the backticks here.

A couple of words about using the xdotool command. The most critical part is the --delay option. By default, it’s 12 milliseconds. If I leave it as is, there will be an error when the length of the text in the placeholder is quite long. Not to mention the snippet processing becomes slow. But if I set the time interval too small, some of the emulated keystrokes sometimes will be swallowed somewhere. So, five milliseconds is the delay that turns out optimal for my system.

At last, as I use backspaces to erase the typed text, I cannot use template parts outside the placeholder. Thus, such transformations must be inside the script. The complex heap after the echo command is what the template parts are.

What the last tr command does is the motivator of all this activity.

It turns out, Gedit snippets may be a power tool. Good luck!