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EdimCoder's Improvements Over Ed
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While EdimCoder takes a lot of inspiration from Ed, it also
makes several improvements over Ed. Before we move onto
detailing a new type of editor that was used in the past,
I've decided to go over these improvements.
Prompts and Colors
One Improvement made over Ed is that EdimCoder utilizes
prompts and colors to distinguish file text from the
editor's user interface. Additionally, prompts give useful
information and are especially helpful to new users.
I made the choice to include both colors and prompts for
the reasons above, but also because EdimCoder no longer
needs to be restricted by the hardware that was used when
Ed was created/used (namely, teletypes). Because screens
can display characters much quicker now than in the past,
showing prompts and colors should no longer be a bother
considering speed.
The SubEditor
Many command-based editors have a SubEditor. This is
the line editor that you use to type in a command or a
line. Therefore, subeditors work similarly to how readline
and linenoise work. Previously we discussed how EdimCoder
created it's own alternative to readline that is portable
across Windows, Linux, and perhaps in the future, others.
This readline alternative is the SubEditor. It provides
the means of editing the command line or the line you are
currently typing to insert, append, prepend, or replace
in the file.
EdimCoder made several improvements to it's subeditor
over Ed. These include the ability to move the cursor
left/right so it's positioned in the middle of the text
of the current line, and the ability to add text in the
middle/beginning of the line where the cursor is currently
positioned. Additionally, the Home, End, and Delete keys
also work. And finally, the Tab key always inserts a tab
character, but will display as 4 spaces instead of a tab
so that the tab stops of the terminal aren't used.
Context
One of the problems I considered while creating EdimCoder
was how someone could make sure they have the context of
what they are writing in mind. This means you should have
a good idea of where you are currently doing an operation,
making sure you are doing the *right* operation, and where
in the file the operation is happening.
Therefore, I have came up with a few different features
that help you get an idea of all of these things. Firstly,
the simplest is always showing the current line number you
are on while doing an operation and showing the current
line number in the command prompt. Additionally, there is
a 1 character gutter that shows the current operation you
are applying to the line number you are currently on. This
character is often the same as the command you used. I have
provided the different characters that may be shown below:
a - for inserting lines after a line
A - for inserting chars at beginning of line
i - for inserting lines before a line
I - for inserting chars at end of line
x - for deleting line
^ - the line *was* moved up - meaning it was previously in
a position lower than it currently is.
V - the line *was* moved down - meaning it was previously
in a position lower than what it currently is.
r - the line is being replaced
R - a given subset of the line is being replaced
(replacing chars with chars)
Whenever you are inserting, deleting, or moving lines, ^
and V are used to show the effects those commands have on
the other lines of the file. In most instances only the
first moved line is shown. For example, inserting one line
before another will show that the line being inserted
before was moved down one line number to accommodate
for the insertion. Therefore, 'V' will be shown in the
gutter of that line after you are done with the insertion
operation.
The next feature is a very simple one. EdimCoder will
display the line before and the line after the line(s)
you are currently operating on to give more context on
where in the file the operation is happening.
The final feature is incomplete and only works for *few*
files because it is programming-language aware. The feature
is the ability to show an outline of the file (using the
'info' command). This outline currently works with C, C/C++
Headers, and Markdown files. This provides more context
as well as, in the future, the ability to more easily jump
to these locations and do operations *on* these "objects"
(for example, doing an operation on a function or section).
Bookmarks
This is a recent addition. EdimCoder has the ability to
store line numbers and line ranges in bookmarks (which
are basically like variables). Then, you can use these
bookmarks in any of the operations. Here's an example of
creating a bookmark, then using it in the Print operation:
d 5:25 fGetInput
P #fGetInput
This will set lines 5 through 25 to the 'fGetInput'
bookmark. Then, when passed into the Print operation,
it will print out lines 5 through 25.
In the future, different types of bookmarks will be
provided. More on this in a future post.
Command Modes
EdimCoder also has different modes - currently 3 modes
(but more in the future). Ed can be thought of as
having 2 modes, command and input. EdimCoder has the
same modes, plus an additional one: the preview mode. The
preview mode acts similar to 'pg' (or less but being less
screen-oriented) and accepts commands that tell it whether
you want to view the previous or next page. EdimCoder will
be getting at least one additional mode in the future. More
on this in a future post.
Canceling Current Operation
EdimCoder lets you cancel the current operation by
pressing Ctrl-X. This will revert back to what the
text was before the operation ever happened.
Buffers
EdimCoder has one more improvement over Ed - this one I
consider to be a big improvement. EdimCoder has the ability
to open multiple files/buffers and easily switch between
them. The current line, outline, and other information is
kept per-buffer.
Continually Improving
While EdimCoder currently offers many advantages and
improvements over Ed, it is continually improving. There
are various other ideas that will be implemented in
the future (hints: input suspension, outline bookmarks,
relative lines, relative and static bookmarks, default
bookmarks, ...). Thanks for reading this post. Hopefully
I will have the next post out soon, which will talk about
a different type of editor used in the past and how it's
ideas can be used in EdimCoder.