Elan IDE Navigation

Entering and editing code in Elan/div>

Selecting the programming language(s)

TODO

Browse code

Watch the video: Browse code

The code shown in the editor has three types:

Instructions begin with a blue keyword as in:
variable namename? set to "Alice"value or expression?0namename? = "Alice"value or expression? # variable definition0var namename? = "Alice"value or expression?;0Dim namename? = "Alice"value or expression? ' variable definition0var namename? = "Alice"value or expression?;0
Comments are green and start with a hash # which is optionally followed by text:
# A program to investigate the Collatz Conjecturecomment?# A program to investigate the Collatz Conjecturecomment?// A program to investigate the Collatz Conjecturecomment?' A program to investigate the Collatz Conjecturecomment?public class Global { // A program to investigate the Collatz Conjecturecomment? }
The first comment in a file (which shows the software version) is automatically created and cannot be edited, deleted or moved.
new code prompts look like this:

or, when selected, like this:

and, on pressing Enter or right click, this menu appears:

which means that a second press of Enter will choose the (top) print option and a further Enter will supply the procedure call:
print(any) Code does not parse as Elan.print(any) Code does not parse as Elan.print(any) Code does not parse as Elan.print(any) Code does not parse as Elan.print(any) Code does not parse as Elan.
soliciting values and literals to be printed.
The reassign variable option inserts a setsetsetsetset instruction.
The initial letters shown in bold indicate the single letter that can be used from the keyboard for that instruction. Other instructions are entered by clicking on them in this menu.

Comments and new code prompts are not instructions. They do not alter the program's behaviour, though they are treated by the editor like instructions.

To select instructions

To...	Keyboard shortcut	Mouse gesture	Notes
select an arbitrary instruction		click on the initial keyword of the instruction or its number
select the next instruction	↓		limited to the current block of instructions
select the previous instruction	↑		limited to the current block of instructions
select the first instruction at the current level of indentation	Home
select the last instruction at the current level of indentation	End
select the outer instruction containing the current one	←
select the first inner instruction contained by the current one	→
add the next instruction to the current selection	Shift+↓	Shift, and click on the initial keyword of the instruction or its number	limited to the current block of instructions
add the previous instruction to the current selection	Shift+↑	Shift, and click on the initial keyword of the instruction or its number	limited to the current block of instructions
toggle outlining on an individual instruction	select the instruction then Ctrl+o	double-click on the initial keyword or instruction number
toggle outlining for the whole program	Ctrl+O (same as Ctrl+Shift+o)	click the outline button

Create new instructions

Watch the video: Create New Instructions

Edit instructions

Context menu

When you have selected an instruction by clicking on its keyword (turning its background blue), some immediate actions are available from its context menu which is opened either by clicking the right mouse button on the keyword, or by keying Ctrl+m. The commonest context menu shows these options, any one of which may then be clicked on to do the action:

The context menu shows only those actions which are relevant to that instruction in its context.

The following is a list all possible menu items with key equivalents where applicable:

do	undo	keyboard
insert new code below		Enter
insert new code above		Shift+Enter
delete		Ctrl+Delete or Ctrl+Backspace
move up		Ctrl+↑
move down		Ctrl+↓
cut for internal use		Ctrl+x
copy for internal use		Ctrl+c
ghost	unghost
set breakpoint	clear breakpoint

clear all breakpoints
copy for external use
make private	make public	Ctrl+p (toggle)

Select and edit a field

To...	Keyboard shortcut	Mouse gesture	Notes
select any field within an instruction		click anywhere on the text, or placeholder, for that field.	Text cursor will be placed at the end of the field
select the first field in a selected instruction	Tab
select the next field in the same instruction	Tab		will cycle through the fields and back to the whole instruction.
select the previous field in the same instruction	Shift+Tab		will cycle through the fields and back to the whole instruction.
select specific text within a field	Shift+← or →	click and drag across the desired characters
select all text within a field	Ctrl+a
position text-cursor at the start of a selected field	Home	click anywhere within the selected field
position text-cursor at the end of a selected field	End	click anywhere within the selected field
go from the last field to the next instruction	Enter

Insert a new instruction

If there is already a new code prompt where you want to insert an instruction, refer to the description under Browse code above.

Otherwise, select an instruction adjacent to where you want to add the new one and either:

key Enter to insert a new code prompt below it, or
key Shift+Enter to insert a new code prompt above it.

Delete ...

To delete	Keyboard shortcut	Notes
one or more (adjacent) existing instructions	select the instructions then Ctrl+Delete, Ctrl+Backspace or Ctrl+x	deleting a compound instruction will delete all its contained instructions
a just-created instruction	Backspace	this works only if no fields have been entered or 'child' instructions added
a new code prompt that is not needed	delete the same way as an instruction
all new code prompts	Click on the Trim button or Alt+t	removes all new code prompts except in places where further instructions are required (for example so as not to leave an empty loop)

Undo or redo a recent change

The editor retains previous versions of your code in its stack, but only when it has been parsed as valid. The code is saved internally, and also to file if auto-save is selected.

Action	Using the keyboard	Using the mouse
Undo previous changes	Ctrl+z	click on undo button
Redo previous undos	Ctrl+y	click on redo button

Move instructions up or down within the same block

Select the instructions, then key Ctrl+↓ or Ctrl+↑.
Movement is limited to up or down within the current code block.
To move instructions to a different code block use cut & paste. (It is not currently possible to move instructions using the mouse alone).

Cut and paste

To move one or more successive instructions to a new location within the program:
- Select the instructions to be cut, then key Ctrl+x.
- Create, or select, a new code prompt where you want to paste in the cut instructions.
- Key Ctrl+v to paste.
Note that the pasted instructions must be compatible with their new context, i.e. all of the instructions could have been created there in the first place. If they are incompatible, no paste will take place and you will see a pop-up advisory message. To restore the cut instructions to their original context, use undo.
To copy or move text between two fields in the program, or between program fields and external text:
Use the usual select highlight text (Ctrl+a for all of a field) and Ctrl+c to copy or Ctrl+x to cut, and then Ctrl+v to paste it in.

Ghosting

Instead of being able to 'comment out' code that you wish to retain but not execute, there is a method for 'ghosting' sections of code with much the same effect, while leaving the ghosted code fully formatted.

Select the single instruction (which may be a compound one, e.g. a while loop, an entire procedure or a test) to be ghosted.
Ctrl+m or right-click on the instruction keyword, and choose ghost from the context menu.
The instruction will be displayed in pale colours.
The ghosted code will then be ignored by the compiler and, for ghosted tests, by the test runner. This means, for example, that you can create two different implementations of the same function and compare them, as long as one of them is ghosted.
You can ghost code that does not compile, but you should not ghost code that does not parse: the ghosting will work, but you will not then be able to get the program as a whole to parse, and will have to unghost it again to fix it.
To restore a ghosted instruction, Ctrl+m or right-click on it and choose unghost.
Ghosted code can be copied, moved or deleted but, to edit ghosted code, you must unghost it first.
A program containing ghosted code can be saved.
Code containing ghosted instructions can be ghosted at a higher level, and remains ghosted when the higher level is unghosted.

Debugging programs

Watch the video: Debugging programs

You can debug a running program with or without having set breakpoints.

Run in debug mode, pause, and step

To...	Keyboard shortcut	Mouse gesture	Notes
debug a program, or resume debugging a paused program	Ctrl+g	Click on 'debug' button	disabled if there are any parse or compile issues.
pause a program that is running	Ctrl+u	Click on 'pause' button	enabled only when program is being debugged
step to the next instruction in a paused program	Ctrl+p	Click on 'step' button	enabled only then program is paused

Browsing named values

Whenever the program is paused, all named values (variables, parameters and constant values) that are currently in scope have their values automatically listed in the Info pane. This list may be browsed as follows:

To...	Keyboard shortcut	Mouse gesture
navigate to a specific line in the list when paused	Tab, Shift+Tab	Click on the line
expand/collapse a specific name within the list	Enter	Click on the + or - at the start of the line

Using breakpoints

Before clicking on debug you can set breakpoints at one or more instructions where you want execution to pause. A red flash symbol appears at every instruction that has a breakpoint defined..

When run using debug the program will automatically pause at every breakpoint, and the in-scope named values will be listed in the Info pane.

To...	Keyboard shortcut	Mouse gesture
set a breakpoint on a selected instruction	Ctrl+m on a selected instruction keyword then select set breakpoint	right-click for context menu, then select set breakpoint
clear existing breakpoints	Ctrl+m on a selected instruction keyword, then select clear breakpoint or clear all breakpoints	right-click for context menu, then select clear breakpoint or clear all breakpoints

Apple macOS specific

Where a keyboard shortcut is shown with the Ctrl control key, users of Apple's macOS should use the ⌘ Command key instead.

Colour scheme for CVD

There are two ways in which to change the colour scheme for users with CVD:

Button file has menu option preferences which offers an alternative colour scheme via a small dialogue. Whether or not you tick the CVD option, clicking confirm automatically tries to reload the web page, so you will receive a warning (which you can cancel) if you have unsaved code. You can also just press Escape to remove the dialogue.
The URL provided to a pupil may include a CVD scheme, as described above in Launch the IDE.