BBC BASIC for Windows
IDE and Compiler >> Integrated Development Environment >> TAB Key
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TAB Key
Post by mohsen on Nov 5th, 2008, 1:31pm

Why is the TAB key inactive in the IDE window? undecided

Re: TAB Key
Post by admin on Nov 5th, 2008, 3:42pm

Quote:
Why is the TAB key inactive in the IDE window?

What would you expect it to do? Indentation is automatic (and you're not allowed to have 'leading blanks' on a line) so it's not obvious to me what useful functionality it could have.

There's not even any way that TAB could insert the right number of spaces to align to a particular column (it would have to know by how much the line was going to be indented, which might depend on something after the TAB you haven't yet typed....).

I'm open to (practical) suggestions for something useful to do with that key, but I've not thought of anything up to now.

Richard.
Re: TAB Key
Post by mohsen on Nov 5th, 2008, 5:30pm

Here is an example:

Code:
      MS%=filestore%                    :REM MS%=memory start of file
      DS%=Offset%                       :REM DS%=address start for display
      REM PROCdebug(MS%)
      ME%=MS%+limit%                    :REM ME%=memory end of file
      DE%=DS%+limit%                    :REM DE%=address end of file for display
      M%=MS%                            :REM M%= current actual memory position
      D%=DS%                            :REM D%= current display Address position
      SMS%=MS%                          :REM SMS%=first memory address of 1st line of current screen
      SDS%=DS%                          :REM SDS%=first display address of 1st line of current screen
      SME%=SMS%+TotalLines%<<2          :REM SME%=last line of displayed (memory)
      SDE%=SDS%+TotalLines%<<2          :REM SDE%=last line of displayed (displayed)
      line%=0                           :REM start line
      VDU23,128,24,24,24,24,24,24,24,24 :REM define char 128
      PROCcreate_addresses
      PROConescreen(0,TotalLines%,SMS%,SDS%):PROCdisplay_pos


When writing a well documented and well commented code, you need that to be easily readable.

Currently the above space before the REM has to be inserted by hitting the space bar which is time consuming and counter-productive.

The TAB key has a purpose in all Editors. It is the first time I come across a Professional Programme Eitor that suggests that the TAB key is an accessory on the keyboard :)

You can define the TAB key to insert a default number of spaces say 8 (user configurable).
And, as a smart add-on to that, the TAB key will also move (by inserting spaces) to the position equal to the column of the previous line next colon ":" or semi-colon (in case of assembler) position. As stored tokens expand to different keyword lengths, the code to do the positioning is not staright forward as with plain text. But is doable and has been done before.

Re: TAB Key
Post by admin on Nov 5th, 2008, 10:13pm

Quote:
The TAB key has a purpose in all Editors.

It's had no purpose in the BB4W editor for more than seven years, and I can't remember anybody else having drawn attention to it!

Quote:
And, as a smart add-on to that, the TAB key will also move (by inserting spaces) to the position equal to the column of the previous line next colon ":" or semi-colon (in case of assembler) position.

As I explained, I believe that to be virtually impossible, not just difficult! To work out how many spaces to add it is necessary to know by how much the line will be indented. The amount by which it is indented may change as a result of something you type after pressing TAB.

So for that to work, either it needs a time machine to look into the future (!), or it would have to 'backtrack' and modify the number of inserted spaces after the rest of the line is typed.

Anyway, it's a moot point. The program editor is so complex and difficult (even for me) to understand, that I wouldn't dare make such a major alteration for fear of introducing a bug.

No doubt it would be possible (and relatively safe) to configure the TAB key to insert a fixed number of spaces (say 8) but it's not something I plan to do.

Richard.
Re: TAB Key
Post by admin on Mar 3rd, 2009, 09:24am

Quote:
No doubt it would be possible (and relatively safe) to configure the TAB key to insert a fixed number of spaces (say 8) but it's not something I plan to do

In BBC BASIC for Windows version 5.90a the TAB key can be programmed to execute an editor macro. A utility (SETTAB.BBC) is provided to program it to move the cursor to a specified column, with the proviso mentioned earlier in the thread that it won't work correctly if the indentation changes.

Richard.