[Lazarus] Collapsible try...finally...except...end blocks idea

[el_es via Lazarus]

Hi,

this idea may need further refining, but it may be easier to handle
in Lazarus source editor, than in the compiler, where it was
originally posted.

In short, to have the nested try...finally/except...end; blocks display
in a single tier flatter manner, like

try
try
code block 1;
finally
code block 2;
end;
except
code block 3;
end;

display in Lazarus like

try
code block 1;
finally
code block 2;
except
code block 3;
end;

with similar handling like the collapsible code blocks (e.g. a [+] or [-] on the gutter next to all the try's,
depending on what the default setting is, to display or not to display nested try blocks)
and handling of more 'sophisticated' nests like try...except...finally...except...end;

(that means, in raw source code, this still will display like nested try blocks, not flat,
and as such be fed into the compiler).

This being handled in Lazarus would mean, that it would work in ANY compiler mode selected
(regardless if it's Delphi or not) and the benefits of flatter display of the code blocks
would really show (like making it harder to enter code blocks where they normally don't go in such constructs,
and helping to catch errors made like that - e.g. if someone consciously needed to put code in places it
does not normally go, collapsing the construct would not work).

It was met with resistance in the FPC mailing lists, and then it was dropped there;
I can't say I don't agree with /some/ of their arguments actually.

Hope this would actually make more sense here :) as a coding tool.

Kind Regards

el es

--

[Martin Frb via Lazarus]

Post by el_es via Lazarus
In short, to have the nested try...finally/except...end; blocks display
in a single tier flatter manner, like
try
try
code block 1;
finally
code block 2;
end;
except
code block 3;
end;
display in Lazarus like
try
code block 1;
finally
code block 2;
except
code block 3;
end;
with similar handling like the collapsible code blocks (e.g. a [+] or [-] on the gutter next to all the try's,
depending on what the default setting is, to display or not to display nested try blocks)
and handling of more 'sophisticated' nests like try...except...finally...except...end;
(that means, in raw source code, this still will display like nested try blocks, not flat,
and as such be fed into the compiler).

I dont think the code editor will change the indent, for that there are
code formatters. (jedi)

Display a different indent from what is actually in the text brings up
new issues, such as what happens if you edit spaces in the virtual
indent. Where to they go in the real text?
Despite this, I am not convinced it is should be included. But if
someone wants to do a package that install such a feature.....

Anyway the compiler already supports the indent you want (the compiler
does not care about indent), so you can actually write it like this.

try try
code block 1;
finally
code block 2;
end;
except
code block 3;
end;

All you have to deal with are:
- the double "try".
- the extra "end"

Several solutions

** 1)
Use fpc macro support (look up exact syntax, I am writing this from (distant) memory)
(this of course will trouble the editors folding detecting and outlining-markup)

{$macro on}
{$define try2:= try try}
{$define thenExcept := end; except}

try2
code block 1;
finally
code block 2;
thenExcept
code block 3;
end;

The macro solution also makes it visually clear that you did not forget an opening try. After all it could be that there is an except block that covers a wider amount of code...

** 2)
Or (and that could be added to the editor):
Have a /hide option for {%region} (same as the current /fold). With /hide the region would be default disappear.

try
{%region /hide}try{%endregion}
code block 1;
finally
code block 2;
{%region /hide}end;{%endregion}
except
code block 3;
end;




--

[el_es via Lazarus]

Post by Martin Frb via Lazarus

Post by el_es via Lazarus
In short, to have the nested try...finally/except...end; blocks display
in a single tier flatter manner, like
try
   try
     code block 1;
   finally
     code block 2;
   end;
except
   code block 3;
end;
display in Lazarus like
try
   code block 1;
finally
   code block 2;
except
   code block 3;
end;
with similar handling like the collapsible code blocks (e.g. a [+] or [-] on the gutter next to all the try's,
depending on what the default setting is, to display or not to display nested try blocks)
and handling of more 'sophisticated' nests like try...except...finally...except...end;
(that means, in raw source code, this still will display like nested try blocks, not flat,
and as such be fed into the compiler).

I dont think the code editor will change the indent, for that there
are code formatters. (jedi)

Code formatters would always work on the 'unfolded'/'raw' code anyway.
This feature would only be about how to display it.

Post by Martin Frb via Lazarus
Display a different indent from what is actually in the text brings
up new issues, such as what happens if you edit spaces in the virtual
indent. Where to they go in the real text?

If we treat the left-most column of the code block in question as base line,
then I think adding spaces to other lines in the block would not be that much of a problem.

Post by Martin Frb via Lazarus
Despite this, I am not
convinced it is should be included. But if someone wants to do a
package that install such a feature.....

This is merely an idea submission in hope that someone likes it enough
to make it, and take all the credit for it (I do not mind).

Post by Martin Frb via Lazarus
Anyway the compiler already supports the indent you want (the
compiler does not care about indent), so you can actually write it
like this.
try try
  code block 1;
finally
  code block 2;
end;
except
  code block 3;
end;
- the double "try".
- the extra "end"

And the possibility that someone might insert code between end; and except;
Or anywhere in between the 'try' keywords.
Now this is not a big problem in this case, because there may be valid usage of that.

If the code display formatter finds this one out, it will refuse to fold and reindent the block,
that should then be enough of an indication for the programmer, that this has happened.

Post by Martin Frb via Lazarus
 
Several solutions
** 1)
Use fpc macro support (look up exact syntax, I am writing this from (distant) memory)
(this of course will trouble the editors folding detecting and outlining-markup)
{$macro on}
{$define try2:= try try}
{$define thenExcept := end; except}
try2
  code block 1;
finally
  code block 2;
thenExcept
  code block 3;
end;

I'd name that last macro 'endExcept' maybe, but...

Post by Martin Frb via Lazarus
The macro solution also makes it visually clear that you did not
forget an opening try. After all it could be that there is an except
block that covers a wider amount of code...
** 2)
Or (and that could be added to the editor): Have a /hide option for
{%region} (same as the current /fold). With /hide the region would be
default disappear.
try
{%region /hide}try{%endregion}
  code block 1;
finally
  code block 2;
{%region /hide}end;{%endregion}
except
  code block 3;
end;

... I guess I like the second ({%region hide}) way better than the macros,
because with macros you're inventing the whole new set of keywords for
this; The only problem with this region directive is that it would
mess up the formatting for non-Lazarus editors, and also, how will it
behave after the JCF is used?

Thanks for your reply :)

el_es

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