2 new comment-like characters in Python to aid development?

[dbhbarton]

But all of them are clear on how they work: they affect one line, or have a

bracket style like /* */ and thus demark clearly what they affect. Even
someone not fluent in the language in question will quickly grab what they
mean.

There's nothing remotely fuzzy about how wip or halt comments would
work, nor anything unclear about what they would affect. Nor are they
remotely difficult to explain. They just haven't been employed before,
to my knowledge, even though the underlying effects seem to be a
reasonably common requirement.

But the key-difference is that the comment in python has a meaning for the
interpreter - ignore this.

OK that is true. But it's true for the halt comment as well.

The ? has no meaning. It only has a meaning for an editor.

So it _does_ have meaning! I'm sorry I just don't buy into this kind
of abstract programming ideology, and I never really have. I don't
care what the interpreter finds meaningful and neither, on a day to
day basis, do most users, I'm sure. It seems like the same kind of
aesthetic ideology that leads lots of programmers to feel repulsed by
Python's whitespace block delimiting. There's a more important
principle being missed by them: the human factor. The guy or gal who's
actually _using_ this stuff. BTW I don't mean to imply that you're not
thinking about human readability / useability, just that you don't
seem to be arguing from that basis.

Not in my opinion -
;p



Well, grab eric3, it's written in python, and teach it to do so! It's an
exercise in python then

I may do that. Thanks for bringing it to my attention.

I think you contradict yourself here. On the one side, you want it not
disturbing to the eye, yet it should be highlighted, so it will be directly
noticed by that same eyes.

You misread me. I wasn't talking about visual disturbance but 'code
disturbance'. Let me rephrase..
"..it would highlight without causing the highlighted code to be
ignored by the interpreter.."

it _is_ an disturbance. And with an IDE that stores such information in
e.g. project metainformation, you can even have the persistence, without
the disturbance and without altering python.

So it's fine and wonderful to add a massive chunk of code to IDEs to
introduce jargon-strewn behaviour that newbies have little hope of
comprehending yet alone taking advantage of, and which will inevitably
behave differently in any IDE that does get around to providing it?
But adding two special characters to the core language is 'messy'?

I can't argue with your aesthetic dislike of the proposed syntax, it's
just the reasoning you use to support your stance that doesn't ring
true to me! (I trust no offense is caused.)

 

[Diez B. Roggisch]

So it _does_ have meaning! I'm sorry I just don't buy into this kind
of abstract programming ideology, and I never really have. I don't
care what the interpreter finds meaningful and neither, on a day to
day basis, do most users, I'm sure. It seems like the same kind of
aesthetic ideology that leads lots of programmers to feel repulsed by
Python's whitespace block delimiting. There's a more important
principle being missed by them: the human factor. The guy or gal who's
actually _using_ this stuff. BTW I don't mean to imply that you're not
thinking about human readability / useability, just that you don't
seem to be arguing from that basis.

I certainly do. Because a comment is always a comment. If you happen to
have a multi-line comment (in python that is) that spans more than a
page of your current terminal, you clearly will see it as such when
piped through less - a frequent tool for looking into code of libraries
for example. At least for me, and I guess some other coders as well.

But a tiny ? or !, the latter one massively changing the semantics of
the displayed code? I'm not too positive that this will be getting the
proper attention needed when comprehending the code.

Even the multiline-comments of C are easier, because they feature an
end-mark. Which for one _is_ easier to implement, thus even "less" might
implement some syntax hi-lighting based on it (if the terminal supports
that, that is. I've been doing my fair share of last-minute hacking
through malconfigured ssh-connections in vi, no syntax-highlighting
whatsoever) - while it is much less probable that "less" will grow a
full blown python parser just for the sake of hi-lighting a !-prefixed
block of code.


FWIW, I'm totally convinced that the addition of this feature to the
interpreter itself would be a minor operation that wouldn't cause much
headache from a implementation POV. It's just I don't buy into its
usefulness.

You misread me. I wasn't talking about visual disturbance but 'code
disturbance'. Let me rephrase..
"..it would highlight without causing the highlighted code to be
ignored by the interpreter.."

What do you mean by code-disturbance? Programming is usually something
that needs carefully assembled sequences of characters, with some
seemingly minor interpunction characters becoming extremly meaningful.
And you want to add to that the complexity of something that has _no_
meaning at all - for the language. To me that is a disturbance. Clearly
a matter of taste, though.

So it's fine and wonderful to add a massive chunk of code to IDEs to
introduce jargon-strewn behaviour that newbies have little hope of
comprehending yet alone taking advantage of, and which will inevitably
behave differently in any IDE that does get around to providing it?
But adding two special characters to the core language is 'messy'?

Adding two characters to the language from which one's only purpose is
to support the introduction of jargon-strewn behavior that newbies have
little hope of comprehending let alone taking advantage of, and which
will inevitable behave differently in any IDE that does get around
providing it.

I couldn't say it better. It is exactly my point: the ? is _nothing_
without an IDE, where _none_ of them is forced to interpret and
represent it by any means. Yet still you want to add it? Sorry, I can't
buy that.

Besides, the whole purpose of IDEs is to add massive chunks of code to
e.g. analyze class structures, show syntactic errors even before the
code is run and so on... so if you accept that editing code is more than
poking with a hex editor on your hard disk image, I fail to see the
problem of adding such chunks of code if it is feasible.

I can't argue with your aesthetic dislike of the proposed syntax, it's
just the reasoning you use to support your stance that doesn't ring
true to me! (I trust no offense is caused.)

Certainly not. And I don't intend to cause offense myself!

Diez

 

[Jerry Hill]

However python 2.5,
except OperationalError:
responds with
"OperationalError" is not defined.

I believe that needs to be spelled
except sqlite3.OperationalError:
do_something()

 

[jim-on-linux]

pyhelp,

I set up a table in SQLite3.

While running other modules I want to know if a
table exists.

SQL has a command "List Tables" but I don't think
SQLlite3 has this command.

I've tried
cursor.execute("select * from debtor where key
is not null ")

The table debtor does not exist so I get
"OperationalError"
which I want to trap with try/except or some other
way.

However python 2.5,
except OperationalError:
responds with
"OperationalError" is not defined.

Ideas on how to determine if a table exists would
be welcome.

jim-on-linux

 

[jim-on-linux]

I believe that needs to be spelled
except sqlite3.OperationalError:
do_something()

Thanks,
except sqlite3.OperationalError:
works for me.

jim-on-linux

 

[Matthew Woodcraft]

Thanks you both.

For what it's worth, sufficiently recent versions of emacs python-mode
have this built in.

-M-

 

[Robert Marshall]

For what it's worth, sufficiently recent versions of emacs
python-mode have this built in.

Is this with xemacs python mode or have you downloaded python mode
separately from emacs? I've got the latest emacs cvs (well a week
old) and it doesn't have it, or is it very,very recent?

Robert

 

[Bjoern Schliessmann]

But # is 'only a comment sign' as well, and equally meaningless to
the interpreter.

No! "#" means "disregard everything until EOL" to the interpreter.
Your proposed highlighting character means exactly nothing to the
interpreter. Get the difference?

But it's still part of the language, very very
useful and I profit from its existence every day.

See above, comment tokens do have syntactical meaning.

If you can highlight an entire block with a single character,
won't there be _less_ visual clutter than the current way of
achieving the same effect with # comments?

You can't "highlight" something with comments. It will become a
comment and not be executed.

Some editors may display comments in a different manner, yes. But
that's not what comments are for -- the different display is just
for convenience.

Would if I could!

Why don't you grab a good editor ...

What we're talking about here is a form of 'alternate commenting
style'. With the IDE's cooperation it'd work on whole blocks at
once,

I know editors that can select blockwise without any special
characters in the source, just by keystrokes ...

it would highlight without disrupting the code concerned (at
least the way I'm envisaging it), it would be versatile (could
probably be used for as big a variety of purposes as the #
comment),

Any kind of highlighting is absolutely different from comments.

and yes, it'd be persistent, which is how it would be
different from any IDE-based highlighting.

(Why shouldn't other ways of highlighting be persistent? Metadata
exists.)

I think that'd be most useful. You don't. So far nobody else here
does either, and I've not persuaded anybody differently. Fair
enough!

Agreed.

Regards,


Björn

P.S.: More and more I'm getting the impression that everybody should
first learn to program with a most simple editor. The typical
Java+Eclipse start is wrong, IMHO ...

 

[paul]

pyhelp,

I set up a table in SQLite3.

While running other modules I want to know if a
table exists.

SQL has a command "List Tables" but I don't think
SQLlite3 has this command.

I think "list tables" is a mysqlism

I've tried
cursor.execute("select * from debtor where key
is not null ")

FROM sqlite_master SELECT name WHERE type='table';

cheers
Paul

 

[Paddy]

I use # FIXME for this purpose or /* FIXME */ in C etc.

I have an emacs macro which shows it up in bright red / yellow text so
it is easy to see and the company has a system which makes a web page
with a list of all the FIXMEs on.

FIXME is easy to grep for, language neutral and a lot of people use
something similar (eg XXX or TODO).


You can so this with triple quotes. ''' and ''' (if you normally use
""" """ for docstrings)

Python just ignores strings that lie around.

Vim will highlight the following comments too:
#FIXME
#TODO
#XXX

- Paddy