Alternate indent proposal for python 3000

[Eric Wertman]

I was considering putting together a proposal for an alternate block
syntax for python, and I figured I'd post it here and see what the
general reactions are. I did some searching, and while I found a lot
of tab vs space debates, I didn't see anything like what I'm thinking
of, so forgive me if this is a very dead horse.

Generally speaking, I like the current block scheme just fine. I use
python on a daily basis for system administration and text parsing
tasks, and it works great for me.

From time to time, though, I find myself needing a language for server-
side includes in web pages. Because of the need to indent (and
terminate indents), python seems an awkward choice for this, and it's
easy for me to see why php and perl are more popular choices for this
kind of task. Perhaps this is just my perception though.

I feel that including some optional means to block code would be a big
step in getting wider adoption of the language in web development and
in general. I do understand though, that the current strict indenting
is part of the core of the language, so... thoughts?

[Christian Heimes]

Eric Wertman schrieb:

I was considering putting together a proposal for an alternate block
syntax for python, and I figured I'd post it here and see what the
general reactions are. I did some searching, and while I found a lot
of tab vs space debates, I didn't see anything like what I'm thinking
of, so forgive me if this is a very dead horse.

You are definitely too late to propose a change for py3k.

I feel that including some optional means to block code would be a big
step in getting wider adoption of the language in web development and
in general. I do understand though, that the current strict indenting
is part of the core of the language, so... thoughts?

Why should Python repeat the mistakes other languages did with SSI or
<?php ?inline code? Python favors the MVC separation of code and layout.

Christian

[George Sakkis]

On Apr 20, 11:35*am, Eric Wertman <ewert...@gmail .comwrote:

I was considering putting together a proposal for an alternate block
syntax for python, and I figured I'd post it here and see what the
general reactions are. *I did some searching, and while I found a lot
of tab vs space debates, I didn't see anything like what I'm thinking
of, so forgive me if this is a very dead horse.

[with apologies to Monty Python]

This horse is no more! He has ceased to be! 'E's expired and gone to
meet 'is maker! 'E's a stiff! Bereft of life, 'e rests in peace! THIS
IS AN EX-HORSE!!

:)

Generally speaking, I like the current block scheme just fine. *I use
python on a daily basis for system administration and text parsing
tasks, and it works great for me.

From time to time, though, I find myself needing a language for server-
side includes in web pages. *Because of the need to indent (and
terminate indents), python seems an awkward choice for this, and it's
easy for me to see why php and perl are more popular choices for this
kind of task. *Perhaps this is just my perception though.

Look into any of the dozen Python-based template engines that are
typically used for such tasks; they offer many more features than a
way to indent blocks.

George

[Eric Wertman]

Look into any of the dozen Python-based template engines that are
typically used for such tasks; they offer many more features than a
way to indent blocks.

George

I definitely will.. could you throw out some examples though?
Thanks!

Eric

[Matthew Woodcraft]

Christian Heimes <li***@cheimes. dewrote:

>I feel that including some optional means to block code would be a big
step in getting wider adoption of the language in web development and
in general. I do understand though, that the current strict indenting
is part of the core of the language, so... thoughts?

Why should Python repeat the mistakes other languages did with SSI or
<?php ?inline code? Python favors the MVC separation of code and layout.

An alternative scheme for describing the block structure could be
useful in other cases, though. For example, if you wanted to support
putting snippets of Python in configuration files, or spreadsheet
cells.

There's no need to support the new scheme in .py files, so it seems to
me that this doesn't have to be done in the core language. All that's
needed is a variant of 'eval' which expects the alternate scheme, and
that could be prototyped just using text manipulation and the normal
'eval'.

If someone wrote a library for this and it proved popular, I expect it
would be considered for the standard library.

-M-

[Arnaud Delobelle]

On Apr 20, 5:42*pm, Matthew Woodcraft
<matth...@chiar k.greenend.org. ukwrote:

Christian Heimes *<li...@cheimes .dewrote:

I feel that including some optional means to block code would be a big
step in getting wider adoption of the language in web development and
in general. *I do understand though, that the current strict indenting
is part of the core of the language, so... thoughts?

Why should Python repeat the mistakes other languages did with SSI or
<?php ?inline code? Python favors the MVC separation of code and layout.

An alternative scheme for describing the block structure could be
useful in other cases, though. For example, if you wanted to support
putting snippets of Python in configuration files, or spreadsheet
cells.

There's no need to support the new scheme in .py files, so it seems to
me that this doesn't have to be done in the core language. All that's
needed is a variant of 'eval' which expects the alternate scheme, and
that could be prototyped just using text manipulation and the normal
'eval'.

By 'eval', I guess you mean 'exec' :)

--
Arnaud

[Matthew Woodcraft]

Arnaud Delobelle <ar*****@google mail.comwrote:

By 'eval', I guess you mean 'exec' :)

Yes. Shows how often I use either.

-M-

[Terry Reedy]

"Matthew Woodcraft" <ma******@chiar k.greenend.org. ukwrote in message
news:X0*******@ news.chiark.gre enend.org.uk...
| There's no need to support the new scheme in .py files, so it seems to
| me that this doesn't have to be done in the core language. All that's
| needed is a variant of 'eval' which expects the alternate scheme, and
| that could be prototyped just using text manipulation and the normal
| 'eval'.

Eval() is for expressions, exec() is for general code. But you do not
really need a variant. Just define a preprocessor function 'blockify'
which converts code in an alternate syntax to regular indented block
syntax. Then

exec(blockify(a lt_code_string) )

I presume that this is more or less what the templating engines do.

[Gabriel Genellina]

En Sun, 20 Apr 2008 13:42:05 -0300, Matthew Woodcraft <ma******@chiar k.greenend.org. ukescribió:

An alternative scheme for describing the block structure could be
useful in other cases, though. For example, if you wanted to support
putting snippets of Python in configuration files, or spreadsheet
cells.
[...] If someone wrote a library for this and it proved popular, I expect it
would be considered for the standard library.

There is "pindent.py " in the Tools/scripts directory:

# ... When called as "pindent -r" it assumes its input is a
# Python program with block-closing comments but with its indentation
# messed up, and outputs a properly indented version.

# A "block-closing comment" is a comment of the form '# end <keyword>'
# where <keywordis the keyword that opened the block ...

def foobar(a, b):
if a == b:
a = a+1
elif a < b:
b = b-1
if b a: a = a-1
# end if
else:
print 'oops!'
# end if
# end def foobar

--
Gabriel Genellina

[Matthew Woodcraft]

Terry Reedy <tj*****@udel.e duwrote:

But you do not really need a variant. Just define a preprocessor
function 'blockify' which converts code in an alternate syntax to
regular indented block syntax. Then

exec(blockify(a lt_code_string) )

You can do it like that, but if it were to become part of the standard
distribution it would be nice to avoid having to tokenise the code
twice. (You could define the new block scheme in such a way that
'blockify' doesn't need to tokenise, but I think it would end up a bit
ugly.)

-M-