Another scripting language implemented into Python itself?

[Quest Master]

I am interested in developing an application where the user has an
ample amount of power to customize the application to their needs, and
I feel this would best be accomplished if a scripting language was
available. However, I want to code this application in Python, and I
have not yet heard of an implementation of another scripting language
into Python.

An example of what I mean is this (an implementation of Lua into Ruby
-- which I'd prefer not to use): http://ruby-lua.unolotiene.com/

I know C/C++ might be better suited for a task of this kind, but most
of the modules in my application which need speed have already been
coded in C++. I want to use Python as the "glue" for this project;
writing an entire application with a pretty GUI is not fun, as most of
you may know from previous experience.

So, my question is simply this: is there an implementation of another
scripting language into Python?

[Roy Smith]

Re: Another scripting language implemented into Python itself?

In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
Quest Master <zainalam@gmail .com> wrote:
[color=blue]
> I am interested in developing an application where the user has an
> ample amount of power to customize the application to their needs, and
> I feel this would best be accomplished if a scripting language was
> available. However, I want to code this application in Python, and I
> have not yet heard of an implementation of another scripting language
> into Python.
>
> An example of what I mean is this (an implementation of Lua into Ruby
> -- which I'd prefer not to use): http://ruby-lua.unolotiene.com/
>
> I know C/C++ might be better suited for a task of this kind, but most
> of the modules in my application which need speed have already been
> coded in C++. I want to use Python as the "glue" for this project;
> writing an entire application with a pretty GUI is not fun, as most of
> you may know from previous experience.
>
> So, my question is simply this: is there an implementation of another
> scripting language into Python?[/color]

Python *is* a scripting language. Why not just let your users write
Python modules which you them import and execute via some defined API?

[Jeff Shannon]

Re: Another scripting language implemented into Python itself?

Roy Smith wrote:
[color=blue]
> In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
> Quest Master <zainalam@gmail .com> wrote:
>[color=green]
>>So, my question is simply this: is there an implementation of another
>>scripting language into Python?[/color]
>
> Python *is* a scripting language. Why not just let your users write
> Python modules which you them import and execute via some defined API?[/color]

Because you cannot make Python secure against a malicious (or
ignorant) user -- there's too much flexibility to be able to guard
against every possible way in which user-code could harm the system.
Parsing your own (limited) scripting language allows much better
control over what user-code is capable of doing, and therefore allows
(at least some measure of) security against malicious code.

To the O.P.: Yes, people have implemented other languages in Python.
For example, I believe that Danny Yoo has written a Scheme
interpreter in Python (Google tells me it should be at
http://hkn.eecs.berkeley.edu/~dyoo/python/pyscheme but I'm getting no
response from that host right now), but I don't know whether Scheme
counts as a scripting language. ;)

However, if you're using a fully-featured language for these user
scripts, you'll probably have the same security issues I mentioned for
Python. Unless you really need that level of features, you may be
better off designing your own limited language. Check into the docs
for pyparsing for a starter...

Jeff Shannon
Technician/Programmer
Credit International

[Terry Reedy]

Re: Another scripting language implemented into Python itself?


"Roy Smith" <roy@panix.co m> wrote in message
news:roy-97DBC5.19403124 012005@reader1. panix.com...[color=blue]
> In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
> Quest Master <zainalam@gmail .com> wrote:
>[color=green]
>> So, my question is simply this: is there an implementation of another
>> scripting language into Python?[/color]
>
> Python *is* a scripting language. Why not just let your users write
> Python modules which you them import and execute via some defined API?[/color]

That was my thought also, with the note that you only need to document as
much users will need, including specific modules (if any) to import.

Terry J. Reedy

[Rocco Moretti]

Re: Another scripting language implemented into Python itself?

Roy Smith wrote:[color=blue]
> In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
> Quest Master <zainalam@gmail .com> wrote:
>[color=green]
>>So, my question is simply this: is there an implementation of another
>>scripting language into Python?[/color]
>
> Python *is* a scripting language. Why not just let your users write
> Python modules which you them import and execute via some defined API?[/color]

I can think of a couple of reasons off the top of my head:

The OP doesn't mention his application, but there is something to be
said about domain specific scripting languages. A well designed
domain-specific scripting language(*) with the appropriate high level
constructs can make script writing simpler.

There's also an audience factor. Python is easy to learn, but it's still
a programming language. A well designed domain-specific scripting
language(*) can make it very easy to get work done in a particular case
without having to learn the Python mind frame. (How assignments work,
mutable/immutable, Python's call passing system, etc.)

Python's also dangerous. Every time you do an "import module", you put
your system at risk of crashing, having the hard-drive wiped, sending
incorrect signal codes to peripherals, etc. A well-designed specialty
language(*) minimizes those risks - don't need disk access? Don't allow
it in your language.

There's also the valuable learning experience of designing and
implementing a scripting language.

(*) Note that I keep saying "well-designed". A poorly designed scripting
language is very bad - you can feel shackled by the restrictions it
imposes, and find yourself unable to do what you want without laborious
contortions, if at all. I also say "domain specific" because, at this
time, there are enough general purpose scripting languages that you are
likely to find what you need already existing, unless you are
experimeting with a completely new programing paradigm.

To answer the OP's question:

Yes - sort of. Currently work is underway to implement the Python
scripting language in Python. Cleverly called "PyPy", the website is
"http://www.codespeak.n et/pypy".

[Roy Smith]

Re: Another scripting language implemented into Python itself?

Rocco Moretti <roccomoretti@h otpop.com> wrote:[color=blue]
> The OP doesn't mention his application, but there is something to be
> said about domain specific scripting languages. A well designed
> domain-specific scripting language(*) with the appropriate high level
> constructs can make script writing simpler.[/color]

This is a bit of a sore point with me.

I've been involved with several projects where people felt the need to
invent their own scripting languages. It usually starts with "we don't
need the power of a full programming language, we only need to be able
to do X, Y, and Z". So they write a little language which lets them do
X, Y, and Z.

Then they discover they need more complex data structures than they
originally thought. And nested loops. And functions. And more
sophisticated variable scoping rules. And a regex library. And 47
other things. So they duct-tape all those into the system.

A few years later, you end up with most of a real programming language,
except with a whole bunch of warts.

The syntax is usually quirky (the one I'm working with today does not
allow any space before the open paren of a function call, but requires
it before the opening paren of an "if" statement). It generally has
poor error reporting. It doesn't have the whole family of free tools
that grow up around any real language (editor customization packages,
syntax checkers, debuggers, extensions, etc). You doesn't have a gaggle
of tutorial books written about it that you can buy from your favorite
on-line bookseller.

Worse, when you need more brains/bodies on the project, you can't put an
add on Hot Jobs for "experience d OurOwnScripting Language programmer" and
expect to get anybody who can be productive quickly.

What it does have is a body of code dependent on it which is now so
large that porting it to something else is an unthinkably large task.
And it's got a small cadre of language gurus who spend all day defending
the language with answers like, "But, it was never *intended* that
people would do stuff like this with it".

Anyway, that's my little rant on inventing your own scripting language.
Imbed Python, or Perl, or TCL, or Ruby, or PHP, or Java, or whatever
floats your boat. Almost any choice has got to be better than rolling
your own. Invest your intellectual capital doing what you can do best,
and don't get bogged down developing a new language.

[Jack Diederich]

Re: Another scripting language implemented into Python itself?

On Mon, Jan 24, 2005 at 09:17:24PM -0500, Roy Smith wrote:[color=blue]
> Rocco Moretti <roccomoretti@h otpop.com> wrote:[color=green]
> > The OP doesn't mention his application, but there is something to be
> > said about domain specific scripting languages. A well designed
> > domain-specific scripting language(*) with the appropriate high level
> > constructs can make script writing simpler.[/color]
>
> This is a bit of a sore point with me.
>
> I've been involved with several projects where people felt the need to
> invent their own scripting languages. It usually starts with "we don't
> need the power of a full programming language, we only need to be able
> to do X, Y, and Z". So they write a little language which lets them do
> X, Y, and Z.
>
> Then they discover they need more complex data structures than they
> originally thought. And nested loops. And functions. And more
> sophisticated variable scoping rules. And a regex library. And 47
> other things. So they duct-tape all those into the system.
>
> A few years later, you end up with most of a real programming language,
> except with a whole bunch of warts.
>
> The syntax is usually quirky (the one I'm working with today does not
> allow any space before the open paren of a function call, but requires
> it before the opening paren of an "if" statement). It generally has
> poor error reporting. It doesn't have the whole family of free tools
> that grow up around any real language (editor customization packages,
> syntax checkers, debuggers, extensions, etc). You doesn't have a gaggle
> of tutorial books written about it that you can buy from your favorite
> on-line bookseller.
>
> Worse, when you need more brains/bodies on the project, you can't put an
> add on Hot Jobs for "experience d OurOwnScripting Language programmer" and
> expect to get anybody who can be productive quickly.
>
> What it does have is a body of code dependent on it which is now so
> large that porting it to something else is an unthinkably large task.
> And it's got a small cadre of language gurus who spend all day defending
> the language with answers like, "But, it was never *intended* that
> people would do stuff like this with it".
>[/color]

Me Too!
I mean, did you used to work at CDNOW too?
I don't miss that want-to-gouge-out-your-own-eyes feeling.

-Jack

[Bob Smith]

Re: Another scripting language implemented into Python itself?

Rocco Moretti wrote:
[color=blue]
> Python's also dangerous. Every time you do an "import module", you put
> your system at risk of crashing, having the hard-drive wiped[/color]

Have you been drinking again?

[Carl Banks]

Re: Another scripting language implemented into Python itself?

Roy Smith wrote:[color=blue]
> Rocco Moretti <roccomoretti@h otpop.com> wrote:[color=green]
> > The OP doesn't mention his application, but there is something to[/color][/color]
be[color=blue][color=green]
> > said about domain specific scripting languages. A well designed
> > domain-specific scripting language(*) with the appropriate high[/color][/color]
level[color=blue][color=green]
> > constructs can make script writing simpler.[/color]
>
> This is a bit of a sore point with me.
>
> I've been involved with several projects where people felt the need[/color]
to[color=blue]
> invent their own scripting languages. It usually starts with "we[/color]
don't[color=blue]
> need the power of a full programming language, we only need to be[/color]
able[color=blue]
> to do X, Y, and Z". So they write a little language which lets them[/color]
do[color=blue]
> X, Y, and Z.
>
> Then they discover they need more complex data structures than they
> originally thought. And nested loops. And functions. And more
> sophisticated variable scoping rules. And a regex library. And 47
> other things. So they duct-tape all those into the system.[/color]

Not only is it short-sighted, I would say it is quite arrogant to
believe you can anticipate every possible use of this script you're
going to impliement, and can safely hold back essential language
features.

[color=blue]
> Anyway, that's my little rant on inventing your own scripting[/color]
language.[color=blue]
> Imbed[/color]

EMBED.

This spelling error wouldn't bother me if I didn't work with people
whose own job title is embedded control engineer, yet who still
misspell it "imbedded."

[color=blue]
> Python, or Perl, or TCL, or Ruby, or PHP,[/color]

Not PHP. PHP is one of the better (meaning less terrible) examples of
what happens when you do this sort of thing, which is not saying a lot.
PHP was originally not much more than a template engine with some
crude operations and decision-making ability. Only its restricted
problem domain has saved it from the junkheap where it belongs.

TCL isn't that great in this regard, either, as it makes a lot of
common operations that ought to be very simple terribly unweildy.

[color=blue]
> or Java, or whatever
> floats your boat. Almost any choice has got to be better than[/color]
rolling[color=blue]
> your own. Invest your intellectual capital doing what you can do[/color]
best,[color=blue]
> and don't get bogged down developing a new language.[/color]

You're right. I use a custom, domain-specific language in my work.
Whenever I use it, all I can think of is how much better this POS would
be if they had just extended Python (probably would even be faster).
At least they were smart enough to (try to) make it into a complete
programming language.


--
CARL BANKS

[Bengt Richter]

Re: Another scripting language implemented into Python itself?

On 24 Jan 2005 19:46:43 -0800, "Carl Banks" <invalidemail@a erojockey.com> wrote:
[...][color=blue][color=green]
>> Imbed[/color]
>
>EMBED.
>
>This spelling error wouldn't bother me if I didn't work with people
>whose own job title is embedded control engineer, yet who still
>misspell it "imbedded."
>[/color]
wordnet seems to accept it as an alternative spelling (not too recent):

[20:44] C:\pywk\sovm>wn imbed -over

Overview of verb imbed

The verb imbed has 1 sense (first 1 from tagged texts)

1. implant, engraft, embed, imbed, plant -- (to fix or set securely or deeply: "Kneeling, Cobb p
lanted a sturdy knee in the small of his back,")

funny that googling define:imbed gets nothing. Nor define:embed ??
I've had a number of misses in that kind of search. I wonder if it's
temporarily broken (or maybe it hit a licensing snag with the various
online dictionaries?)

Regards,
Bengt Richter

[Orlando Vazquez]

Re: Another scripting language implemented into Python itself?

Jeff Shannon wrote:

snip
[color=blue]
> Because you cannot make Python secure against a malicious (or ignorant)
> user -- there's too much flexibility to be able to guard against every
> possible way in which user-code could harm the system. Parsing your own
> (limited) scripting language allows much better control over what
> user-code is capable of doing, and therefore allows (at least some
> measure of) security against malicious code.[/color]

I don't see how that would equate to something that the original
programmer should be concerned about. You could include a bit in your
licensing scheme that voids all support on code that has been modified
in any way. You shouldn't be obligated and no one expects you to support
something the end-user has mucked with.

You could trivially enforce this by keeping checksums of all the system
files.

In any case, there's nothing you can really do to "secure" your code.
This is true of any language, C, C++, and especially scripting languages
like Python. Anyone who has the determination get at and modify the code
probably will.

The only time where I can see someone using another language in place of
Python for a scripting language is just domain-specific factors, e.g. if
you need the extension language to be easily used non-programmers.

Just a thought.

--
Orlando Vazquez

[Ola Natvig]

Re: Another scripting language implemented into Python itself?

Roy Smith wrote:[color=blue]
> In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
> Quest Master <zainalam@gmail .com> wrote:
>
>[color=green]
>>I am interested in developing an application where the user has an
>>ample amount of power to customize the application to their needs, and
>>I feel this would best be accomplished if a scripting language was
>>available. However, I want to code this application in Python, and I
>>have not yet heard of an implementation of another scripting language
>>into Python.
>>
>>An example of what I mean is this (an implementation of Lua into Ruby
>>-- which I'd prefer not to use): http://ruby-lua.unolotiene.com/
>>
>>I know C/C++ might be better suited for a task of this kind, but most
>>of the modules in my application which need speed have already been
>>coded in C++. I want to use Python as the "glue" for this project;
>>writing an entire application with a pretty GUI is not fun, as most of
>>you may know from previous experience.
>>
>>So, my question is simply this: is there an implementation of another
>>scripting language into Python?[/color]
>
>
> Python *is* a scripting language. Why not just let your users write
> Python modules which you them import and execute via some defined API?[/color]

There are examples of XML used for application configuration and in
template systems, I don't know how much power you intend to give your
users, but if it boils down to simple display logic and some small
'macro' calls to a predefined API, you could make some kind of tagged
language for that implementing basic flowcontroll functionality,
allowing function calling and definition.

You could look at wxWidgets/wxPython's XRC format, which are a XML
tagged format that are used to customize layout of wx forms.

But I don't think there are a implemented any fully usable scripting
languages like that in Python. But it should not be to much work if you
don't need many functions.

--
--------------------------------------
Ola Natvig <ola.natvig@inf osense.no>
infoSense AS / development

[Fuzzyman]

Re: Another scripting language implemented into Python itself?

An implementation of the core language semantics - without any modules
or file operations would be dead useful.

It could replace some of the function of the long dead rexec modules as
well as support projects like this.
Regards,


Fuzzy

http://www.voidspace.org.uk/python/index.shtml

[Arthur]

Re: Another scripting language implemented into Python itself?

On Mon, 24 Jan 2005 19:40:31 -0500, Roy Smith <roy@panix.co m> wrote:
[color=blue]
>In article <mailman.1231.1 106610969.22381 .python-list@python.org >,
> Quest Master <zainalam@gmail .com> wrote:
>
>
>Python *is* a scripting language. Why not just let your users write
>Python modules which you them import and execute via some defined API?[/color]

This is the tact I take with PyGeo.

The burden is on myself, as the API designer and documenter to make it
as accessible as I might want it to be. And I think I can accomplish
that without building in crippling limitations as to what depth a
"scripter" might want to explore - even to the extent of extending the
API itself.

I guess its a matter of the audience one hopes to reach. There are a
number of other dynamic geometry applications out there. Despite my
own interest in the subject, it was precisely the limitations their
API, whether GUI based or otherwise, that led me to the explorations
that is becoming PyGeo. It was the limitaions in exploring *geometry*
to which I refer. Having no per se interest in programming, I would
not impose the assumption of such an interest on my users.

I guess I hope to reach others like myself. With no particular
interest in programming, per se. Just with what you can get do with
it.

Art

[Roy Smith]

Re: Another scripting language implemented into Python itself?

"Carl Banks" <invalidemail@a erojockey.com> wrote:
[color=blue][color=green]
> > Imbed[/color]
> EMBED.[/color]

My apologies for being sloppy. And with an initial capital, so it just
jumps off the page at you :-)
[color=blue][color=green]
> > Python, or Perl, or TCL, or Ruby, or PHP,[/color]
>
> Not PHP. PHP is one of the better (meaning less terrible) examples of
> what happens when you do this sort of thing, which is not saying a lot.[/color]

But, that's exactly my point. To be honest, I've never used PHP. But
however bad it may be, at least it's got a few years of people fixing
bugs, writing books, writing add-on tools, etc, behind it. Better to
use somebody else's well-known and well-supported mess of a scripting
language than to invest several person-years inventing your own mess
that's no better.

There are a lot of existing scripting languages to pick from. It's nice
to pick the best one, but even if you pick the worst, that's probably
better than you can do on your own.
[color=blue]
> TCL isn't that great in this regard, either, as it makes a lot of
> common operations that ought to be very simple terribly unweildy.[/color]

In my last job, I did a lot of TCL. I've posted on this before (when I
was at a previous employer), so I'll just provide a pointer
(http://tinyurl.com/44w6n). That article says most of what that needs
saying, *AND* proves that I really do know how to spell embed :-)

It might be worth adding, however, that the TCL implementation discussed
above was a 3rd generation for that product. Generation #1 was a bunch
of shell scripts. Generation #2 was a home-grown scripting language.
Fortunately, they learned their lesson soon enough to rescue the project
with a conversion to TCL. I'm not sure how many person-years were
wasted both in the initial implementation and in the conversion effort,
but I imagine it was a $500,000 mistake.