Two questions

Discussion in 'Python' started by qscomputing@gmail.com, Jun 2, 2005.

  1. Guest

    Hi,

    I've developed in several other languages and have recently found
    Python and I'm trying to use it in the shape of the PythonCard
    application development tool.

    My two questions:

    1. What is the easiest way to create a for loop in the style I'm used
    to from Delphi ie:
    for I:=0 to 2 do begin
    //code
    end;

    2. Philospohy(sp?) aside, I could potentially want to create a
    binary-only distribution of my finished apps. I noticed the
    documentation on .pyc files: how do I create these and, aside from
    being basically read-only, are they used just like ordinary .py source
    files? And can they be easily reverse-engineered?

    Thanks,
    - QS Computing.
    , Jun 2, 2005
    #1
    1. Advertising

  2. On 2 Jun 2005 06:45:18 -0700, said:
    > Hi,
    >
    > I've developed in several other languages and have recently found
    > Python and I'm trying to use it in the shape of the PythonCard
    > application development tool.
    >
    > My two questions:
    >
    > 1. What is the easiest way to create a for loop in the style I'm used
    > to from Delphi ie:
    > for I:=0 to 2 do begin
    > //code
    > end;
    >

    for i in range(0, 2):
    do stuff

    The range([start], stop, [step]) function generates a sequence of
    numbers which the the for loop iterates over.

    (You can also use xrange() for a more memory efficient solution for very
    large ranges).

    > 2. Philospohy(sp?) aside, I could potentially want to create a
    > binary-only distribution of my finished apps. I noticed the
    > documentation on .pyc files: how do I create these and, aside from
    > being basically read-only, are they used just like ordinary .py source
    > files? And can they be easily reverse-engineered?
    >

    To create binary only distributions for Windows you can use py2exe. Its
    distributions files can be fairly easily reverse engineered.

    Cheers,
    Richard
    Richard Lewis, Jun 2, 2005
    #2
    1. Advertising

  3. Peter Hansen Guest

    wrote:
    > I've developed in several other languages and have recently found
    > Python and I'm trying to use it in the shape of the PythonCard
    > application development tool.
    >
    > My two questions:
    >
    > 1. What is the easiest way to create a for loop in the style I'm used
    > to from Delphi ie:
    > for I:=0 to 2 do begin
    > //code
    > end;


    for i in xrange(0, 3):
    # code

    Please read the tutorial. I'm fairly sure this and many more things
    you'll want to know are covered adequately.

    > 2. Philospohy(sp?) aside, I could potentially want to create a
    > binary-only distribution of my finished apps. I noticed the
    > documentation on .pyc files: how do I create these and, aside from
    > being basically read-only, are they used just like ordinary .py source
    > files? And can they be easily reverse-engineered?


    They are compiled versions of the .py files, so definitely not the same.
    They are created automatically and transparently when you import .py
    modules, so normally you don't pay any attention to them. They can
    easily be reverse-engineered, if by that you mean turned back into
    source code. See "decompyle" for example. Using the "compileall"
    module you can manually compile .py to .pyc but, again, that's generally
    not needed. Use of tools like py2exe is generally advised for packaging
    and distibution if you don't want to distribute source, though few of
    the existing tools do much more than package up .pyc files inside
    archives, bundle the runtime library, and add wrapper code to make the
    execution transparent.

    Philosophy not entirely aside, you should note that object code in any
    language can "easily" be reverse-engineered in the same way, with the
    only difference being the degree of ease involved. If the code is worth
    enough to someone that they are willing to risk violating your license
    terms, they *will* be able to recover enough source code (whether it was
    Python, C, or assembly) to do what they need. The only certain
    protection is to keep the valuable code on a server and use some kind of
    web service (or whatever) to control access to its execution. (There
    have been *many* past discussions of all this in the forum -- it's a
    very tired topic by now -- so please feel free to peruse the archives
    via Google Groups before asking lots of the same questions over again.
    You'll be doing yourself a favour.)

    -Peter
    Peter Hansen, Jun 2, 2005
    #3
  4. Joal Heagney Guest

    wrote:
    > Hi,
    >
    > I've developed in several other languages and have recently found
    > Python and I'm trying to use it in the shape of the PythonCard
    > application development tool.
    >
    > My two questions:
    >
    > 1. What is the easiest way to create a for loop in the style I'm used
    > to from Delphi ie:
    > for I:=0 to 2 do begin
    > //code
    > end;


    Um, assuming that this loops through the numbers 0 to 2 and assigns them
    to the variable I, and then does something in code with I after it's
    been assigned, the python equivalent is:

    for I in range(0,3):
    //code

    (Note the whitespace after opening the for loop?)
    And then break the indenting to finish the for loop. So you're next
    piece of code (Whatever you had after end;) would go here:

    //morecode.

    > 2. Philospohy(sp?) aside, I could potentially want to create a
    > binary-only distribution of my finished apps. I noticed the
    > documentation on .pyc files: how do I create these and, aside from
    > being basically read-only, are they used just like ordinary .py source
    > files? And can they be easily reverse-engineered?


    As long as you have write access to the directory that you're .py files
    are in, when you run python, it will generate the .pyc files for you as
    they are loaded.
    There is also a utility script in the main distribution called
    py_compile.py.
    E.g. compiling a whole directory of .py files:

    python /path/to/main/install/py_compile.py *.py

    And to compile them as optimised binary files (.pyo):
    python -O /path/to/main/install/py_compile.py *.py

    They are used like ordinary .py source files. (Python actually executes
    from the .pyc files it builds from your .py files.)
    They can be reverse-engineered, but then so can Java/C++/Assembler. Have
    a look through the group for something about being able to distribute
    your modules.pyc as a zipfile - I remember something about being able to
    do a -tiny- bit of extra protection by having them as a passworded zip file.

    > Thanks,
    > - QS Computing.
    >


    Welcome.

    Joal
    Joal Heagney, Jun 2, 2005
    #4
  5. rbt Guest

    Peter Hansen wrote:
    > Philosophy not entirely aside, you should note that object code in any
    > language can "easily" be reverse-engineered in the same way, with the
    > only difference being the degree of ease involved. If the code is worth
    > enough to someone that they are willing to risk violating your license
    > terms, they *will* be able to recover enough source code (whether it was
    > Python, C, or assembly) to do what they need.


    Don't intend to hijack this thread, but this bit interests me. I know
    several accomplished C/assembly programmers who have told me that
    reverse engineering object code from either of these two languages is
    anything but trivial. Yet, I *hear* and *read* the opposite all of the
    time. Can anyone actually demonstrate a decompile that mirrors the
    original source?

    Also, I'd venture to say that the number of people in the world who can
    consistently reverse engineer object code is almost statistically
    insignificant... sure, they are out there, but you'll win the lottery
    before you meet one of them and most of them work for big, bad
    government agencies ;)
    rbt, Jun 2, 2005
    #5
  6. rbt wrote:
    > Peter Hansen wrote:
    >
    >> Philosophy not entirely aside, you should note that object code in any
    >> language can "easily" be reverse-engineered in the same way, with the
    >> only difference being the degree of ease involved. If the code is
    >> worth enough to someone that they are willing to risk violating your
    >> license terms, they *will* be able to recover enough source code
    >> (whether it was Python, C, or assembly) to do what they need.

    >
    >
    > Don't intend to hijack this thread, but this bit interests me. I know
    > several accomplished C/assembly programmers who have told me that
    > reverse engineering object code from either of these two languages is
    > anything but trivial. Yet, I *hear* and *read* the opposite all of the
    > time. Can anyone actually demonstrate a decompile that mirrors the
    > original source?


    I give you one example: Online/Multiplayer GTA 3 or 4
    (http://gta3mta.tk/)

    A C-App never intended to work that way - but skillfully patched so that
    it works! And that even only as OSS - no commercial interest (and thus
    funding). So I day Peter's statement has full validity - it's a question
    of interest.

    Diez
    Diez B. Roggisch, Jun 2, 2005
    #6
  7. Richard Lewis wrote:
    > On 2 Jun 2005 06:45:18 -0700, said:
    >> Hi,
    >>
    >> I've developed in several other languages and have recently found
    >> Python and I'm trying to use it in the shape of the PythonCard
    >> application development tool.
    >>
    >> My two questions:
    >>
    >> 1. What is the easiest way to create a for loop in the style I'm used
    >> to from Delphi ie:
    >> for I:=0 to 2 do begin
    >> //code
    >> end;
    >>

    > for i in range(0, 2):
    > do stuff


    Eh, no. range(0, 3) would be correct, since the Python range function
    generates a list from start to stop-1.

    > The range([start], stop, [step]) function generates a sequence of
    > numbers which the the for loop iterates over.
    >
    > (You can also use xrange() for a more memory efficient solution for very
    > large ranges).
    >
    >> 2. Philospohy(sp?) aside, I could potentially want to create a
    >> binary-only distribution of my finished apps. I noticed the
    >> documentation on .pyc files: how do I create these and, aside from
    >> being basically read-only, are they used just like ordinary .py source
    >> files? And can they be easily reverse-engineered?


    They are a binary representation of bytecode, just like in Java. They can be
    reverse-engineered more easily than machine code, but it still is no no-brainer.
    Btw, they are created automatically...

    Reinhold
    Reinhold Birkenfeld, Jun 2, 2005
    #7
  8. Guest

    Thanks to you all for the quick response.

    I've noticed that when I do
    $ python myprog.py
    the file myprog.pyc file is not created, but the .pyc files for files I
    import *are* created. Is this intentional and, if so, how do I get the
    myprog.pyc file?

    Thanks,
    - QS Computing.
    , Jun 2, 2005
    #8
  9. Peter Hansen Guest

    wrote:
    > Thanks to you all for the quick response.
    >
    > I've noticed that when I do
    > $ python myprog.py
    > the file myprog.pyc file is not created, but the .pyc files for files I
    > import *are* created. Is this intentional and, if so, how do I get the
    > myprog.pyc file?


    I thought the docs covered this, so I left it out. The
    "main" .py file is not converted to a .pyc file for reasons I can't
    remember (and don't care... after it, that's just the way it is). If
    you really need a .pyc for it, the simplest thing to do is "import
    myprog" from the interactive prompt. The compileall module I mentioned
    would also be able to do this.

    -Peter
    Peter Hansen, Jun 2, 2005
    #9
  10. Peter Hansen Guest

    rbt wrote:
    > Peter Hansen wrote:
    >> Philosophy not entirely aside, you should note that object code in any
    >> language can "easily" be reverse-engineered in the same way, with the
    >> only difference being the degree of ease involved. If the code is
    >> worth enough to someone that they are willing to risk violating your
    >> license terms, they *will* be able to recover enough source code
    >> (whether it was Python, C, or assembly) to do what they need.

    >
    > Don't intend to hijack this thread, but this bit interests me. I know
    > several accomplished C/assembly programmers who have told me that
    > reverse engineering object code from either of these two languages is
    > anything but trivial. Yet, I *hear* and *read* the opposite all of the
    > time. Can anyone actually demonstrate a decompile that mirrors the
    > original source?


    It all depends on the definition of "reverse engineering".

    In my opinion and experience, very little code in the world is so
    sophisticated that it is not roughly as easy to write equivalent code
    from scratch (with the original, working program as a guide of what the
    code actually does) as it would be to convert the object code back into
    source. (Exceptions such as "decompyle" which may make the job near
    trivial aside.)

    If that's true, it leaves us with a very small subset of the code in any
    given program, that might actually be worth the effort of converting
    back to source. That bit of code will generally turn out to be so small
    that once again an automated conversion to source is not really
    necessary, since analysis of the object code would with relatively
    little effort allow one to "reverse engineer" some equivalent source, in
    whatever language (or pseudo-code) one chose.

    So, for languages like C, where the compilation process is fairly
    "destructive" to things like the variable names and control structures
    used, "reverse engineering" in the sense of "automated conversion back
    to equivalent source code" is rather difficult, probably infeasibly so
    for most non-trivial programs. I personally don't understand the need
    for this, other than in the case of "I lost my source", and the correct
    answer there is a session of pummelling, followed by tarring and
    feathering with the pages of the Subversion Book.

    On the other hand, "reverse engineering" in the sense of "creating
    source code capable of reproducing the effects of the valuable and
    interesting parts of the object code" is not that difficult, and in the
    sense of "understanding how this code works" is even easier, being just
    the first part of that step.

    Software development is far more about choosing the right problems to
    solve and the right ways to solve them than it is about writing source
    code for the program that will do the job.

    And if I had an automated tool to reproduce source code for a given
    program, I'd still be very concerned that I didn't end up with any of
    its automated test cases. ;-)

    -Peter
    Peter Hansen, Jun 2, 2005
    #10
  11. On Thu, 02 Jun 2005 06:45:18 -0700, qscomputing wrote:

    > Hi,
    >
    > I've developed in several other languages and have recently found
    > Python and I'm trying to use it in the shape of the PythonCard
    > application development tool.
    >
    > My two questions:
    >
    > 1. What is the easiest way to create a for loop in the style I'm used
    > to from Delphi ie:
    > for I:=0 to 2 do begin
    > //code
    > end;


    Use Delphi.

    If you insist on using Python (and why wouldn't you?), then I'm afraid
    you will have to create for loops in the Python style:

    for i in range(3):
    do_something


    Notice the small gotcha: if you want to loop over the values 0, 1, and 2,
    you have to use range(3), NOT range(2). This may seem strange now, but it
    is actually very useful and prevents a lot of off-by-one errors.



    > 2. Philospohy(sp?) aside,


    Philosophy.

    > I could potentially want to create a
    > binary-only distribution of my finished apps. I noticed the
    > documentation on .pyc files: how do I create these


    In PythonCard? I have no idea. Sorry.

    In ordinary Python?

    When you run or import a Python module, the Python interpreter first looks
    for a .pyc file of the same name that is more recent than the .py file. If
    it doesn't find one, it compiles the .py file into byte-code, stores the
    byte-code in the .pyc file, and runs that.

    In other words, to create your .pyc file, just run your .py file and
    Python will do it automatically.

    > and, aside from
    > being basically read-only, are they used just like ordinary .py source
    > files? And can they be easily reverse-engineered?


    Yes, they can be easily reverse-engineered.

    The short answer is, Python has not been designed to hide your code. If
    that's what you are trying to do, perhaps you need to think about _why_
    you want to go to all that extra effort to keep your software secret,
    rather than just _how_ to keep it secret.

    I can think of a number of reasons why somebody might want to hide their
    code. In no particular order:

    (1) You are ashamed of the quality of your buggy code, and don't want
    people to see how bad it is. If so, learn to write better code, and the
    best way of doing that is to let people see your code and give you advice.

    (2) You have stolen somebody else's code, and are trying to keep that fact
    secret. If so, pay the licence fee, or legally reverse-engineer the code,
    or use OpenSource software that allows copying. If the code you have
    stolen is valuable enough, the legal owners will find out, even without
    the source code.

    (3) You have create an incredibly valuable piece of code that will be
    worth millions, but only if nobody can see the source code. Yeah right.

    (4) "It's MY CODE, nobody is allowed to use it unless I SAY SO!!!" Fine,
    whatever you say, there are tens or hundreds of thousands of OpenSource
    software packages competing with your software without those restrictions.
    Good luck.

    (5) Your code has security holes and you hope that the bad guys won't find
    them without access to the source code. Be prepared for serious
    embarrassment, because the crackers WILL crack your code, source code or
    no source code. Obscurity is no substitute for security.

    (6) You are worried about people copying the code for their friends
    without paying you for it. How does keeping the source code secret stop
    them from copying the .pyc files and giving them to their friends?

    (7) You are using secret programs licenced from another programmer or
    company, and the conditions of use are that the source code isn't made
    available. Good luck, I hope it works out for you.

    (8) You are programming a game or puzzle, and you don't want players to
    cheat by reading the source code. Consider pulling out the information
    they need to cheat and putting it in an encrypted data file instead.

    There may be other reasons for wanting to keep the code secret. Some of
    them might even be good reasons, for some value of "good".

    The reality is, the more valuable your code is, the more effort people
    will put into reverse-engineering it. People will find out how it works,
    if they care enough, and the more valuable your program, the more they
    will care.

    On the other hand, there are incredible advantages to making your code
    available to the users of your software. I'm sure you already know those
    advantages: you are learning Python, which is based on those principles of
    openness.

    If you want to discuss these issues further, please feel free.

    If you really what to hide your code, you might like to think about using
    C-extensions instead.

    --
    Steven
    Steven D'Aprano, Jun 2, 2005
    #11
  12. Guest

    > > 1. What is the easiest way to create a for loop in the style I'm used
    > > to from Delphi

    >
    > Use Delphi.


    Very literal interpretation of my text: I should have said "in a
    similar style to". :)

    > I can think of a number of reasons why somebody might want to hide their
    > code.


    I can't really think of any pressing reasons for wanting to hide code
    other than a habit developed from coding in Windows where, as I'm sure
    you'll know, doing otherwise is considered a bit odd. Like all habits,
    it's a hard one to break. :-(
    , Jun 2, 2005
    #12
  13. John Machin Guest

    Peter Hansen wrote:
    > wrote:
    >
    >> Thanks to you all for the quick response.
    >>
    >> I've noticed that when I do
    >> $ python myprog.py
    >> the file myprog.pyc file is not created, but the .pyc files for files I
    >> import *are* created. Is this intentional and, if so, how do I get the
    >> myprog.pyc file?

    >
    >
    > I thought the docs covered this, so I left it out. The
    > "main" .py file is not converted to a .pyc file for reasons I can't
    > remember (and don't care... after it, that's just the way it is). If
    > you really need a .pyc for it, the simplest thing to do is "import
    > myprog" from the interactive prompt.


    *Provided* the "main" .py file has been set up properly, in the sense
    that the scripty bits are guarded by "if __name__ == '__main__':"

    Otherwise side effects (possibly horrid) may occur upon import.

    Another way around this is for myprog.py to be a stub which merely does
    something like this:

    if __name__ == "__main__":
    import myrealprog
    myrealprog.main()



    > The compileall module I mentioned
    > would also be able to do this.
    >
    > -Peter
    John Machin, Jun 2, 2005
    #13
  14. John Machin Guest

    Steven D'Aprano wrote:
    > On Thu, 02 Jun 2005 06:45:18 -0700, qscomputing wrote:
    >
    >>2. Philospohy(sp?) aside,

    >
    >
    > Philosophy.
    >
    >
    >>I could potentially want to create a
    >>binary-only distribution of my finished apps. I noticed the
    >>documentation on .pyc files: how do I create these

    >
    >
    > In PythonCard? I have no idea. Sorry.
    >
    > In ordinary Python?
    >
    > When you run or import a Python module, the Python interpreter first looks
    > for a .pyc file of the same name that is more recent than the .py file. If
    > it doesn't find one, it compiles the .py file into byte-code, stores the
    > byte-code in the .pyc file, and runs that.
    >
    > In other words, to create your .pyc file, just run your .py file and
    > Python will do it automatically.
    >


    The notion that just running a .py file will create a .pyc file is
    contrary to widely-held belief, and (admittedly small, but very recent,
    on Python 2.4.1, in a directory to which I have and had write access)
    empirical evidence. I can't be bothered checking *all* sightings of the
    time machine but my copy of 1.5.2 exhibits the same behaviour.

    Is it possible that you could be mistaken?
    John Machin, Jun 2, 2005
    #14
  15. Andrew Dalke Guest

    Steven D'Aprano wrote:
    > I can think of a number of reasons why somebody might want to hide their
    > code. In no particular order:


    > (3) You have create an incredibly valuable piece of code that will be
    > worth millions, but only if nobody can see the source code. Yeah right.


    - id software makes a lot of money licensing their 3D FPS engine

    - stock market trading companies make money in part by having
    specialized software to help with market trading, forecasts, etc.

    > (8) You are programming a game or puzzle, and you don't want players to
    > cheat by reading the source code. Consider pulling out the information
    > they need to cheat and putting it in an encrypted data file instead.


    But code is data ...


    > There may be other reasons for wanting to keep the code secret. Some of
    > them might even be good reasons, for some value of "good".


    You are the US government developing software to design/test the
    next generation nuclear weapons system and don't want any other
    country to use it. (GnuNuke?)

    You are a student working on a take-home example and you aren't
    allowed to work with/help anyone else


    > If you really what to hide your code, you might like to think about
    > using C-extensions instead.


    Or go the Amazon/EBay/Google approach and provide only client access
    to your code.

    Andrew
    Andrew Dalke, Jun 2, 2005
    #15
  16. John Machin wrote:

    >> In other words, to create your .pyc file, just run your .py file and
    >> Python will do it automatically.
    >>

    >
    > The notion that just running a .py file will create a .pyc file is
    > contrary to widely-held belief, and (admittedly small, but very recent,
    > on Python 2.4.1, in a directory to which I have and had write access)
    > empirical evidence. I can't be bothered checking *all* sightings of the
    > time machine but my copy of 1.5.2 exhibits the same behaviour.
    >
    > Is it possible that you could be mistaken?


    Well, its been known to happen before. Especially at 3am.

    So yes, it is certainly possible that I'm mistaken.
    However, I'm assured that in Python3000, the Python
    byte-code interpreter will be integrated with Guido's
    time machine so that the .pyc file will be created
    before you even write the .py file, thus saving a lot
    of development time.


    --
    Steven.
    Steven D'Aprano, Jun 3, 2005
    #16
  17. Greg Ewing Guest

    Andrew Dalke wrote:

    > You are the US government developing software to design/test the
    > next generation nuclear weapons system and don't want any other
    > country to use it. (GnuNuke?)


    Hmmm... if these are GPL weapons, if you want to fire
    them at anyone you'll *have* to make them available to
    all other countries as well... not good for
    non-proliferation...

    --
    Greg Ewing, Computer Science Dept,
    University of Canterbury,
    Christchurch, New Zealand
    http://www.cosc.canterbury.ac.nz/~greg
    Greg Ewing, Jun 3, 2005
    #17
  18. Andrew Dalke Guest

    Greg Ewing wrote:
    > Hmmm... if these are GPL weapons, if you want to fire
    > them at anyone you'll *have* to make them available to
    > all other countries as well... not good for
    > non-proliferation...


    I think the source code only needs to be sent to the
    country which receive the weapons. Include a DVD with
    the warhead (in a usable form for further development)
    and the GPL should be satisfied.

    Andrew
    Andrew Dalke, Jun 3, 2005
    #18
  19. alex23 Guest

    Sorry to continue with the thread hijack...

    Steven D'Aprano wrote:
    > (3) You have create an incredibly valuable piece of code that will be
    > worth millions, but only if nobody can see the source code. Yeah right.


    An interesting corollay that comes from source code transparency is
    that it generally makes it a lot easier to see who has stolen from you.

    -alex23
    alex23, Jun 3, 2005
    #19
  20. Andrew Dalke wrote:


    > Steven D'Aprano wrote:
    >
    >>I can think of a number of reasons why somebody might want to hide their
    >>code. In no particular order:

    >
    >
    >>(3) You have create an incredibly valuable piece of code that will be
    >>worth millions, but only if nobody can see the source code. Yeah right.

    >
    >
    > - id software makes a lot of money licensing their 3D FPS engine


    The existence of one or two or a thousand profitable
    software packages out of the millions in existence does
    not invalidate my skepticism that some random piece of
    software will directly make money for the developer.
    Even assuming that the money-making ability would be
    lost if the source code was available, which is not a
    given (id software open-sources old versions of their
    rendering engines, and MySQL is quite profitable and
    their software is available source code and all).

    Software rarely makes money for the developers
    directly. The odds are against any developer, hence my
    skepticism.

    > - stock market trading companies make money in part by having
    > specialized software to help with market trading, forecasts, etc.


    You are mixing up a number of seperate issues here.

    If the trading company keeps the software in-house,
    then the issue of making the source code available is
    irrelevent since they don't distribute the object code
    either.

    If they distribute the software externally, then they
    almost certainly have more protection from licence
    agreements and copyright than they get from merely
    hiding the source. If they even do hide the source
    code, which is not a given.

    As for the issue of them making money, I'm not
    suggesting that software can't make money for a
    business. I work for a business that makes money from
    Linux, Apache, perl, Python and other FOSS in the same
    way that a carpenter makes money from a hammer: they
    are tools that we use to provide products and services
    that we sell for profit.

    In-house use of market forecasting software falls into
    the "carpenter's hammer" category, not the "make money
    by selling software" category.

    As for selling forecasting software, well, you haven't
    demonstrated that making the source code available
    would harm the ability to make money from it. Firstly,
    very often the value of the software is not the
    algorithms they use (curve fitting software and
    extrapolation algorithms are hardly secret), but the
    data used by the algorithm. So long as you keep the
    financial data proprietary, keeping the source code
    secret adds nothing.

    Secondly, even if the software is rubbish, and the
    forecasts give results no better than chance, doesn't
    mean the company can't make money selling it. Look at
    the popularity of "systems" for predicting lottery numbers.

    >>(8) You are programming a game or puzzle, and you don't want players to
    >>cheat by reading the source code. Consider pulling out the information
    >>they need to cheat and putting it in an encrypted data file instead.

    >
    >
    > But code is data ...


    A pedantic point that doesn't add anything to the
    discussion :) Not all the data in a puzzle allows the
    player to cheat, does it? Case in point: knowing how
    Solitaire draws the cards on the screen doesn't help
    you win any games.

    >>There may be other reasons for wanting to keep the code secret. Some of
    >>them might even be good reasons, for some value of "good".

    >
    >
    > You are the US government developing software to design/test the
    > next generation nuclear weapons system and don't want any other
    > country to use it. (GnuNuke?)


    Then don't distribute the software, object or source code.


    > You are a student working on a take-home example and you aren't
    > allowed to work with/help anyone else


    Er, I don't see how this is supposed to work. An
    example of what? How does keeping the source code
    secret prevent the student from working with others?


    >>If you really what to hide your code, you might like to think about
    >>using C-extensions instead.

    >
    >
    > Or go the Amazon/EBay/Google approach and provide only client access
    > to your code.


    Yes, good point. That's another way of telling your
    customers under what circumstances they are allowed to
    use the software. And who knows, if your software is
    valuable enough and unique enough, they may even be
    prepared to work the way you want them to work instead
    of the way they want to work.


    --
    Steven.
    Steven D'Aprano, Jun 3, 2005
    #20
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