I have a long text to expose to the user in a console, for him to make his choice. And I still haven't found how to reproduce the less/more effect with Python.
I'd be grateful for some directions on the proper way to achieve that. After a lot of googling I just understood that I don't know the tools or the appropriate vocabulary to get my way around this.
less and more mainly use terminal capabilities.
The main problem with these program is that most of them are made in c using termios.h/curses.h, so no great documentation about terminal capabilities exist in python but a good start should be the python termios doc and the gnu C library reference.
After a quick lookup the curses wrapper in python should also be able to do the job.
Related
I have a Python code that needs to be able to execute a C++ code. I'm new to the idea of creating libraries but from what I have learned so far I need to know whether I need to use static or dynamic linking.
I have read up on the pros and cons of both but there is a lot of jargon thrown around that I do not understand yet and since I need to do this ASAP I was wondering if some light can be shed on this from somebody who can explain it simply to me.
So here's the situation. My C++ code generates some text files that have data. My Python code then uses those text files to plot the data. As a starter, I need to be able to run the C++ code directly from Python. Is DLL more suitable than SL? Or am I barking up the completely wrong tree?
Extra: is it possible to edit variables in my C++ code, compile it and execute it, all directly from Python?
It depends on your desired deployment. If you use dynamic linking will need to carefully manage the libraries (.so, .dll) on your path and ensure that the correct version is loaded. This can be helped if you include the version number in the filename, but then that has its own problems (security... displaying version numbers of your code is a bad idea).
Another benefit is that you can swap your library functionality without a re-compile as long as the interface does not change.
Statically linking is conceptually simpler and practically simpler. You only have to deploy one artefact (an .exe for example). I recommend you start with that until you need to move to the more complicated shared library setup.
Edit: I don't understand your "extra credit" question. What do you mean by "edit values"? If you mean can you modify variables that were declared in your C++ code, then yes you can as long as you use part of the public interface to do it.
BTW this advice is for the general decision. If you are linking from Python to C/C++ I think you need to use a shared library. Not sure as I haven't done it myself.
EDIT: To expand on "public interface". When you create a C++ library of whatever kind, you specify what functions are available to outside classes (look up how to to that). This is what I mean by public interface. Parts of your library are inaccessible but others (that you specify) are able to be called from client code (i.e. your python script). This allows you to modify the values that are stored in memory.
If you DO mean that you want to edit the actual C++ code from within your python I would suggest that you should re-design your application. You should be able to customise the run-time behaviour of your C++ library by providing the appropriate configuration.
If you give a solid example of what you mean by that we'll be able to give you better advice.
Yes it is possible!!
Try exploring subprocess module in python.
Following can be an example implementation of your scenario:
yourfile.cpp
#compilation
args = ['g++','-o','your_executable_name_with_path','yourfile.cpp_with_path']
your_compile = subprocess.Popen(args,stdin=subprocess.PIPE,stderr=subprocess.PIPE,stdout=subprocess.PIPE)
output,compilation_error = your_compile.communicate()
your_compile.wait()
#successful compilation then there will be execuatble
if not compilation_error:
#execuation
args = ['your_executable_name_with_path'] #command to run a an execuatble
your_run = subprocess.Popen(args,stdin=subprocess.PIPE,stderr=subprocess.PIPE,stdout=subprocess.PIPE)
your_code_output,runtime_error = your_run.communicate()
your_run.wait()
Further, you can tackle more cases and come up with an efficient design
I'm not quite sure how the idea of linking comes into what you are asking, but it sounds to me like you want to use something like SWIG, which allows you to create wrappers around C++ functions (and many other languages) which you can then call directly from your Python code.
Extra: is it possible to edit values in my C++ code, compile it and execute it directly from Python?
If I'm understanding this correctly, you want to use Python to change your C++ code, then compile and execute it? If this is the case, you may want to look into embedding the Python interpreter in your C++ program. This would mean doing things the other way around and having C++ run your Python script, instead of trying to do everything from Python.
I've got an iOS app that needs to run efficiently and accurately. There's a lot of parameters involved in the code and different combinations of them provide varying results of success. So I plan to write a genetic algorithm to go ahead and find some good parameter sets for me. While I could do this using Objective-C directly in Xcode, I would complete this task much faster and enjoy it more writing the genetic algorithm part in Python. Is there any good way to control Xcode through Python? As in, be able to execute the simulator/device app through Xcode and get feedback from it using external code? I know a keyboard macro would be possible, but that approach would probably be a bit clumsy. If there's some way to directly control it programmatically, that would be great. Thanks!
Your question is not very clear.
Do you want to control Xcode to run your app ? Do you want to be able to change anything like flags automatically ?
If you want to control Xcode by writing code explaining what to do or even where to clic you can write an AppleScript
Maybe also take a look at this post
But if your question is about performing automatic UI tests maybe see UIAutomation, Calabash or MonkeyTalk
I've looked at most of the IDE's out there. I've set up vim to use autocompletion and I'm using it right now. However, I can't seem to get it to work like Visual Studio with .NET. Autocompletion seems to work only in certain cases and it only shows methods and not what parameters they take. It's pretty much unusable to me.
What I'm after is a pop-up that will show me all methods available and the parameters they take. Pretty much the feel of VS2010 when you're programming .NET.
You won't get the kind of autocompletion in a dynamic language like Python that you get in more explicitly typed languages. Consider:
def MyFunction(MyArg):
MyArg.
When you type the "." in MyArg., you expect the editor to provide a list of methods with arguments. That can't happen in Python because the editor has absolutely no way of knowing what type (or types) MyArg could possibly be. Even the Python compiler doesn't have that information when it's compiling the code. That's why, if you put MyArg.SomeNonExistentFunction() you won't get any kind of error message until runtime.
If you wrote something like:
def MyFunction:
MyObject = MyClass(SomeArg)
MyObject.
then a smart enough editor can supply a list of methods available after that final ".".
You'll find that those editors that are supplying autocomplete "sometimes" are doing so in cases similar to my second example, and not doing so in cases similar to the first. With Python, that's as good as you can get.
I've been using Eclipse with the PyDev extension for some time now. The auto-completion there is really quite impressive, I highly recommend it.
Gedit has a developer plugin which tries to do some syntax completion. For reasons already mentioned, it doesn't work very well. I found it more annoying than helpful and disabled it after a few weeks trial.
ipython's new Qt console has tab completion and you can have some tooltip sort of popups with syntax help and docstrings. See screenshot below for example..
But as most people have already pointed out, this kind of thing you are asking for is really more appropriate for less dynamic languages.
I am trying to develop a chrome extension in which i have coded all my
logic in 'python' . Now on browser action i want to pass parameters
and execute that .py file and return results to popup which will open
on browser action. To call a .py file from JavaScript i know i will
need to code a NPAPI plugin. But am confused between which approach i
should take. I have come across few options and am trying to choose
the easiest way to do it ..
Pyjamas Python Javascript Compiler : is a Python-to-Javascript
compiler which works as a language translator but on FAQ's of there
site last question suggest it will not run on Chrome. ( http://pyjs.org/)
FireBreath : FireBreath is a framework that allows easy creation of
powerful browser plugins. ( http://www.firebreath.org )
pyplugin - Python NPAPI plugin for XULRunner : It allows you to
build cross-platform graphical user interfaces using XUL and Python.
( http://pyplugin.com )
Plz Guide me to easiest way which will allow me to pass parameters and
execute that .py file and receive returned results from .py.
Thanx
Well, Pyjamas Python Javascript Compiler will not be complete -- not all python features are available in javascript, so it's impossible to convert all python to javascript. This may or may not do what you want, but I don't think it happens "on the fly", I think you have to write things on the desktop and run it through the "compiler" to get javascript out the other side.
FireBreath is the most awesomely amazing thing to ever hit the Internet -- I should know since I wrote it -- and it will absolutely allow you to do what you want, but you'll have to know how to tie into Python with C++ in order to do what you want. That said, you could probably use boost.python, which is included in the subset of boost that comes with FireBreath, but I've never used it so I don't know. You can pretty much do anything you want with an NPAPI plugin but you'll want to be real careful of security concerns.
A quick glance at pyplugin makes it look like pyplugin is basically what you'd be writing in FireBreath, but just a raw npapi plugin. If this will do what you want, it's probably the easiest way to go. It's designed to be used with XUL, which may be a problem since Chrome doesn't support XUL. You might also be able to modify it (since it's GPL) to do what you want. Of course, if you weren't planning to release your source, that could also be a problem.
The quickest way to solve your problem? Well, you'll have to decide; it'll take some more research, but I hope this is enough to at least get you started. Good luck!
I am trying to learn Python and referencing the documentation for the standard Python library from the Python website, and I was wondering if this was really the only library and documentation I will need or is there more? I do not plan to program advanced 3d graphics or anything advanced at the moment.
Edit:
Thanks very much for the responses, they were very useful. My problem is where to start on a script I have been thinking of. I want to write a script that converts images into a web format but I am not completely sure where to begin. Thanks for any more help you can provide.
For the basics, yes, the standard Python library is probably all you'll need. But as you continue programming in Python, eventually you will need some other library for some task -- for instance, I recently needed to generate a tone at a specific, but differing, frequency for an application, and pyAudiere did the job just right.
A lot of the other libraries out there generate their documentation differently from the core Python style -- it's just visually different, the content is the same. Some only have docstrings, and you'll be best off reading them in a console, perhaps.
Regardless of how the other documentation is generated, get used to looking through the Python APIs to find the functions/classes/methods you need. When the time comes for you to use non-core libraries, you'll know what you want to do, but you'll have to find how to do it.
For the future, it wouldn't hurt to be familiar with C, either. There's a number of Python libraries that are actually just wrappers around C libraries, and the documentation for the Python libraries is just the same as the documentation for the C libraries. PyOpenGL comes to mind, but it's been a while since I've personally used it.
As others have said, it depends on what you're into. The package index at http://pypi.python.org/pypi/ has categories and summaries that are helpful in seeing what other libraries are available for different purposes. (Select "Browse packages" on the left to see the categories.)
One very common library, that should also fit your current needs, is the Python Image Library (PIL).
Note: the latest version is still in beta, and available only at Effbot site.
If you're just beginning, all you'll need to know is the stuff you can get from the Python website. Failing that a quick Google is the fastest way to get (most) Python answers these days.
As you develop your skills and become more advanced, you'll start looking for more exciting things to do, at which point you'll naturally start coming across other libraries (for example, pygame) that you can use for your more advanced projects.
It's very hard to answer this without knowing what you're planning on using Python for. I recommend Dive Into Python as a useful resource for learning Python.
In terms of popular third party frameworks, for web applications there's the Django framework and associated documentation, network stuff there's Twisted ... the list goes on. It really depends on what you're hoping to do!
Assuming that the standard library doesn't provide what we need and we don't have the time, or the knowledge, to implement the code we reuse 3rd party libraries.
This is a common attitude regardless of the programming language.
If there's a chance that someone else ever wanted to do what you want to do, there's a chance that someone created a library for it. A few minutes Googling something like "python image library" will find you what you need, or let you know that someone hasn't created a library for your purposes.