Re: find out whether a module exists (without importing it)
in my opinion, without importing it makes it unnecessarily complicated. You just want to know it module xyz exists, or better said can be found (sys.path). why not try - except[ - else ] try: import mymodule except ImportError: # NOW YOU KNOW it does not exist #+ and you may react properly ?? * Gelonida N gelon...@gmail.com [2012-08-06 22:49]: Is this possible. let's say I'd like to know whether I could import the module 'mypackage.mymodule', meaning, whther this module is located somewhere in sys.path i tried to use imp.find_module(), but it didn't find any module name containing a '.' Am I doing anything wrong? Is there another existing implementation, that helps. I could do this manually, but this is something I'd just like to do if necessary. -- http://mail.python.org/mailman/listinfo/python-list -- Michael Poeltl Computational Materials Physics voice: +43-1-4277-51409 Univ. Wien, Sensengasse 8/12 fax: +43-1-4277-9514 (or 9513) A-1090 Wien, AUSTRIA cmp.mpi.univie.ac.at --- ubuntu-11.10 | vim-7.3 | python-3.2.2 | mutt-1.5.21 | elinks-0.12 --- -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
Hi Michael, On 08/07/2012 08:43 AM, Michael Poeltl wrote: in my opinion, without importing it makes it unnecessarily complicated. It does, but I think this is what I want, thus my question. I tried to keep my question simple without explaining too much. Well now here's a little more context. There's two reasons why I sepcified the without importing it. Some modules may have side effects when being imported,and sometimes I just want to check for a module's existence Second: Sometimes I only want to know, whether a module exists. I do not want to know whether a module is syntactically correct or whether a module if imported is capable of importing all it's submodules What I'd like to achieve at the moment is to distinguish three situations: - a module with a given name does not exist - a module with a given name exists and produces errors (might be ImportErors) - a module with a given name exists and can be imported In fact what I really want to achieve is: import a module if it exists (and fail if it is broken) if it doesn't exist import a 'default' module and go on. The name of the module is stored in a variable and is not known prior to running the script so the code, that you suggested would be something like. modulename = 'my.module' cmd = 'import %s as amodule' try: exec(cmd) print imported successfully except ImportError: print module doesn't exist or the module tries to \ import another module that doesn't exist # if the module doesn't exist I'd like to import a 'fallback' module # otherwise I'd like to abort. except Exception as exc: print module exists, but is broken raise exc amodule.do_something() You just want to know it module xyz exists, or better said can be found (sys.path). why not try - except[ - else ] try: import mymodule except ImportError: # NOW YOU KNOW it does not exist #+ and you may react properly ?? * Gelonida N gelon...@gmail.com [2012-08-06 22:49]: Is this possible. let's say I'd like to know whether I could import the module 'mypackage.mymodule', meaning, whther this module is located somewhere in sys.path i tried to use imp.find_module(), but it didn't find any module name containing a '.' Am I doing anything wrong? Is there another existing implementation, that helps. I could do this manually, but this is something I'd just like to do if necessary. -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
Gelonida N wrote: Is this possible. let's say I'd like to know whether I could import the module 'mypackage.mymodule', meaning, whther this module is located somewhere in sys.path i tried to use imp.find_module(), but it didn't find any module name containing a '.' You could look for the toplevel name and then look for modules in the corresponding directory. This is not always reliable as a package may not correspond to a directory (e. g.: os and os.path), but I don't think you can get any closer without performing an actual import. -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
On Tue, Aug 7, 2012 at 6:00 PM, Gelonida N gelon...@gmail.com wrote: modulename = 'my.module' cmd = 'import %s as amodule' try: exec(cmd) print imported successfully Someone will doubtless correct me if I'm wrong, but I think you can avoid exec here with: amodule=__import__(modulename) ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
You are correct. On 7 August 2012 14:38, Chris Angelico ros...@gmail.com wrote: On Tue, Aug 7, 2012 at 6:00 PM, Gelonida N gelon...@gmail.com wrote: modulename = 'my.module' cmd = 'import %s as amodule' try: exec(cmd) print imported successfully Someone will doubtless correct me if I'm wrong, but I think you can avoid exec here with: amodule=__import__(modulename) ChrisA -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
imp.find_module(), but it didn't find any module name containing a '.' The docs (http://docs.python.org/library/imp.html#imp.find_module) clearly say: This function does not handle hierarchical module names (names containing dots). In order to find P.M, that is, submodule M of package P, use find_module() and load_module() to find and load package P, and then use find_module() with the path argument set to P.__path__. When P itself has a dotted name, apply this recipe recursively. See https://gist.github.com/3278829 for possible implementation. -- http://mail.python.org/mailman/listinfo/python-list
Re: find out whether a module exists (without importing it)
On 08/06/2012 11:58 PM, Miki Tebeka wrote: imp.find_module(), but it didn't find any module name containing a '.' The docs (http://docs.python.org/library/imp.html#imp.find_module) clearly say: This function does not handle hierarchical module names(names containing dots). Thanks, Well this explains. In order to find P.M, that is, submodule M of package P, use find_module() and load_module() to find and load package P, and then use find_module() with the path argument set to P.__path__. When P itself has a dotted name, apply this recipe recursively. See https://gist.github.com/3278829 for possible implementation. Using imp and then iterating (as you suggested) is probably the fastest solution. This is what I will do. Thanks again. -- http://mail.python.org/mailman/listinfo/python-list
