Module imports during object instantiation

[Ritesh Raj Sarraf]

On Aug 15, 11:42 pm, Neil Cerutti <horp... at yahoo.com> wrote:
> On 2007-08-15, Ritesh Raj Sarraf <r... at researchut.com> wrote:
> > Or am I terribly missing something that you are trying to tell ?
>
> I didn't see log = Log() in your example. Sorry for the
> excursion.
>
> Are you sure os.name is 'posix' on your system?
>


Here again for you:

In [6]: cat rick.py
IPython system call: cat rick.py
import os, sys

class Log:
    def __init__(self, verbose, lock = None):
        self.VERBOSE = bool(verbose)
        self.lock = bool(lock)

        if self.lock:
            self.dispLock = threading.Lock()
        else:
            self.dispLock = None

        if os.name == 'posix':
            try:
                import foobar
            except ImportError, e:
                print >> sys.stderr, e

            self.platform = 'posix'
            self.color = get_colors()

        elif os.name in ['nt', 'dos']:
            self.platform = 'microsoft'
            try:
                import SomeModule
            except ImportError, e:
                # comment out next line before going to prod...
                print >> sys.stderr, e

                self.color = None
            else:
                self.color = SomeModule.get_colors_windows()
        else:
            self.platform = None
            self.color = None

In [7]: from rick import Log

In [8]: log = Log(verbose = True)
No module named foobar
---------------------------------------------------------------------------
exceptions.NameError                                 Traceback (most
recent call last)

/tmp/<ipython console>

/tmp/rick.py in __init__(self, verbose, lock)
     18
     19             self.platform = 'posix'
---> 20             self.color = get_colors()
     21
     22         elif os.name in ['nt', 'dos']:

NameError: global name 'get_colors' is not defined

In [9]: os.name
Out[9]: 'posix'

In [10]: import foobar
---------------------------------------------------------------------------
exceptions.ImportError                               Traceback (most
recent call last)

/tmp/<ipython console>

ImportError: No module named foobar

In [11]:


Okay!! Ignore line 20 for now because that is not what this whole
thread has been about. In the code, just 2 lines above "self.color =
get_colors()" you see the try/except import statements. Since there is
no "foobar" named module, an ImportError should have been thrown and a
relevant error message should have been printed.
With these example I'm just trying to prove that imports put into a
class' __init__() never get executed. They get executed if you put
them in any of the methods. (And I don't know why it is done this
way).

Ritesh