Re: Need help to understand not the answer

[Rick Johnson]

On Saturday, July 29, 2017 at 2:16:36 PM UTC-5, new_to_c0ding wrote:
> Hello all, I have been scratching my head since morning but
> could not understand this quiz question. I would appreciate
> if someone could help me understand what is it asking me to
> do. I dont need the answer but just the right direction to
> look at.

Hello.

First of all, as i look over this "script template" that
your instructor has supposedly provided, i am disgusted by
the abysmal formatting. I'm not sure if what you provided
here is an exact replica, or something that you have
modified, but in either case, a little bit of proper
formatting can go a loong way towards readability.

For instance,

When writing in natural languages (such as English), we
utilize common structural elements and rules so that our
text will be presented in manner that is recognizable to
most readers. A few of these "high level structural
components" include _spaces_, _sentences_ and _paragraphs_.
And when writing code, we also utilize a "common structure".
And one of the most important components of this "common
structure" is the use of vertical whitespace. By properly
utilizing vertical whitespace, we can separate the
"paragraphs" of our code (aka: classes and functions) so
that reading the code will be more intuitive. 

Of course, 

Structuring code is far more complicated than simply
creating "visual buffers zones" around classes and
functions, and many hours have been spent debating what is
proper, and what is not. But being that in the "realms of
the OOP paradigm" classes and methods are the most
fundamental elements, it should come as no surprise that
mastering the formatting of these elements is a vital first
lesson.

Now,

Even though there is something of an "ideological war"
raging as to exactly how much vertical whitespace should be
used, and _where_ it should be used, most programmers will
agree that the following example is acceptable. A common
style is to place *ONE* vertical whitespace between each
method in a class,and two vertical whitespaces between the
classes themselves. Observe the following...

## BEGIN: READABLE CODE EXAMPLE ##

 class Location(object):
 """DOCSTRING MISSING!!!"""

 def __init__(self, x, y):
 self.x = x
 self.y = y

 def move(self, deltaX, deltaY):
 return Location(self.x + deltaX, self.y + deltaY)

 def getX(self):
 return self.x

 def getY(self):
 return self.y

 def dist_from(self, other):
 xDist = self.x - other.x
 yDist = self.y - other.y
 return (xDist**2 + yDist**2)**0.5

 def __eq__(self, other):
 return (self.x == other.x and self.y == other.y)

 def __str__(self):
 return '<' + str(self.x) + ',' + str(self.y) + '>'


 class Campus(object):
 """DOCSTRING MISSING!!!"""

 def __init__(self, center_loc):
 self.center_loc = center_loc

 def __str__(self):
 return str(self.center_loc)


 class MITCampus(Campus):
 """ A MITCampus is a Campus that contains tents """

 def __init__(self, center_loc, tent_loc=Location(0,0)):
 """ Assumes center_loc and tent_loc are Location objects
 Initializes a new Campus centered at location center_loc
 with a tent at location tent_loc """
 # Your code here

 def add_tent(self, new_tent_loc):
 """ Assumes new_tent_loc is a[n *INSTANCE* of] Location
 Adds new_tent_loc to the campus only if the tent is at least 0.5 
distance
 away from all other tents already there. Campus is unchanged otherwise.
 Returns True if it could add the tent, False otherwise. """
 # Your code here

 def remove_tent(self, tent_loc):
 """ Assumes tent_loc is a[n *INSTANCE* of] Location
 Removes tent_loc from the campus.
 Raises a ValueError if there is not a tent at tent_loc.
 Does not return anything """
 # Your code here

 def get_tents(self):
 """ Returns a list of all tents on the campus. The list should contain
 the string representation of the Location of a tent. The list should
 be sorted by the x coordinate of the location. """
 # Your code here

## END: READABLE CODE EXAMPLE ##

But what is most important to remember here is _not_ so much
the _number_ of spaces used, but that the number is greater
than _zero_, and that the spacing is _consistent_. For
instance: if one feels that two spaces between methods is
more desirable then that is okay, but, one should maintain
the two space buffer between *ALL* methods in the script
*AND* furthermore, expand the b

Re: Need help to understand not the answer

[devinderaujla]

On Saturday, July 29, 2017 at 3:49:55 PM UTC-4, MRAB wrote:
> On 2017-07-29 20:16, new_to_c0ding wrote:
> > Hello all,
> > I have been scratching my head since morning but could not understand this 
> > quiz question. I would appreciate if someone could help me understand what 
> > is it asking me to do. I dont need the answer but just the right direction 
> > to look at.
> > 
> > ### Do not change the Location or Campus classes. ###
> > ### Location class is the same as in lecture. ###
> > class Location(object):
> >  def __init__(self, x, y):
> >  self.x = x
> >  self.y = y
> >  def move(self, deltaX, deltaY):
> >  return Location(self.x + deltaX, self.y + deltaY)
> >  def getX(self):
> >  return self.x
> >  def getY(self):
> >  return self.y
> >  def dist_from(self, other):
> >  xDist = self.x - other.x
> >  yDist = self.y - other.y
> >  return (xDist**2 + yDist**2)**0.5
> >  def __eq__(self, other):
> >  return (self.x == other.x and self.y == other.y)
> >  def __str__(self):
> >  return '<' + str(self.x) + ',' + str(self.y) + '>'
> >  
> > class Campus(object):
> >  def __init__(self, center_loc):
> >  self.center_loc = center_loc
> >  def __str__(self):
> >  return str(self.center_loc)
> > class MITCampus(Campus):
> >  """ A MITCampus is a Campus that contains tents """
> >  def __init__(self, center_loc, tent_loc = Location(0,0)):
> >  """ Assumes center_loc and tent_loc are Location objects
> >  Initializes a new Campus centered at location center_loc
> >  with a tent at location tent_loc """
> >  # Your code here
> >
> >  def add_tent(self, new_tent_loc):
> >  """ Assumes new_tent_loc is a Location
> >  Adds new_tent_loc to the campus only if the tent is at least 0.5 
> > distance
> >  away from all other tents already there. Campus is unchanged 
> > otherwise.
> >  Returns True if it could add the tent, False otherwise. """
> >  # Your code here
> >
> >  def remove_tent(self, tent_loc):
> >  """ Assumes tent_loc is a Location
> >  Removes tent_loc from the campus.
> >  Raises a ValueError if there is not a tent at tent_loc.
> >  Does not return anything """
> >  # Your code here
> >
> >  def get_tents(self):
> >  """ Returns a list of all tents on the campus. The list should 
> > contain
> >  the string representation of the Location of a tent. The list 
> > should
> >  be sorted by the x coordinate of the location. """
> >  # Your code here
> > 
> > 
> > 
> > -=-=-=-=-=-=-=
> > 
> > For example, if c = MITCampus(Location(1,2)) then executing the following 
> > sequence of commands:
> > 
> > c.add_tent(Location(2,3)) should return True
> > c.add_tent(Location(1,2)) should return True
> > c.add_tent(Location(0,0)) should return False
> > c.add_tent(Location(2,3)) should return False
> > c.get_tents() should return ['<0,0>', '<1,2>', '<2,3>']
> > 
> > -=-=-=-=-=-=-
> > 
> > Now as per instructions, class MITCampus(Campus) has  (self, center_loc, 
> > tent_loc = Location(0,0)) and it is mentioned that center_loc and tent_loc 
> > are Location objects but when I code them as Locations, I get error from 
> > the tester:
> > Traceback (most recent call last):
> >File "submission.py", line 61, in __init__
> >  self.cloc=Location(center_loc)
> > TypeError: __init__() missing 1 required positional argument: 'y'
> > 
> > -=-=-=-==
> > 
> > Please help
> > 
> Location.__init__ expects 3 arguments: self, x, y
> 
> self is already provided, so that leaves 2 arguments: x, y
> 
> You're giving it only 1 argument: center_loc
> 
> What is center_loc? Is it a tuple?
> 
> If it is, then you could do:
> 
>  self.cloc=Location(center_loc[0], center_loc[1])
> 
> or:
> 
>  self.cloc=Location(*center_loc)

Hi, thanks for replying. As per the description it is a Location object. And 
that result is from the tester so it should have provided two values if it was 
expecting it to be a location object.
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Re: Need help to understand not the answer

[MRAB]

On 2017-07-29 20:16, new_to_c0ding wrote:

Hello all,
I have been scratching my head since morning but could not understand this quiz 
question. I would appreciate if someone could help me understand what is it 
asking me to do. I dont need the answer but just the right direction to look at.

### Do not change the Location or Campus classes. ###
### Location class is the same as in lecture. ###
class Location(object):
 def __init__(self, x, y):
 self.x = x
 self.y = y
 def move(self, deltaX, deltaY):
 return Location(self.x + deltaX, self.y + deltaY)
 def getX(self):
 return self.x
 def getY(self):
 return self.y
 def dist_from(self, other):
 xDist = self.x - other.x
 yDist = self.y - other.y
 return (xDist**2 + yDist**2)**0.5
 def __eq__(self, other):
 return (self.x == other.x and self.y == other.y)
 def __str__(self):
 return '<' + str(self.x) + ',' + str(self.y) + '>'
 
class Campus(object):

 def __init__(self, center_loc):
 self.center_loc = center_loc
 def __str__(self):
 return str(self.center_loc)
class MITCampus(Campus):
 """ A MITCampus is a Campus that contains tents """
 def __init__(self, center_loc, tent_loc = Location(0,0)):
 """ Assumes center_loc and tent_loc are Location objects
 Initializes a new Campus centered at location center_loc
 with a tent at location tent_loc """
 # Your code here
   
 def add_tent(self, new_tent_loc):

 """ Assumes new_tent_loc is a Location
 Adds new_tent_loc to the campus only if the tent is at least 0.5 
distance
 away from all other tents already there. Campus is unchanged otherwise.
 Returns True if it could add the tent, False otherwise. """
 # Your code here
   
 def remove_tent(self, tent_loc):

 """ Assumes tent_loc is a Location
 Removes tent_loc from the campus.
 Raises a ValueError if there is not a tent at tent_loc.
 Does not return anything """
 # Your code here
   
 def get_tents(self):

 """ Returns a list of all tents on the campus. The list should contain
 the string representation of the Location of a tent. The list should
 be sorted by the x coordinate of the location. """
 # Your code here



-=-=-=-=-=-=-=

For example, if c = MITCampus(Location(1,2)) then executing the following 
sequence of commands:

c.add_tent(Location(2,3)) should return True
c.add_tent(Location(1,2)) should return True
c.add_tent(Location(0,0)) should return False
c.add_tent(Location(2,3)) should return False
c.get_tents() should return ['<0,0>', '<1,2>', '<2,3>']

-=-=-=-=-=-=-

Now as per instructions, class MITCampus(Campus) has  (self, center_loc, 
tent_loc = Location(0,0)) and it is mentioned that center_loc and tent_loc are 
Location objects but when I code them as Locations, I get error from the tester:
Traceback (most recent call last):
   File "submission.py", line 61, in __init__
 self.cloc=Location(center_loc)
TypeError: __init__() missing 1 required positional argument: 'y'

-=-=-=-==

Please help


Location.__init__ expects 3 arguments: self, x, y

self is already provided, so that leaves 2 arguments: x, y

You're giving it only 1 argument: center_loc

What is center_loc? Is it a tuple?

If it is, then you could do:

self.cloc=Location(center_loc[0], center_loc[1])

or:

self.cloc=Location(*center_loc)
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Re: Need help to understand not the answer

[Piet van Oostrum]

new_to_c0ding  writes:

> Now as per instructions, class MITCampus(Campus) has  (self, center_loc, 
> tent_loc = Location(0,0)) and it is mentioned that center_loc and tent_loc 
> are Location objects but when I code them as Locations, I get error from the 
> tester:
> Traceback (most recent call last):
>   File "submission.py", line 61, in __init__
> self.cloc=Location(center_loc)
> TypeError: __init__() missing 1 required positional argument: 'y'

Location must be called with 2 parameters: a x and a y coordinate, not
with another location as parameter.
-- 
Piet van Oostrum 
WWW: http://piet.vanoostrum.org/
PGP key: [8DAE142BE17999C4]
-- 
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Need help to understand not the answer

[new_to_c0ding]

Hello all,
I have been scratching my head since morning but could not understand this quiz 
question. I would appreciate if someone could help me understand what is it 
asking me to do. I dont need the answer but just the right direction to look at.

### Do not change the Location or Campus classes. ###
### Location class is the same as in lecture. ###
class Location(object):
def __init__(self, x, y):
self.x = x
self.y = y
def move(self, deltaX, deltaY):
return Location(self.x + deltaX, self.y + deltaY)
def getX(self):
return self.x
def getY(self):
return self.y
def dist_from(self, other):
xDist = self.x - other.x
yDist = self.y - other.y
return (xDist**2 + yDist**2)**0.5
def __eq__(self, other):
return (self.x == other.x and self.y == other.y)
def __str__(self):
return '<' + str(self.x) + ',' + str(self.y) + '>'

class Campus(object):
def __init__(self, center_loc):
self.center_loc = center_loc
def __str__(self):
return str(self.center_loc)
class MITCampus(Campus):
""" A MITCampus is a Campus that contains tents """
def __init__(self, center_loc, tent_loc = Location(0,0)):
""" Assumes center_loc and tent_loc are Location objects 
Initializes a new Campus centered at location center_loc 
with a tent at location tent_loc """
# Your code here
  
def add_tent(self, new_tent_loc):
""" Assumes new_tent_loc is a Location
Adds new_tent_loc to the campus only if the tent is at least 0.5 
distance 
away from all other tents already there. Campus is unchanged otherwise.
Returns True if it could add the tent, False otherwise. """
# Your code here
  
def remove_tent(self, tent_loc):
""" Assumes tent_loc is a Location
Removes tent_loc from the campus. 
Raises a ValueError if there is not a tent at tent_loc.
Does not return anything """
# Your code here
  
def get_tents(self):
""" Returns a list of all tents on the campus. The list should contain 
the string representation of the Location of a tent. The list should 
be sorted by the x coordinate of the location. """
# Your code here



-=-=-=-=-=-=-=

For example, if c = MITCampus(Location(1,2)) then executing the following 
sequence of commands:

c.add_tent(Location(2,3)) should return True
c.add_tent(Location(1,2)) should return True
c.add_tent(Location(0,0)) should return False
c.add_tent(Location(2,3)) should return False
c.get_tents() should return ['<0,0>', '<1,2>', '<2,3>']

-=-=-=-=-=-=-

Now as per instructions, class MITCampus(Campus) has  (self, center_loc, 
tent_loc = Location(0,0)) and it is mentioned that center_loc and tent_loc are 
Location objects but when I code them as Locations, I get error from the tester:
Traceback (most recent call last):
  File "submission.py", line 61, in __init__
self.cloc=Location(center_loc)
TypeError: __init__() missing 1 required positional argument: 'y'

-=-=-=-==

Please help
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Re: Program prints questions for user input, but won't show the answer output

[Larry Hudson via Python-list]

On 05/18/2016 06:50 PM, Jake Kobs wrote:

MRAB,

I am not quite sure how to return the print statements so I thought that 
returning the displayInfo def would help.. Im so lost.

Why do you think you want to _return_ a print statement?  The print statement _DOES_ the 
printing, there is nothing that needs to be returned.  Sometimes you might want to return a 
_string_ to be printed where it was called from, but that's not what you want here.


You say that the display info isn't shown...  It looks to me like it it isn't shown because your 
program will crash.  What you have here is called "infinite recursion":


displayInfo() calls displayInfo() which calls displayInfo() which calls displayInfo() which 
calls ... and so on forever.


Another comment:  Your getHigh() and getLow() functions are not necessary.  Python already has 
max() and min() functions built in to do this exact same thing.  Instead you can use:


highPints = max(pints)
lowPints = min(pints)

Of course, writing your own versions as a leaning experience is good too.  But I would suggest 
that a for loop instead of a while in your version would be better.  For one thing, it 
eliminates the counter.  My suggested version...


def getHigh(pints):
high = 0
for pint in pints:
if pint > high:
high = pint
return high

And getLow() is similar (but set the initial value to a high number).

The following example may be more advanced than you're ready for now, but you _might_ find it 
worth studying.  It's possible to do both in a single function:


def getMaxMin(pints):
high = low = pints[0]#  Initialize high and low to the first value of 
the array
for pint in pints[1:]:   #  Scan through the remainder of the pints array
if pint > high:
high = pint
if pint < low:
low = pint
return high, low

You would use it as:

highPints, lowPints = getMaxMin(pints)

I'm NOT necessarily recommending this, but just suggesting it as an example to 
study.

Good luck with your Python studies.  It's a great language to learn.

 -=- Larry -=-

PS.  A final thought...

I don't know your situation so this may not be reasonable but...  I HIGHLY recommend switching 
to Python 3 instead of 2.  Version 2 is at "end-of-life" and won't be updated any further. 
Version 3 is where all future development will occur.  It is definitely the better version, and 
while there are certainly differences, to a beginning programmer the learning curve will be the 
same.


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Re: Program prints questions for user input, but won't show the answer output

[MRAB]

On 2016-05-19 02:50, Jake Kobs wrote:

MRAB,

I am not quite sure how to return the print statements so I thought that 
returning the displayInfo def would help.. Im so lost.


"return the print statements"?

The print statements ... print!

Have a search for Python tutorials online and pick one that suits you.

I see that you're using Python 2. I'd suggest trying Python 3 unless you 
have a good reason for using Python 2.


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Re: Program prints questions for user input, but won't show the answer output

[Steven D'Aprano]

On Thu, 19 May 2016 11:50 am, Jake Kobs wrote:

> MRAB,
> 
> I am not quite sure how to return the print statements so I thought that
> returning the displayInfo def would help.. Im so lost.

There's no need to return the text that you printed. You printed it, the job
is done.


Here is some general advice that may help you be less lost.

(1) Each function should do "one thing". For example, it either collects
information, or it displays it. It shouldn't do both. Your code seems
pretty good at following that guideline already, well done.

(2) Use existing functions as much as possible. The Python docs has a list
of the built-in functions here:

https://docs.python.org/2/library/functions.html

Refer to that as often as possible.

For example, your functions getHigh, getLow and getTotal functions just
re-invent the wheel. Python already has functions to do that:

max, min, sum

In Python 2, there's no built-in function for average, but for your purposes
you can just use sum(pints)/len(pints).

(3) Whoever taught you to write while loops should be taken out and
horse-whipped. While loops are for looping when you don't know in advance
how many times you need to repeat. When you do know how many times to
repeat, use a for-loop:

# I want to repeat seven times
for counter in range(7):
print "Loop", counter


Isn't that simpler than a while loop?

# I want to repeat seven times
counter = 7
while counter > 0:  # or should that be >= 0? >= 1? I forget!
print "Loop", counter
counter -= 1


And its faster too.


(4) Don't use "input". (The reasons are technical, if you really want to
know, please ask.) Instead of writing:

input("Enter pints collected: ")

write this:

int(raw_input("Enter pints collected: "))




-- 
Steven

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Re: Program prints questions for user input, but won't show the answer output

[Jake Kobs]

MRAB,

I am not quite sure how to return the print statements so I thought that 
returning the displayInfo def would help.. Im so lost.
-- 
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Re: Program prints questions for user input, but won't show the answer output

[MRAB]

On 2016-05-19 02:04, Jake Kobs wrote:

Here is the code:

#Lab 9-4 Blood Drive

#the main function
def main():
  endProgram = 'no'
  while endProgram == 'no':
print
# declare variables
pints = [0] * 7
totalPints = 0
averagePints = 0
highPints = 0
lowPints = 0












# function calls
pints = getPints(pints)
totalPints = getTotal(pints, totalPints)
averagePints = getAverage(totalPints, averagePints)
highPints = getHigh(pints, highPints)
lowPints = getLow(pints, lowPints)
displayInfo(averagePints, highPints, lowPints)

endProgram = raw_input('Do you want to end program? (Enter no or yes): ')
while not (endProgram == 'yes' or endProgram == 'no'):
  print 'Please enter a yes or no'
  endProgram = raw_input('Do you want to end program? (Enter no or yes): ')

#the getPints function
def getPints(pints):
counter = 0
while counter < 7:
pints[counter] = input("Enter pints collected: ")
counter = counter + 1
return pints
#the getTotal function
def getTotal(pints, totalPints):

counter = 0
while counter < 7:
totalPints = totalPints + pints[counter]
counter = counter + 1
return totalPints
#the getAverage function
def getAverage(totalPints, averagePints):
averagePints = totalPints / 7
return averagePints
#the getHigh function
def getHigh(pints, highPints):
highPints = pints[0]
counter = 1
while counter < 7:
if (pints[counter] > highPints):
highPints = pints[counter]


The indentation here is wrong:


counter = counter + 1


It will add 1 _only_ if pints[counter] > highPints.


return highPints
#the getLow function
def getLow(pints, lowPints):
lowPints = pints[0]
counter = 1
while counter < 7:
if (pints[counter] < lowPints):
lowPints = pints[counter]


The indentation here is wrong:


counter = counter + 1


It will add 1 _only_ if pints[counter] < highPints.


return lowPints
#the displayInfo function
def displayInfo(averagePints, highPints, lowPints):
print "The average pints donated was: ", averagePints
print "The highest amount of pints donated was: ", highPints
print "The lowest amount of pints donated was: ", lowPints


Why is 'displayInfo' calling itself here?


return displayInfo(averagePints, highPints, lowPints)

main()

The problem is that the display info isn't shown after the user types in their 
7 numerical values. Please help.



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Re: Program prints questions for user input, but won't show the answer output

[John Gordon]

In <1cc14787-7061-45c9-a70e-1b16e3f5e...@googlegroups.com> Jake Kobs 
 writes:

> Here is the code:

> def getHigh(pints, highPints):
> highPints = pints[0]
> counter = 1
> while counter < 7:
> if (pints[counter] > highPints):
> highPints = pints[counter]
> counter = counter + 1
> return highPints

getHigh() goes into an infinite loop if pints[counter] is less than or
equal to highPints.


> def getLow(pints, lowPints):
> lowPints = pints[0]
> counter = 1
> while counter < 7:
> if (pints[counter] < lowPints):
> lowPints = pints[counter]
> counter = counter + 1
> return lowPints

And getLow() has a very similar problem.

I suspect you want to unindent the 'counter = counter + 1' statement
so that it is NOT inside the 'if' statement.

-- 
John Gordon   A is for Amy, who fell down the stairs
gor...@panix.com  B is for Basil, assaulted by bears
-- Edward Gorey, "The Gashlycrumb Tinies"

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Program prints questions for user input, but won't show the answer output

[Jake Kobs]

Here is the code:

#Lab 9-4 Blood Drive

#the main function
def main():
  endProgram = 'no'
  while endProgram == 'no':
print 
# declare variables
pints = [0] * 7
totalPints = 0
averagePints = 0
highPints = 0
lowPints = 0






   





# function calls
pints = getPints(pints)
totalPints = getTotal(pints, totalPints)
averagePints = getAverage(totalPints, averagePints)
highPints = getHigh(pints, highPints)
lowPints = getLow(pints, lowPints)
displayInfo(averagePints, highPints, lowPints)
   
endProgram = raw_input('Do you want to end program? (Enter no or yes): ')
while not (endProgram == 'yes' or endProgram == 'no'):
  print 'Please enter a yes or no'
  endProgram = raw_input('Do you want to end program? (Enter no or yes): ')

#the getPints function
def getPints(pints):
counter = 0
while counter < 7: 
pints[counter] = input("Enter pints collected: ")
counter = counter + 1
return pints
#the getTotal function
def getTotal(pints, totalPints):

counter = 0
while counter < 7:
totalPints = totalPints + pints[counter]
counter = counter + 1
return totalPints
#the getAverage function
def getAverage(totalPints, averagePints):
averagePints = totalPints / 7
return averagePints
#the getHigh function
def getHigh(pints, highPints):
highPints = pints[0]
counter = 1
while counter < 7:
if (pints[counter] > highPints):
highPints = pints[counter]
counter = counter + 1
return highPints
#the getLow function
def getLow(pints, lowPints):
lowPints = pints[0]
counter = 1
while counter < 7:
if (pints[counter] < lowPints):
lowPints = pints[counter]
counter = counter + 1
return lowPints
#the displayInfo function
def displayInfo(averagePints, highPints, lowPints):
print "The average pints donated was: ", averagePints
print "The highest amount of pints donated was: ", highPints
print "The lowest amount of pints donated was: ", lowPints
return displayInfo(averagePints, highPints, lowPints)

main()

The problem is that the display info isn't shown after the user types in their 
7 numerical values. Please help.
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Re: [Tutor] Is context manager the answer to synchronous function calls?

[John Wong]

Ah. Thanks.. I removed the previous code. Please excuse me. I will rewrite
the question so it is clear.

Here is my current solution in an imperative way. My application will work
with AWS boto library to create EC2 instances and RDS instances. Assuming
my API will simply send the request, and return if the request is accepted,
I need to lock until the instance is ready before I can start the next
operation.

def create_vm(.):
# returns vm object

def modify_vm(.):
return new vm object

def get_vm_status(.):
return status


# NOTE: This is obviously a simplified version, but pretty much half
of the code.
def lock_until_ready(conn, get_status_func, _id, max_wait=60):
wait_count = 1
status = get_status_func(conn, _id)
while status != 'available' and wait_count < max_wait:
print("Querying status (attempt {i}): {status}".format(
i=wait_count, status=status))
wait_count += 1
time.sleep(10)
status = get_status_func(conn, _id)


def clone(data_center, image_id, options):

conn = get_connection(data_center)
vm_id = create_vm(conn, image_id, )
lock_until_ready(conn, get_vm_status, vm_id, max_wait=30)
modify_vm(conn, options)
lock_until_ready(conn, get_vm_status, vm_id, max_wait=30)


I hope this doesn't come across as a code review. This works. I made my
lock function extensible and testable, but I feel like there should be a
better more user-friendly way, even in the imperative world in Python. I
thought of context manager because I can do some clean up on entry (verify
the db name has not been taken), and exit (if fail rollback). If you are
familiar with cloudformation, it almost seems like that's what I am doing.
I am writing this because I have custom needs that cloudformation can't do
elegantly without many hops. API is much more flexible for my current task,
FYI.

Any feedback is welcome. Thank you.

John

On Wed, Sep 16, 2015 at 10:53 AM, Chris Angelico  wrote:

> On Thu, Sep 17, 2015 at 12:34 AM, John Wong  wrote:
> > Sorry first time posting to tutor / general list. Usually on TIP list. As
> > per Mark's recommendation, now posting to python-list@python.org.
>
> But, sadly, without a lot of context. When you change lists, it's
> helpful to include a lot of extra verbiage so folks who don't follow
> the other list can pick up where you were.
>
> ChrisA
> --
> https://mail.python.org/mailman/listinfo/python-list
>
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Re: [Tutor] Is context manager the answer to synchronous function calls?

[Chris Angelico]

On Thu, Sep 17, 2015 at 12:34 AM, John Wong  wrote:
> Sorry first time posting to tutor / general list. Usually on TIP list. As
> per Mark's recommendation, now posting to python-list@python.org.

But, sadly, without a lot of context. When you change lists, it's
helpful to include a lot of extra verbiage so folks who don't follow
the other list can pick up where you were.

ChrisA
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Re: [Tutor] Is context manager the answer to synchronous function calls?

[John Wong]

On Wed, Sep 16, 2015 at 7:54 AM, Mark Lawrence 
wrote:

>
> Assuming your (Alan's) guess is correct, and I certainly agree it's
> plausible, I suspect this might be better asked on the main Python mailing
> list, I don't see this as tutor material.
>
> Sorry first time posting to tutor / general list. Usually on TIP list. As
per Mark's recommendation, now posting to python-list@python.org.


On Wed, Sep 16, 2015 at 6:56 AM, Alan Gauld 
wrote:

>
> You don't actually specify but I'm guessing VM
> means Virtual Machine? Is it a specific type
> of VM? eg VMWare/VirtualBox or somesuch, or is
> it more of a sandbox environment like virtualenv?
> That might help us understand the restrictions better.


In my case my underlying functions will use boto (Amazon Web Service's
Python SDK) but I thought to abstract the details away from posting because
as you know I want to simply return an object. But yes, boto will simply
return the call with a response object. For example, to create an RDS
database, the call is returned and I will to query for the status of the
database before I can perform further actions to the instance such as
changing password (which is covered in the modify_vm function call). But
creating VM such as EC2 has an equal synchronous nature.

I would be tempted to use an asynchronous approach with a
> when_ready() function that takes my function as an input
> parameter. You could then run the when_ready in a thread
> or, I suspect, utilize the asyncio or asyncore modules,
> although I haven't tried using them for this kind of
> thing myself.
>
The bottom line is you need to wait for the status to
> change. How you do that wait is up to you but you can
> make it more readable for the user. The easier it is for
> the user the harder it will be for you.
>
>
Sounds like to make it readable and user friendly, also to have separation
of concern, I almost am locked into implementing in OOP style. Imperative
seems to be okay but lack the "shininess."

 Thank you.

John
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Re: I'm a newbie and you helped me find the answer...

[Dwight Hotmail]

Thank you, Jussi.

Problem finally solved.

I am using Coderunner 2 as my editor. It has a language setting. I had set
it as Python instead of Python 3.

Duh!

Thank you again, everyone!


With appreciation,

Dwight

dwi...@goldwinde.com
www.goldwinde.com

Author of the book, "Courage: the Choice that Makes the Difference--Your
Key to a Thousand Doors"

You can find all my books at http://www.couragebooks.key.to/

1-206-923-9554 (USA Telephone)
1-206-350-0129 (voice mail and fax U.S.A.)
86-153-9867-5712 (China Telephone)
goldwindedwight (Skype)
goldwinde (Wechat)
+8615398675712 (Whatsapp)
www.3forliving.key.to (daily living video playlist)
http://www.couragebooks.key.to/ (my books)



On 8/3/15, 5:49 PM, "Jussi Piitulainen"  wrote:

>Dwight GoldWinde quotes himself:
>>
>>> Okay, thank you, Dave, so I got the following info: type $(which
>>> python3)
>>> /Library/Frameworks/Python.framework/Versions/3.4/bin/python3 is
>>> /Library/Frameworks/Python.framework/Versions/3.4/bin/python3
>>>
>>> But I can¹t figure out what short of ³usr² statement
>>> (e.g. #!/usr/bin/env python3) I need to point it there. Whatever I
>>> tried, still gives me version 2.
>
>How are you launching your script? If your method involves clicking some
>pretty picture or something similar, you may be bypassing /usr/bin/env
>altogether and relying on some association of file types in Mac OS. Then
>you need to investigate file properties in Finder, or something like
>that. It should be safe to change the association for that individual
>script but not necessarily for all files with the same extension.
>
>If your method is to type "python scriptname" at the shell prompt, you
>are definitely bypassing /usr/bin/env and specifying the default python
>as the one to use. Solution: type "python3 scriptname" instead. (A more
>advanced solution: make scriptname executable and type "./scriptname"
>instead. This one uses /usr/bin/env to find the interpreter.)
>
>(You could try "#!/usr/bin/env aintgotnosuch" as your script's hashbang
>line to see if it even matters what that line says. Check first that you
>don't happen to have a program named "aintgotnosuch" in your path.)
>-- 
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the ressurection of ZOPE for web domination? bluebream and caveman the answer?

[johannes falcone]

i loved the rant about how zope would have all these features, and then some 
other python framework would come on with like 1 and act like its the bomb, and 
zope was like we been doing that and more for X years

those who dont study zope are doomed to repeat it!!!

is zope scoffing at drupal? botle? pyramid ?
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Re: The answer

[samwyse]

On Jan 17, 8:30 pm, Jive Dadson  wrote:
> Okay, with your help I've figured it out.  Instructions are below, but
> read the caveat by Ben Fenny in this thread.  All this stuff is good for
> one default version of Python only.  The PYTHONPATH described below, for
> example, cannot specify a version number.  Yes, that's a pain in the
> butt, but there's no way around it.  If you switch versions, you may
> have to delete all the .pyc files that will show up in the module
> folders.  Python ought to check them to see if they are valid, but I do
> not know if it does so.
>
> These instructions are for MS Windows.
>
> 1) Create your modules folder. Let's say it's named "Modules."  The
> documentation calls it a "package."
>
> 2) In an explorer window or on the desktop, right click on My Computer,
> and select Properties.
>
> 3) Select the Advanced tab, and click on Environment Variables near the
> bottom.
>
> 4) Look for an environment variable named PYTHONPATH.
>
>     a) If you do not find one, create one using the New button(s). I
> don't know if it has to be in User Variables or System Variables.  To
> save time experimenting, I just put one in both. For the value, put the
> full path of the folder Modules.
>
>     b) If there's already a PYTHONPATH,  Edit it, adding a semi-colon
> and the full path of folder Module to the end.
>
> 5) Put your module folders into the folder Module.
>
> 6) (Here's a really arcane bit.) Into each module folder, put a file
> named __init__.py.  It will be executed when you load the module.  It
> can be empty, but it has to be there or else the module folder will be
> ignored.

In your original thread, you never quite said why you can't use site-
packages and .pth files.  Are you not allowed to modify your local
installation?  If you are writing something for distribution to
others, then site-packages and .pth files are the best way to go,
since they don't assume any particular operating system.  If you can't
(or won't) use them, then just create Module as a sub-directory of
wherever your program lives, since that directory is always prepended
to PYTHONPATH.  If you need to use the same module from multiple
directories, most modern operating systems support symbolic links; if
you're using Windows, well, here's a nickel kid, get yourself a better
computer (http://farm1.static.flickr.com/
89/240711122_f9888e5a3b_o.jpg).

I don't think that __init__.py is very arcane, since it is described
in detail in the documentation.  It's also a great place to use the
standard site.addsitedir() function, which is another platform
independent way to manipulate Python's search path.
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Re: The answer

[Dave Angel]

Jive Dadson wrote:
alex23 
wrote:

>
> Actually, if you're using Python 2.6+/3.x, you can effectively skip
> steps 1-5, as these versions now support user site-packages.
>
> Rather than create a Module folder and modify your PYTHONPATH, add (if
> it doesn't exist already) the following folder:
> %APPDATA%/Python/Python26/site-packages
>
> Modules can sit directly in the folder, or within packages.
>
> For more details: http://www.python.org/dev/peps/pep-0370/

That requires a directory whose name embeds the Python version number, 
which is the evil from which I flee, or rather sought to flee.  
Imagine if all your C++ code had to go into directories that were 
named for some specific C++ compiler.  It's just WRONG.  It's a 
maintenance nightmare to have a bunch of different source files that 
all have to be updated whenever you fix a bug or add a feature.



As others have pointed out, you need a "deploy" script, which in your 
case would copy the files from source control to the appropriate 
production folder.  That's analogous to the compile, link and deploy 
steps of C++.  And if you want to be even more analogous, copy just the 
.pyc files, after building them.


Certainly you have lots more files in your version control system which 
are not intended to be copied to the "Modules" folder, such as the test 
suite.


DaveA

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Re: The answer

[Lie Ryan]

On 01/18/10 13:30, Jive Dadson wrote:
> Okay, with your help I've figured it out.  Instructions are below, but
> read the caveat by Ben Fenny in this thread.  All this stuff is good for
> one default version of Python only.  The PYTHONPATH described below, for
> example, cannot specify a version number.  Yes, that's a pain in the
> butt, but there's no way around it.  If you switch versions, you may
> have to delete all the .pyc files that will show up in the module
> folders.  Python ought to check them to see if they are valid, but I do
> not know if it does so.

Err... "The answer" to... what?
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Re: The answer

[alex23]

Jive Dadson  wrote:
> That requires a directory whose name embeds the Python version number,
> which is the evil from which I flee, or rather sought to flee.  Imagine
> if all your C++ code had to go into directories that were named for some
> specific C++ compiler.  It's just WRONG.  It's a maintenance nightmare
> to have a bunch of different source files that all have to be updated
> whenever you fix a bug or add a feature.

With the PEP 370 approach, you can just designate a folder the core
one and symlink all other versions to it. Or better yet, use version
control to push updates to each folder.

With all of the versions sharing one folder, as you'd prefer, it would
be a lot more difficult to actually achieve version-level granularity
if and when you need it. It's not WRONG, it's just providing a level
of control that you don't need at this point.
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Re: The answer

[Jive Dadson]

alex23 wrote:
>
> Actually, if you're using Python 2.6+/3.x, you can effectively skip
> steps 1-5, as these versions now support user site-packages.
>
> Rather than create a Module folder and modify your PYTHONPATH, add (if
> it doesn't exist already) the following folder:
> %APPDATA%/Python/Python26/site-packages
>
> Modules can sit directly in the folder, or within packages.
>
> For more details: http://www.python.org/dev/peps/pep-0370/

That requires a directory whose name embeds the Python version number, 
which is the evil from which I flee, or rather sought to flee.  Imagine 
if all your C++ code had to go into directories that were named for some 
specific C++ compiler.  It's just WRONG.  It's a maintenance nightmare 
to have a bunch of different source files that all have to be updated 
whenever you fix a bug or add a feature.

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Re: The answer

[alex23]

On Jan 18, 12:30 pm, Jive Dadson  wrote:
> These instructions are for MS Windows.
>
> 1) Create your modules folder. Let's say it's named "Modules."  The
> documentation calls it a "package."
>
> 2) In an explorer window or on the desktop, right click on My Computer,
> and select Properties.
>
> 3) Select the Advanced tab, and click on Environment Variables near the
> bottom.
>
> 4) Look for an environment variable named PYTHONPATH.
>
>     a) If you do not find one, create one using the New button(s). I
> don't know if it has to be in User Variables or System Variables.  To
> save time experimenting, I just put one in both. For the value, put the
> full path of the folder Modules.
>
>     b) If there's already a PYTHONPATH,  Edit it, adding a semi-colon
> and the full path of folder Module to the end.
>
> 5) Put your module folders into the folder Module.
>
> 6) (Here's a really arcane bit.) Into each module folder, put a file
> named __init__.py.  It will be executed when you load the module.  It
> can be empty, but it has to be there or else the module folder will be
> ignored.

Actually, if you're using Python 2.6+/3.x, you can effectively skip
steps 1-5, as these versions now support user site-packages.

Rather than create a Module folder and modify your PYTHONPATH, add (if
it doesn't exist already) the following folder:
%APPDATA%/Python/Python26/site-packages

Modules can sit directly in the folder, or within packages.

For more details: http://www.python.org/dev/peps/pep-0370/
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Re: The answer

[Alf P. Steinbach]

* Jive Dadson:
Okay, with your help I've figured it out.  Instructions are below, but 
read the caveat by Ben Fenny in this thread.  All this stuff is good for 
one default version of Python only.  The PYTHONPATH described below, for 
example, cannot specify a version number.  Yes, that's a pain in the 
butt, but there's no way around it.  If you switch versions, you may 
have to delete all the .pyc files that will show up in the module 
folders.  Python ought to check them to see if they are valid, but I do 
not know if it does so.


These instructions are for MS Windows.

1) Create your modules folder. Let's say it's named "Modules."  The 
documentation calls it a "package."


2) In an explorer window or on the desktop, right click on My Computer, 
and select Properties.


3) Select the Advanced tab, and click on Environment Variables near the 
bottom.


4) Look for an environment variable named PYTHONPATH.

   a) If you do not find one, create one using the New button(s). I 
don't know if it has to be in User Variables or System Variables.  To 
save time experimenting, I just put one in both. For the value, put the 
full path of the folder Modules.


The User variables /override/ the System variables for a given user. The System 
variables provide defaults for all users. One notable exception is PATH, where 
the User PATH items are appended to the System PATH.


Anyways, with many items in a variable like PATH it can be impractical to use 
Windows' functionality, which presents it all on one line, which for a PATH with 
many items can be exceeding long  --  like a many thousand characters[1] line.


So for your convenience, below is a little Windows app (as an HTML application, 
it's just some HTML and VBScript and CSS) that presents the user PATH items one 
per line in a Notepad-like window. It should be no problem modifying it to 
instead edit PYTHONPATH, or even a choice of environment variable. As my late 
father used to say, when you don't have a tool, you make it.


Maybe now I should recode this in Python. But on the other hand, one shouldn't 
spend time fixing what works.  So  ... enjoy! :-)


Note: it's crucial to use [.HTA] filename extension.
Also, it's quite possible that this doesn't work in Windows Vista (at least not 
without configuration of Windows), but it works in XP and earlier.








content="http://schemas.microsoft.com/intellisense/ie5";>





Simple user-environment %path% editor


body{ margin: 0px; padding: 0px; }

#menuArea
{
width: 100%; height: 1.8em; white-space: nowrap; padding-top: 
2px;
background: #E0E0E0;
}

#clientArea
{
width: 100%; position: absolute; top: 1.8em; bottom: 0;
}

#pathEditor
{
display: inline-block;
width: 100%; height: 100%;
border: 0;
position: absolute; top: 0;
overflow: scroll;
}



option explicit
dim wshShell
dim wshUserEnv
dim originalText

sub loadText

The answer

[Jive Dadson]

Okay, with your help I've figured it out.  Instructions are below, but 
read the caveat by Ben Fenny in this thread.  All this stuff is good for 
one default version of Python only.  The PYTHONPATH described below, for 
example, cannot specify a version number.  Yes, that's a pain in the 
butt, but there's no way around it.  If you switch versions, you may 
have to delete all the .pyc files that will show up in the module 
folders.  Python ought to check them to see if they are valid, but I do 
not know if it does so.


These instructions are for MS Windows.

1) Create your modules folder. Let's say it's named "Modules."  The 
documentation calls it a "package."


2) In an explorer window or on the desktop, right click on My Computer, 
and select Properties.


3) Select the Advanced tab, and click on Environment Variables near the 
bottom.


4) Look for an environment variable named PYTHONPATH.

   a) If you do not find one, create one using the New button(s). I 
don't know if it has to be in User Variables or System Variables.  To 
save time experimenting, I just put one in both. For the value, put the 
full path of the folder Modules.


   b) If there's already a PYTHONPATH,  Edit it, adding a semi-colon 
and the full path of folder Module to the end.


5) Put your module folders into the folder Module.

6) (Here's a really arcane bit.) Into each module folder, put a file 
named __init__.py.  It will be executed when you load the module.  It 
can be empty, but it has to be there or else the module folder will be 
ignored.

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The answer

[Jive Dadson]

Okay, with your help I've figured it out.  Instructions are below, but 
read the caveat by Ben Fenny in this thread.  All this stuff is good for 
one default version of Python only.  The PYTHONPATH described below, for 
example, cannot specify a version number.  Yes, that's a pain in the 
butt, but there's no way around it.  If you switch versions, you may 
have to delete all the .pyc files that will show up in the module 
folders.  Python ought to check them to see if they are valid, but I do 
not know if it does so.


These instructions are for MS Windows.

1) Create your modules folder. Let's say it's named "Modules."  The 
documentation calls it a "package."


2) In an explorer window or on the desktop, right click on My Computer, 
and select Properties.


3) Select the Advanced tab, and click on Environment Variables near the 
bottom.


4) Look for an environment variable named PYTHONPATH.

   a) If you do not find one, create one using the New button(s). I 
don't know if it has to be in User Variables or System Variables.  To 
save time experimenting, I just put one in both. For the value, put the 
full path of the folder Modules.


   b) If there's already a PYTHONPATH,  Edit it, adding a semi-colon 
and the full path of folder Module to the end.


5) Put your module folders into the folder Module.

6) (Here's a really arcane bit.) Into each module folder, put a file 
named __init__.py.  It will be executed when you load the module.  It 
can be empty, but it has to be there or else the module folder will be 
ignored.

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Re: Help me in this please--is Python the answer?

[Adrian Holovaty]

Ray wrote:
> Does the comparison between dynamic and static language carry over to
> comparison between Django and Turbogear too? Is this what is meant by
> "Turbogear is much more flexible than Django"?

Nah, the difference is more than Django is a complete product whereas
TurboGears is a collection of unrelated parts glued together. For more
on this topic, see here:

http://www.oreillynet.com/pub/wlg/8986

Adrian

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Re: Help me in this please--is Python the answer?

[Ray]

Fredrik Lundh wrote:
> I hope you're aware that this sounds a lot like late 90's anti-dynamic-
> language propaganda...
>
> "I would never use Perl or Python over C++ for any performance-
> "intensive Web app. In my opinion, both languages make some
> poor design decisions regarding the importance of performance."
>
> (you all know all the counter-arguments)

Does the comparison between dynamic and static language carry over to
comparison between Django and Turbogear too? Is this what is meant by
"Turbogear is much more flexible than Django"?

Thanks,
Ray

> 
> 

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Re: Help me in this please--is Python the answer?

[Fredrik Lundh]

Adrian Holovaty wrote:

> I would never use TurboGears or Ruby on Rails over Django for any
> performance-intensive Web app. In my opinion, both frameworks make some
> poor design decisions regarding the importance of performance.

I hope you're aware that this sounds a lot like late 90's anti-dynamic-
language propaganda...

"I would never use Perl or Python over C++ for any performance-
"intensive Web app. In my opinion, both languages make some
poor design decisions regarding the importance of performance."

(you all know all the counter-arguments)





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Re: Help me in this please--is Python the answer?

[Ray]

bruno at modulix wrote:
> Possibly - but if a programmer is not able to pick on Python in a matter
> of days, then it's a bad programmer that won't be of any help whatever
> the language. So in fact, choosing Python may help you get better
> programmers !-)

You have a point there! :)

> You may also want to have a look at turbogears (roughly similar to
> Django, but probably much more flexible)

Hmm--much more flexible in what sense, Bruno?

Thanks much!
Ray

>
> My 2 cents
> --
> bruno desthuilliers
> python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
> p in '[EMAIL PROTECTED]'.split('@')])"

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Re: Help me in this please--is Python the answer?

[Ray]

Very useful input, Adrian.

Thanks a lot! These are facts that I can use to convince people that
Python is a legit choice for the app I'm developing.

Warm regards,
Ray

Adrian  Holovaty wrote:
> Ray wrote:
> > Yes, but this is more of a web application though--something that I've
> > never developed in Python before, so... I'll be evaluating Django
> > shortly--let me see how it compares to Tomcat.
>
> Performance is one of the key features of Django. For example, I'm
> using Django at washingtonpost.com for the U.S. Congress Votes
> Database, which has more than 4 million records and is linked-to from
> the washingtonpost.com home page whenever there's a key congressional
> vote. (http://projects.washingtonpost.com/congress/)
>
> The server doesn't break a sweat, thanks to Django's
> very-convenient-and-powerful cache system:
> http://www.djangoproject.com/documentation/cache/
>
> Also, the developers at grono.net, a Polish social networking site with
> more than half a million users, have converted various bits of their
> Java code to Python/Django. They've found that Django is not only much
> quicker (and more fun) to develop in, it's also *faster* than Java and
> requires less hardware. E-mail me personally if you want their contact
> information for direct testimonials; we'll be publishing some more
> testimonials publically as we get closer to Django 1.0.
>
> I would never use TurboGears or Ruby on Rails over Django for any
> performance-intensive Web app. In my opinion, both frameworks make some
> poor design decisions regarding the importance of performance.
>
> Adrian
> --
> Adrian Holovaty
> holovaty.com | chicagocrime.org | djangoproject.com

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Re: Help me in this please--is Python the answer?

[Aahz]

In article <[EMAIL PROTECTED]>,
Tim N. van der Leeuw <[EMAIL PROTECTED]> wrote:
>
>- Do you have to interface with things like messaging-systems (a la JMS
>specs), distributed transaction managers? If so, the only way to go
>Python is Jython: Python for the JVM. Because AFAIK, there are no
>interfaces for Python to the likes of IBM's MQSeries or for any
>distributed transaction managers.

What about http://www.zope.org/Members/tim_one/spread/
-- 
Aahz ([EMAIL PROTECTED])   <*> http://www.pythoncraft.com/

"19. A language that doesn't affect the way you think about programming,
is not worth knowing."  --Alan Perlis
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Re: Help me in this please--is Python the answer?

[Adrian Holovaty]

Ray wrote:
> Yes, but this is more of a web application though--something that I've
> never developed in Python before, so... I'll be evaluating Django
> shortly--let me see how it compares to Tomcat.

Performance is one of the key features of Django. For example, I'm
using Django at washingtonpost.com for the U.S. Congress Votes
Database, which has more than 4 million records and is linked-to from
the washingtonpost.com home page whenever there's a key congressional
vote. (http://projects.washingtonpost.com/congress/)

The server doesn't break a sweat, thanks to Django's
very-convenient-and-powerful cache system:
http://www.djangoproject.com/documentation/cache/

Also, the developers at grono.net, a Polish social networking site with
more than half a million users, have converted various bits of their
Java code to Python/Django. They've found that Django is not only much
quicker (and more fun) to develop in, it's also *faster* than Java and
requires less hardware. E-mail me personally if you want their contact
information for direct testimonials; we'll be publishing some more
testimonials publically as we get closer to Django 1.0.

I would never use TurboGears or Ruby on Rails over Django for any
performance-intensive Web app. In my opinion, both frameworks make some
poor design decisions regarding the importance of performance.

Adrian
--
Adrian Holovaty
holovaty.com | chicagocrime.org | djangoproject.com

-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Help me in this please--is Python the answer?

[bruno at modulix]

Ray wrote:

(snip)
> But then on the other hand, there is a manpower problem--it's damn easy
> to find a Java programmer (although the quality that you get is a
> different matter). Python programmers are more difficult.

Possibly - but if a programmer is not able to pick on Python in a matter
of days, then it's a bad programmer that won't be of any help whatever
the language. So in fact, choosing Python may help you get better
programmers !-)

> 
>>If I were you I'd concentrate on creating a website that actually
>>works.  Your chances of creating a website that needs to scale to be
>>'heavyweight' are very slim.  If you manage to get to that point then
>>you can start worrying about how to cope with all the money that's
>>rolling in ;)
> 
> 
> You know what, this is a very good point :))
> 
> 
>>AFAIAA Python scales better than Java as any performance critical
>>parts can be easily rewritten in C.  To spend too much time worrying
>>over it is premature optimisation though.
> 
> 
> Yes, but this is more of a web application though--something that I've
> never developed in Python before, so... I'll be evaluating Django
> shortly--let me see how it compares to Tomcat.

You may also want to have a look at turbogears (roughly similar to
Django, but probably much more flexible)

My 2 cents
-- 
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])"
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Re: Help me in this please--is Python the answer?

[Ray]

Tim N. van der Leeuw wrote:
> Hi Ray,

Hi Tim!

> I'm in a bit of the same boat as you only I don't get to choose my
> implementation language ;-)
>
> Some of the concerns should be:
> - Do you have to interface with things like messaging-systems (a la JMS
> specs), distributed transaction managers? If so, the only way to go
> Python is Jython: Python for the JVM. Because AFAIK, there are no
> interfaces for Python to the likes of IBM's MQSeries or for any
> distributed transaction managers.

Hmmm, at this level I think not. But yes, this is a good point, I'll
keep this in mind. If it's gonna be Jython, I think I might as well go
with J2EE--since it is yet another layer on top of a platform.

> - Is your application purely a web-based application? Or is there a
> large amount of application logic which is not tied to the web in any
> way?

Yes, it is purely a web-based application... well, it has a
"administration" page, that the back office stuff, but that can be
web-based as well.

> - Python has a number of frameworks for developing server applications,
> like Twisted, Zope and Django.
> I don't know Twisted; I know a little bit about Zope. Zope has several
> enterprise-level features and provides scalability/clustering.
> However, I've found the learning-curve for Zope to be a bit steep so
> far; too steep to master it in what little bits of spare time I have.
> (If I would have more time I'd be able to get the hang of it but I
> don't have enough time)

Ah, yes... all respect to Zope, but I hope this is something that can
be done in Django. I suspect the implementation time will be very, very
short... as typical of the nature of these projects, and with the
seeming intricacies of Zope, the impression of which I get from reading
about it, I don't think we have the spare time/effort...

> I've started to toy a bit with Django and it seems to get rather easy
> to get started with developing a Web application using Django; however
> I also get the feeling that installation is a bit more involved than
> with Zope and that it will be not as easy to package up an application
> and transport it to another machine, as it is with Zope.

Thanks, this is a useful info. I'm about to evaluate Django deeper
myself, how have you found it? Does it cover the whole "web" part of
the J2EE stack, at least? (i.e.: it can replace Tomcat)? How has your
experience been when you need to go further? (i.e.: beyond mapping data
in DB to webpages)?

> So for development of Web-applications, I would certainly consider
> either Zope or Django.
> Both offer ways to store your data in a transactional database; Django
> has some object-relation mapper tools but I'm not sure how exactly Zope
> stores data in a SQL database (it comes with it's own powerful
> object-database, the ZODB but I don't know if OR mapping tools exist
> for Zope).

Hmm, I've never got the time to look at Zope proper, but my
understanding is that Django is analogous to Tomcat, and Zope is
analogous to a full blown appserver a la WebLogic, right?

> So what are your requirements for 'J2EE' applications? And which Python
> framework would best fit the bill?

Hmmm, it's purely web-based, and I don't foresee message queueing and
stuff at this point. I'll take a better look at Django.

Thanks!
Ray

> 
> 
> cheers,
> 
> --Tim

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Re: Help me in this please--is Python the answer?

[Ray]

Hi Ed,

Ed Singleton wrote:
> Personally I have found that if you need to sell a technology on,
> saying it's written in Java is an advantage generally (because "it's a
> standard").  If it's written in Python you may get asked why it has
> been written in a "scripting language" if they've heard of it at all.

Yes, I agree. Especially with those cover-my-ass types in big
institutions who'd only go for things that have the word "Enterprise"
on it :)

> exactly the same tools as them, so you have to choose better tools.
> Almost by definition, the tools that the majority are using are NOT
> the best tools for the job.  If I were you I'd definitely choose
> Python, if only because everyone else is not using it yet.

Yes, that was what I was thinking. Fast development cycle and ability
to embrace change is crucial here. I do feel the way Java is getting in
the way of my coding even after using Python for small personal
projects.

But then on the other hand, there is a manpower problem--it's damn easy
to find a Java programmer (although the quality that you get is a
different matter). Python programmers are more difficult.

> If I were you I'd concentrate on creating a website that actually
> works.  Your chances of creating a website that needs to scale to be
> 'heavyweight' are very slim.  If you manage to get to that point then
> you can start worrying about how to cope with all the money that's
> rolling in ;)

You know what, this is a very good point :))

> AFAIAA Python scales better than Java as any performance critical
> parts can be easily rewritten in C.  To spend too much time worrying
> over it is premature optimisation though.

Yes, but this is more of a web application though--something that I've
never developed in Python before, so... I'll be evaluating Django
shortly--let me see how it compares to Tomcat.

> > (I'd love to develop in Python and get paid for it finally, but at the
> > same time I do want to give the money guy the best value for his
> > money...)
>
> The only thing you really need to be happy is to find something you
> enjoy doing and to do it.  Money is definitely secondary to that.  If
> you have a chance to be paid for working in Python, then go for it;
> even if you fail, you will have spent your days in a happy state.

Yeah, I have the chance to do that if I manage to get this through, but
at the same time I do want to give the guy who funds us the best value
possible for his money. (If--If--it means I have to use J2EE, I will do
it.)

Thanks,
Ray

> 
> Ed

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Re: Help me in this please--is Python the answer?

[Ed Singleton]

On 11 Jan 2006 17:54:05 -0800, Ray <[EMAIL PROTECTED]> wrote:
> Hello,
>
> I've got the chance to determine the technology to use in creating a
> product similar to this:
>
> http://www.atomicisland.com/
>
> Now the thing is that I need to sell this to the guy with the money.
> I've developed for years with C++ and Java, last 7 years J2EE, and I'm
> kinda sick of the "bloated" feeling that the whole J2EE/appserver
> business carries into the picture.

Personally I have found that if you need to sell a technology on,
saying it's written in Java is an advantage generally (because "it's a
standard").  If it's written in Python you may get asked why it has
been written in a "scripting language" if they've heard of it at all.

> Python is the language that I use at home, so I've been thinking of
> using this to implement the product mentioned above. I've personally
> experienced the pleasure of programming in it, and as such, I hope that
> this will translate to advantage over our competitors (a la Paul
> Graham's argument for Lisp).

>From my brief look at that url you gave, it looks like you are trying
to enter a very crowded market place.  You will have to perform a lot
better than your competitors in order to succeed (they have a head
start on you).  There's no way on earth you can do that by using
exactly the same tools as them, so you have to choose better tools. 
Almost by definition, the tools that the majority are using are NOT
the best tools for the job.  If I were you I'd definitely choose
Python, if only because everyone else is not using it yet.

> That said, my experience with Python is limited to toy programs, that I
> write myself for my own use. As such, I have several concerns:
>
> 1. How scalable is Python? In J2EE, when the load gets really big, we
> can resort to clustering. Same goes about availability. Is there
> anything that will help here in Python? (Mind, my Python experience is
> usually with scripts and console).
>
> 2. If there is, what is the transition like from being lightweight to
> heavyweight? E.g.: in J2EE we can use Tomcat at first as a lightweight
> web container, and scale as necessary using a more powerful appserver.
> Is this possible in Python?

If I were you I'd concentrate on creating a website that actually
works.  Your chances of creating a website that needs to scale to be
'heavyweight' are very slim.  If you manage to get to that point then
you can start worrying about how to cope with all the money that's
rolling in ;)

AFAIAA Python scales better than Java as any performance critical
parts can be easily rewritten in C.  To spend too much time worrying
over it is premature optimisation though.

> 3. Have any of you done this before? As in you come from a heavy J2EE
> background, and then switch to doing something equally serious in
> Python? In your experience, in the end, did you find Python suitable at
> all for this domain or you think you should have stuck to J2EE? What
> are the pros and cons you discovered?

I don't have much experience of Java tbh, but I've never heard of any
pro's to using it, except for the fact that it's more acceptable to
big business and it's easier to get mediocre programmers for it.

> (I'd love to develop in Python and get paid for it finally, but at the
> same time I do want to give the money guy the best value for his
> money...)

The only thing you really need to be happy is to find something you
enjoy doing and to do it.  Money is definitely secondary to that.  If
you have a chance to be paid for working in Python, then go for it;
even if you fail, you will have spent your days in a happy state.

Ed
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Help me in this please--is Python the answer?

[Tim N. van der Leeuw]

Hi Ray,

I'm in a bit of the same boat as you only I don't get to choose my
implementation language ;-)

Some of the concerns should be:
- Do you have to interface with things like messaging-systems (a la JMS
specs), distributed transaction managers? If so, the only way to go
Python is Jython: Python for the JVM. Because AFAIK, there are no
interfaces for Python to the likes of IBM's MQSeries or for any
distributed transaction managers.

- Is your application purely a web-based application? Or is there a
large amount of application logic which is not tied to the web in any
way?

- Python has a number of frameworks for developing server applications,
like Twisted, Zope and Django.
I don't know Twisted; I know a little bit about Zope. Zope has several
enterprise-level features and provides scalability/clustering.
However, I've found the learning-curve for Zope to be a bit steep so
far; too steep to master it in what little bits of spare time I have.
(If I would have more time I'd be able to get the hang of it but I
don't have enough time)

I've started to toy a bit with Django and it seems to get rather easy
to get started with developing a Web application using Django; however
I also get the feeling that installation is a bit more involved than
with Zope and that it will be not as easy to package up an application
and transport it to another machine, as it is with Zope.


So for development of Web-applications, I would certainly consider
either Zope or Django.
Both offer ways to store your data in a transactional database; Django
has some object-relation mapper tools but I'm not sure how exactly Zope
stores data in a SQL database (it comes with it's own powerful
object-database, the ZODB but I don't know if OR mapping tools exist
for Zope).


However you mentioned 'development in J2EE' and J2EE applications are
by no means restricted to Web interfaces. J2EE applications can have
rich GUI clients, or can be without any UI at all and exist just as
message-driven beans triggered by messages coming in via JMS
interfaces.
I wouldn't know what Python frameworks exist that would combine
web-based applications with tradional GUI client/server applications
and I have no idea how to listen to a queue using Python...


So what are your requirements for 'J2EE' applications? And which Python
framework would best fit the bill?


cheers,

--Tim

-- 
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Help me in this please--is Python the answer?

[Ray]

Hello,

I've got the chance to determine the technology to use in creating a
product similar to this:

http://www.atomicisland.com/

Now the thing is that I need to sell this to the guy with the money.
I've developed for years with C++ and Java, last 7 years J2EE, and I'm
kinda sick of the "bloated" feeling that the whole J2EE/appserver
business carries into the picture.

Python is the language that I use at home, so I've been thinking of
using this to implement the product mentioned above. I've personally
experienced the pleasure of programming in it, and as such, I hope that
this will translate to advantage over our competitors (a la Paul
Graham's argument for Lisp).

That said, my experience with Python is limited to toy programs, that I
write myself for my own use. As such, I have several concerns:

1. How scalable is Python? In J2EE, when the load gets really big, we
can resort to clustering. Same goes about availability. Is there
anything that will help here in Python? (Mind, my Python experience is
usually with scripts and console).

2. If there is, what is the transition like from being lightweight to
heavyweight? E.g.: in J2EE we can use Tomcat at first as a lightweight
web container, and scale as necessary using a more powerful appserver.
Is this possible in Python?

3. Have any of you done this before? As in you come from a heavy J2EE
background, and then switch to doing something equally serious in
Python? In your experience, in the end, did you find Python suitable at
all for this domain or you think you should have stuck to J2EE? What
are the pros and cons you discovered?

(I'd love to develop in Python and get paid for it finally, but at the
same time I do want to give the money guy the best value for his
money...)

Thanks much,
Ray

-- 
http://mail.python.org/mailman/listinfo/python-list