from:"Christopher"


Greetings,

Thanks to everyone for providing feedback. Here's my revised code to 
generate a set of chess pieces.



class PieceFactory(object):

def factory(color, piece, position):
if piece == 'Bishop':
return Bishop(color, position)
if piece == 'King':
return King(color, position)
if piece == 'Knight':
return Knight(color, position)
if piece == 'Pawn':
return Pawn(color, position)
if piece == 'Queen':
return Queen(color, position)
if piece == 'Rook':
return Rook(color, position)

raise PieceException('No valid Piece object for factory, 
got {}'

 ' instead'.format(piece))

factory = staticmethod(factory)


def generate_set(color, pieces, positions):

for piece, position in zip(pieces, positions):
yield getattr(PieceFactory, 'factory')(color, piece, position)


The input values for 'pieces' and 'positions' are 16-item lists zipped 
together to produce a piece name and a position coordinate for the 
factory method. With slight modifications to the code, the factory 
method could also return checker pieces.


I got the factory method from here: 
http://python-3-patterns-idioms-test.readthedocs.org/en/latest/Factory.html


I do plan to incorporate a sanity test in each Piece class to validate 
the initial position value. Pawns have 16 specific positions. Bishop, 
Knight and Rook each have four specific positions. King and Queen each 
have two specific positions. An invalid value will raise an exception.


Finally, VARS['VARIABLE_NAME'] got change to const['variable_name']. 
Should smell better.


Thanks,

Chris R

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Re: How much sanity checking is required for function inputs?


On 4/21/2016 6:54 PM, Tim Chase wrote:


I'd simplify this code to something like

   class PieceFactory(object):
 @staticmethod
 def factory(color, piece, position):
   try:
 return {
   'Bishop': Bishop,
   'King': King,
   'Knight': Knight,
   'Pawn': Pawn,
   'Queen': Queen,
   'Rook': Rook,
   }[piece](color, position)
   except KeyError:
 raise PieceException(...)


I like this better. I'll probably remove the try/except and let the 
KeyError filter up.


Thanks,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/21/2016 7:10 PM, Ethan Furman wrote:

I do plan to incorporate a sanity test in each Piece class to validate
the initial position value. Pawns have 16 specific positions. Bishop,
Knight and Rook each have four specific positions. King and Queen each
have two specific positions. An invalid value will raise an exception.


This will make it so you cannot use your PieceFactory for custom setups.



The sanity check won't be in the PieceFactory, but in the Piece class as 
an interface and each Piece subclass will implement the correct 
positions for comparison.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/21/2016 7:20 PM, Stephen Hansen wrote:
Whyyy are you using getattr? Something wrong with 
PieceFactory.factory(color, piece, position)? (Or, better yet, yield 
piece_factory(color, piece, position) where piece_factory is just a 
function)


Because the example I found used it, I implemented it, and it worked in 
my code. Based on feedback that I gotten from this list, I'll go back 
and clean it up.



I... that... what... I'd forget that link and pretend you never went
there. Its not helpful.


I found it on the Internet, so it must be true -- and Pythonic at that!

What's the contents of this big dictionary that has everything in it 
for some reason?


Keep in mind that I'm coming from a Java background (not by choice) with 
a smattering of C programming. I initially had ALL THESE CONSTANTS in 
different parts of my code and couldn't easily use them across different 
modules. I didn't like all these constants, created a singleton class 
that uses ConfigParser, dumped everything into a .ini file, and accessed 
from in each module. As I learn to write Pythonic code, the constants 
may go away. Switching from my original code to the factory method 
eliminated a half-dozen constants.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/21/2016 9:46 PM, Ethan Furman wrote:

Oh! and Enum!!!  ;)


OMG! I totally forgot about Enum. Oh, look. Python supports Enum. Now I 
don't have to roll my own!


Hmm... What do we use Enum for? :)

Thank you,

Chris R.

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Re: How much sanity checking is required for function inputs?


On 4/21/2016 10:25 PM, Stephen Hansen wrote:


Why not, 'color in ("black", "white")'?


Checkers seems popular around here. What if I want to change "white" to 
"red," as red and black is a common color scheme for checkers. Do I 
change a single constant variable or replace all the occurrences in the 
files?


Some of these constants are shortcuts. Instead of writing slice(0, 16) 
or slice(48, 64), and getting the two confused, I write 
const['board_bottom'] or const['board_top'], respectively, when I want 
to pull the correct set of positions from coordinates list.



That said, if you're wanting to share constants across different parts
of your code, use a module.


I did that at first, made it into a dictionary class and added 
ConfigParser to the mix. I had a lot of fun putting that one together. 
However, as I refactor my code further as I learn new things, it will 
probably get changed or removed. Being a research project, I'm willing 
to dive into every rabbit hole that I come across to learn Python properly.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/22/2016 1:40 PM, Michael Selik wrote:

Frankly, for someone coming from Java, the best advice is to not write any
classes until you must. Of course classes in Python are very useful. It's
just that your Java habits are unnecessary and often counter-productive.


I disagree. I wrote procedural scripts and translated old BASIC games 
into Python for two years. One day I came across a Python book that 
described the principles of subclassing from a base class for chess 
pieces, but there was no code to demonstrate the process. I had no 
problem creating the Python classes. That's how my research project got 
started to build a chess engine. If you ever check the academic 
literature for chess programming, this research project could turn into 
a lifelong endeavor.


I had to confront all the bad habits I brought over Java and change my 
code to be more Pythonic. This is where I started having fun, learning 
the tricks and collapsing multi-line code into a single line code. I've 
learned more about Python in the few weeks than I had in two years of 
writing procedural scripts and translating BASIC goto hell.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/23/2016 2:33 PM, Matt Wheeler wrote:

This is still backwards to me. It prevents your classes from being
suitable for restoring a stored game state, not just custom starting
positions (which I think is what Ethan means by custom setups).


I haven't thought that far about saving the game state. I'm under the 
impression that pickle (or something else) would save and load the 
instantiated object of each piece. If that's not the case, I'll change 
the code then.


The sanity check does have an exemption for pawn promotion, where a pawn 
reaching the other side of the board can be promoted to another piece 
(typically a queen). I played Sargon II chess on the Commodore 64 for 
five years as a teenager. The worst game I ever won was when the 
computer had nine queens on the board. I thought the computer was 
cheating outrageously but a chess rule book confirmed that promotion was 
a legit move.


https://en.wikipedia.org/wiki/Promotion_(chess)

If I need to add an exemption to custom plays, I'll add it then. Right 
now I'm cleaning up the existing code from all the bad Java habits.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/23/2016 6:29 PM, Ian Kelly wrote:
Python enums are great. Sadly, they're still not quite as awesome as 
Java enums.


I remember enums more from C than Java. Although I haven't used them 
much in either language. I'm planning to immerse myself back into C via 
Cython. Depending on far I get into this chess program, I might need a 
speed boost here and there.


Thank you,

Chris R.

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Re: How much sanity checking is required for function inputs?


On 4/23/2016 6:38 PM, Michael Selik wrote:


Why so many files? Python can easily support thousands of lines in a
file. If it's just one file any text editor can do a quick find-replace.


That goes back to the Java convention of having one class per file. It 
took a while to convince myself that mixing classes and functions in a 
single file was okay. Once I finished cleaning up the code for this 
round, I'll merge four files into one file (~500 lines) and have four 
files (main.py, display.py, engine.py and utility.py).



Or just use one file to keep things easier. But, yes, I agree a module
of constants is appropriate for bigger projects.


That's the other problem I'm running into. Building a chess engine is a 
big project. This is probably bigger than the Java XML parser I built 
from scratch for a college project. I can't seem to find any information 
on how to build bigger programs. Community college taught me how to 
program, but it didn't teach me how to go beyond class inheritance.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/23/2016 7:34 PM, Michael Torrie wrote

Procedural programming does not necessarily mean BASIC-style goto hell.
Not sure why you would think that.  In fact that's not really what
procedural programming is about.


I mentioned several messages back that I spent two years writing 
procedural scripts AND translating BASIC games into Python, which can be 
goto hell if the program has a drop-down structure that makes sense only 
from following the entry point of the goto statement (see link for example).


http://www.atariarchives.org/basicgames/showpage.php?page=9

I try to follow the BASIC program structure as closely as possible, get 
it working in Python, and use pylint to make my code PEP8-compliant. 
Pylint frequently complains about exceeding a dozen if branches in the 
main function. I then create helper functions to reduce the if branches. 
Sometimes that makes the Python version either shorter or longer than 
the original BASIC program.


Thank you,

Chris R.
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Re: How much sanity checking is required for function inputs?


On 4/23/2016 8:19 PM, Michael Torrie wrote:

The reason you weren't taught beyond class inheritance is because Java
implements organization only through a class hierarchy. Whole
generations of Java programmers think that program organization is
through classes (a static main method means your code is procedural, by
the way).
I never wanted to learn Java in the first place. My community college 
couldn't afford to renew the Microsoft site license, which local 
employers required to learn C/C++ in MS Visual Studio, and all flavors 
of Java got taught for the programming classes instead. I wanted to 
learn C/C++. I even wanted to learn assembly language, but I was the 
only student who showed up for the class and it got cancelled.


Of course, it probably doesn't help that I got a job in help desk 
support after I graduated with A.S. degree in Java and never programmed 
professionally. Thinking like a programmer helped me resolved many IT 
problems over the last 12 years. My current job in computer security 
requires tinkering with PowerShell scripts as Python is strictly 
prohibited in this Windows shop. I have made Python my main programming 
language at home.


Thank you,

Chris R.
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Differences between Class(Object) and Class(Dict) for dictionary usage?

2016-04-26 Thread Christopher Reimer


Greetings,

If I'm using a dictionary to store variables for an object, and 
accessing the variable values from dictionary via property decorators, 
would it be better to derive the class from object or dict?


class Test1(object):
def __init__(self):
self.state = {'key': 'value'}

Or:

class Test2(dict):
def __init__(self):
self.__dict__ = {'key', 'value'}

I haven't seen a good pro/con discussion on the Internet for using one 
over the other. I played with both in my code. Doesn't seem to make a 
great difference either way. Using object seems to be the most simplest 
approach.


Thank you,

Chris R.
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/26/2016 8:56 PM, Random832 wrote:
what exactly do you mean by property decorators? If you're just 
accessing them in a dictionary what's the benefit over having the 
values be simple attributes rather than properties?


After considering the feedback I got for sanity checking my code, I've 
decided to simplify the base class for the chess pieces (see code 
below). All the variables are stored inside a dictionary with most 
values accessible through properties. A custom dictionary can be loaded 
through the constructor and or saved out through the fetch_state method. 
The subclasses only have to implement the is_move_valid method, which is 
different for each type of chess piece.


Thank you,

Chris R.



class Piece(object):
def __init__(self, color, position, state=None):
if state is None:
self._state = {
'class': self.__class__.__name__,
'color': color,
'first_move': True,
'initial_position': position,
'move_count': 0,
'name': color.title() + ' ' + self.__class__.__name__,
'notation': color.title()[:1] + 
self.__class__.__name__[:1],

'position': position
}
else:
self._state = state

@property
def color(self):
return self._state['color']

def fetch_state(self):
return self._state

def is_move_valid(self, new_position, board_state):
raise NotImplementedError

@property
def move_count(self):
return self._state['move_count']

@property
def name(self):
return self._state['name']

@property
def notation(self):
return self._state['notation']

@property
def position(self):
return self._state['position']

@position.setter
def position(self, position):
self._state['position'] = position
if self._state['first_move']:
self._state['first_move'] = False
self._state['move_count'] += 1
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/27/2016 7:24 AM, Ian Kelly wrote:
Some other great questions to ask yourself are "do I really want 
len(my_object) to return the number of items in this dict" and "do I 
really want list(my_object) to return all the keys in this dict"? If 
the answer to all those is yes, then it's probably fair to say that 
your object is-a dict and should be modeled as such.


These questions are more useful for me to consider. For my chess piece 
base class, the answer is no.


Thank you,

Chris R.
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/27/2016 7:33 AM, Ian Kelly wrote:


This class definition looks muddled. Because Test2 inherits from dict,
the object referred to by "self" will be a dict, and self.__dict__ is
actually a *different* dict, containing the attributes of self. The
line:

 self.__dict__ = {'key', 'value'}

is essentially equivalent to:

 self.key = value

and will be regardless of whether you inherit from object or dict. If
you find this distinction confusing, then I recommend not inheriting
from dict.


Which expression is Pythonic? I've seen both used in various examples on 
the Internet.


Thank you,

Chris R.
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/27/2016 7:00 PM, Michael Torrie wrote:
I am guessing that the reason you are storing state as it's own 
dictionary is so that you can pass the state itself to the constructor? 


Someone said it was bad to store the object itself to file (my original 
plan) and that I should use a dictionary instead. This is my 
implementation of that idea. However, saving and loading data is far 
down my to do list.


I know you've stated reasons for doing things the way you have, but 
this self._state dict smells a bit funny, especially where you have 
self._state = state, which means that several instances could have the 
exact same state object at the same time and strikes me as mildly 
un-pythonic and very confusing. "State" is what instances themselves 
are supposed to track by design. I recommend you use this feature 
rather than duplicating it with your own error-prone dict handling. 


So far the code is working as designed for new chess pieces (see below).

Thank you,

Chris R.

Rook('white', (1, 1)) @ 2106251742008
Knight('white', (1, 2)) @ 2106251755648
Bishop('white', (1, 3)) @ 2106251755760
Queen('white', (1, 4)) @ 2106251755872
King('white', (1, 5)) @ 2106251755984
Bishop('white', (1, 6)) @ 2106251756096
Knight('white', (1, 7)) @ 2106251756208
Rook('white', (1, 8)) @ 2106251756320
Pawn('white', (2, 1)) @ 2106251756432
Pawn('white', (2, 2)) @ 2106251756544
Pawn('white', (2, 3)) @ 2106251756656
Pawn('white', (2, 4)) @ 2106251756768
Pawn('white', (2, 5)) @ 2106251756880
Pawn('white', (2, 6)) @ 2106251756992
Pawn('white', (2, 7)) @ 2106251757104
Pawn('white', (2, 8)) @ 2106251757216
Pawn('black', (7, 1)) @ 2106251742288
Pawn('black', (7, 2)) @ 2106251742400
Pawn('black', (7, 3)) @ 2106251742512
Pawn('black', (7, 4)) @ 2106251742624
Pawn('black', (7, 5)) @ 2106251742736
Pawn('black', (7, 6)) @ 2106251742848
Pawn('black', (7, 7)) @ 2106251742960
Pawn('black', (7, 8)) @ 2106251743072
Rook('black', (8, 1)) @ 2106251743184
Knight('black', (8, 2)) @ 2106251742120
Bishop('black', (8, 3)) @ 2106251740608
Queen('black', (8, 4)) @ 2106251740496
King('black', (8, 5)) @ 2106251740832
Bishop('black', (8, 6)) @ 2106251741672
Knight('black', (8, 7)) @ 2106251741784
Rook('black', (8, 8)) @ 2106251741896

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Re: Pythonic style (was: Differences between Class(Object) and Class(Dict) for dictionary usage?)


On 4/27/2016 7:07 PM, Ben Finney wrote:

I would say the latter is more Pythonic, because it:

* Better conveys the intention (“set the value of the ‘self.key’
   attribute”).

* Uses the built-in mechanisms of Python (don't invoke magic attributes,
   instead use the system that makes use of them behind the scenes).

* Expresses that intention more concisely (fewer terms).

* Expresses that intention more clearly (less syntactic noise).


In short,  my original code before I turned it into a separate 
dictionary. *sigh*


Thank you,

Chris R.
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/27/2016 8:05 PM, Ethan Furman wrote:
I ripped out the fetch_state because that will take more work -- you 
can't pass a Pawn's saved state in to Piece and get the results you 
want.  pickle is worth looking at for saving/restoring.


The original idea was to pass a Pawn dictionary to the constructor of 
the Pawn object. The Piece object will throw a NotImplementedError if 
called directly. I guess I'll have to look at pickle sooner rather than 
later.



Also, your code will give the same notation to Kings and Knights.


Good catch. I knew I was forgetting something. I overrode variable in 
the Knight class to produce the correct notation.


Thank you,

Chris R.
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Re: Pythonic style


On 4/27/2016 8:23 PM, Ben Finney wrote:

If you want items in a mapping, explicitly use a Python ‘dict’ instance.
If you want attributes that describe an object, explicitly use
attributes of that object. Deliberately choose which one makes more
sense.


Okay, that makes sense.

Thank you,

Chris R.

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Re: Pythonic style


On 4/27/2016 8:52 PM, Ethan Furman wrote:


The point Ben was trying to make is this:  you should never* call 
__dunder__ methods in normal code; there is no need to do so:


- use len(), not __len__()
- use next(), not __next__()
- use some_instance.an_attribute, not 
some_instance.__dict__['an_attribute']




DOH! I need a doughnut. :)

Thank you,

Chris R.
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Re: Differences between Class(Object) and Class(Dict) for dictionary usage?


On 4/27/2016 8:52 PM, Michael Torrie wrote:

  In fact if it were me I would save game state to some kind of ini file,
which would mean manually going through each object and writing out the
relevant data to the ini file using the right syntax. And then reverse
the process when restoring from a file.  XML could be another format
used for your file, if you're into that kind of thing.


Funny that you should mention the ini file. I wrote a ConfigParser class 
for my const['whatever'] variable. It wouldn't take much to use that in 
the meantime until I get a handle on pickle.


Thank you,

Chris R.
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Not x.islower() has different output than x.isupper() in list output...

2016-04-29 Thread Christopher Reimer


Greetings,

I was playing around with a piece of code to remove lowercase letters 
and leave behind uppercase letters from a string when I got unexpected 
results.


string = 'Whiskey Tango Foxtrot'

list(filter((lambda x: not x.islower()), string))

['W', ' ', 'T', ' ', 'F']

Note the space characters in the list.

list(filter((lambda x: x.isupper()), string))

['W', 'T', 'F']

Note that there are no space characters in the list.

Shouldn't the results between 'not x.islower()' and 'x.isupper()' be 
identical?


The final form of this code is this:

list(filter(str.isupper, string))

['W', 'T', 'F']

Thank you,

Chris R.


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Re: Not x.islower() has different output than x.isupper() in list output...

2016-04-29 Thread Christopher Reimer


On 4/29/2016 6:29 PM, Stephen Hansen wrote:
If isupper/islower were perfect opposites of each-other, there'd be no 
need for both. But since characters can be upper, lower, or *neither*, 
you run into this situation.


Based upon the official documentation, I was expecting perfect opposites.

str.islower(): "Return true if all cased characters [4] in the string 
are lowercase and there is at least one cased character, false otherwise."


https://docs.python.org/3/library/stdtypes.html?highlight=islower#str.islower

str.isupper(): "Return true if all cased characters [4] in the string 
are uppercase and there is at least one cased character, false otherwise."


https://docs.python.org/3/library/stdtypes.html?highlight=isupper#str.isupper

Here's the footnote that may or not be relevant to this discussion: "[4] 
Cased characters are those with general category property being one of 
“Lu” (Letter, uppercase), “Ll” (Letter, lowercase), or “Lt” (Letter, 
titlecase)."


A bug in the docs?

Thank you,

Chris R.


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Re: Not x.islower() has different output than x.isupper() in list output...

2016-04-30 Thread Christopher Reimer


On 4/29/2016 11:43 PM, Stephen Hansen wrote:
The official documentation is accurate. 


That may be true on a technical level. But the identically worded text 
in the documentation implies otherwise. Maybe I'm nitpicking this. Even 
if I submitted a bug to request a clearer explanation in the 
documentation, I doubt it would get change. The programmer still has an 
obligation to test the code to make sure that it works as expected, 
which was what I did that until I found the concise statement that 
worked exactly as I wanted it to.


Thank you,

Chris R.
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Re: Not x.islower() has different output than x.isupper() in list output...

2016-04-30 Thread Christopher Reimer


On 4/30/2016 10:11 AM, Stephen Hansen wrote:
You're thinking of the whole "string", but you're operating on 
single-character substrings, and when " ".islower() is run, its false. 
Because the two-pronged test, a) if all cased characters are lowercase 
and b) there is at least one cased character. b) is failing. Ergo, 
you're getting the underscores.


I see where the problem lies in my thinking. I went looking for a single 
line solution for the whole string. If I had constructed a for loop and 
tried to reduce it to a single line, I *may* have understood the 
relationship between the different parts. Or maybe not. Blaming the 
documentation is a lot easier. ;)


Thank you,

Chris R.
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Re: How to become more motivated to learn Python

2016-05-03 Thread Christopher Reimer


On 5/3/2016 4:20 AM, Cai Gengyang wrote:

So I have completed up to CodeAcademy's Python Unit 2 , now moving on to Unit3 
: Conditionals and Control Flow.

But I feel my motivation wavering , at times I get stuck and frustrated when 
trying to learn a new programming language ?

This might not be a technical question per say, but it is a Python programming 
related one. How do you motivate a person (either yourself or your child) to 
become more interested in programming and stick with it ? Is determination in 
learning (especially in a tough field like software) partly genetic ?

Related , This is a very well written essay on determination by Paul Graham 
http://www.paulgraham.com/determination.html

Gengyang


I started out translating old BASIC games into Python. These are the 
same BASIC games that I tried to program into my Commodore 64 without 
much success when I was much younger. Many of these BASIC games are a 
good introduction to classical programming problems like rolling dice 
and playing cards.


http://www.atariarchives.org/basicgames/

When I realized that I wasn't learning enough about the Python language 
from translating BASIC games, I started coding a chess engine. If you 
ever look at the academic literature for chess programming from the last 
50+ years, you can spend a lifetime solving the programming challenges 
from implementing the game of kings.


Thank you,

Chris R.


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Re: How to become more motivated to learn Python

2016-05-03 Thread Christopher Reimer


On 5/3/2016 8:00 PM, DFS wrote:

How far along are you in your engine development?


I can display a text-based chess board on the console (looks better with 
a mono font).



 8   BR BN BB BQ BK BB BN BR

 7   BP BP BP BP BP BP BP BP

 6   __ __ __ __ __ __ __ __

 5   __ __ __ __ __ __ __ __

 4   __ __ __ __ __ __ __ __

 3   __ __ __ __ __ __ __ __

 2   WP WP WP WP WP WP WP WP

 1   WR WN WB WQ WK WB WN WR

 A  B  C  D  E  F  G  H


With feedback from this list, I had to break a lot of bad Java habits to 
make the code more Pythonic. Right now I'm going back and forth between 
writing documentation and unit tests. Once I finalized the code in its 
current state, I'll post it up on GitHub under the MIT license. Future 
updates will have a fuller console interface and moves for individual 
pieces implemented.


Thank you,

Chris R.
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Pylint prefers list comprehension over filter...

2016-05-05 Thread Christopher Reimer


Greetings,

Below is the code that I mentioned in an earlier thread.

string = "Whiskey Tango Foxtrot"
''.join(list(filter(str.isupper, string)))

'WTF'

That works fine and dandy. Except Pylint doesn't like it. According to 
this link, list comprehensions have replaced filters and the Pylint 
warning can be disabled.


http://stackoverflow.com/questions/3569134/why-doesnt-pylint-like-built-in-functions

Here's the replacement code using list comprehension:

''.join([x for x in string if x.isupper()])

Which is one is correct (Pythonic)? Or does it matter?

Thank you,

Chris R.
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Re: pylint woes


On 5/7/2016 9:51 AM, DFS wrote:
Has anyone ever in history gotten 10/10 from pylint for a non-trivial 
program?


I routinely get 10/10 for my code. While pylint isn't perfect and 
idiosyncratic at times, it's a useful tool to help break bad programming 
habits. Since I came from a Java background, I had to unlearn everything 
from Java before I could write Pythonic code. It might help to use an 
IDE that offers PEP8-compliant code suggestions (I use PyCharm IDE).



That's about as good as it's gonna get!


You can do better.  You should strive for 10/10 whenever possible, 
figure out why you fall short and ask for help on the parts that don't 
make sense.


pylint says "Consider using enumerate instead of iterating with range 
and len"


the offending code is:
for j in range(len(list1)):
  do something with list1[j], list2[j], list3[j], etc.


This code is reeking with bad habits to be broken. Assigning a throwaway 
variable to walk the index is unnecessary when Python can do it for you 
behind the scenes. As Chris A. pointed out in his post, you should use 
zip() to walk through the values of each list at the same time.


Thank you,

Chris R.

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Re: Pylint prefers list comprehension over filter...


On 5/5/2016 7:57 PM, Stephen Hansen wrote:

On Thu, May 5, 2016, at 07:46 PM, Dan Sommers wrote:

On Thu, 05 May 2016 18:37:11 -0700, Stephen Hansen wrote:


 ''.join(x for x in string if x.isupper())
The difference is, both filter and your list comprehension *build a
list* which is not needed, and wasteful. The above skips building a
list, instead returning a generator ...

filter used to build a list, but now it doesn't (where "used to" means
Python 2.7 and "now" means Python 3.5; I'm too lazy to track down the
exact point(s) at which it changed):

Oh, didn't know that. Then again the OP was converting the output of
filter *into* a list, which wasted a list either way.


My line of code was something I copied off the Internet and modified it 
until it did I exactly what I wanted it to do. That means that the many 
Python 2 code examples available on the Internet are using a redundant 
list operation with Python 3. Isn't that a "smell" that pylint should 
pick up on?


Thank you,

Chris R.
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Re: pylint woes


On 5/7/2016 12:23 PM, Stephen Hansen wrote:

On Sat, May 7, 2016, at 11:52 AM, Christopher Reimer wrote:

You can do better.  You should strive for 10/10 whenever possible,
figure out why you fall short and ask for help on the parts that don't
make sense.

I think this is giving far too much weight to pylint's opinion on what
is "good" or "bad" programming habits.


I forgot to add the warning, "Use pylint with a dash of salt on a lemon 
slice and a shot of tequila." :)


Thank you,

Chris R.
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Re: Pylint prefers list comprehension over filter...


On 5/5/2016 6:37 PM, Stephen Hansen wrote:

On Thu, May 5, 2016, at 06:26 PM, Christopher Reimer wrote:

Which is one is correct (Pythonic)? Or does it matter?

First, pylint is somewhat opinionated, and its default options shouldn't
be taken as gospel. There's no correct: filter is fine.


Since the code I'm working on is resume fodder (i.e., "Yes, I code in 
Python! Check out my chess engine code on GitHub!"), I want it to be as 
Pythonic and PEP8-compliant as possible. That includes scoring 10/10 
with pylint. Never know when an asshat hiring manager would reject my 
resume out of hand because my code fell short with pylint.


For my purposes, I'm using the list comprehension over filter to keep 
pylint happy.


Thank you,

Chris R.
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Re: pylint woes


On 5/7/2016 12:52 PM, Ray Cote wrote:


I’m impressed with 10/10.
My approach is to ensure flake8 (a combination of pyflakes and pep8
checking) does not report any warnings and then run pyLint as a final
check.


I just installed pyflakes and ran it against my 10/10 files. It's not 
complaining about anything. So I ran it against my unit tests that I'm 
still writing, haven't cleaned up and checked against pylint. I got 
dinged for using a star import on a file with a common variables, which 
was an easy fix.


Thank you,

Chris R.
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Re: python chess engines


On 5/3/2016 10:13 PM, DFS wrote:

Wanted to start a new thread, rather than use the 'motivated' thread.

Can you play your game at the console?


Nope. Only displays the board on the console. An early version had the 
forward movement for pawns implemented.


The way I think about a chess engine is it doesn't even display a 
board.  It accepts a move as input, records the move, analyzes the 
positions after the move, and returns the next move.


My code has display and engine as separate classes with a main loop 
coordinating things between the two. The main loop requests the board 
state (dict) from the engine class and passes that to show board on the 
display class.



Here's the UCI protocol.
http://download.shredderchess.com/div/uci.zip


Very interesting. Something to add to my research notes. I'll muddle 
through with my code and let it grow organically for now.  If I decide 
to write a chess engine that implements the UCI protocol, I'll start 
over with a clean slate.


Thank you,

Chris R.

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Re: Pylint prefers list comprehension over filter...

On 5/7/2016 2:22 PM, Chris Angelico wrote:

On Sun, May 8, 2016 at 5:17 AM, Christopher Reimer
wrote:
Since the code I'm working on is resume fodder (i.e., "Yes, I code in
Python! Check out my chess engine code on GitHub!"), I want it to be
as Pythonic and PEP8-compliant as possible. That includes scoring
10/10 with pylint. Never know when an asshat hiring manager would
reject my resume out of hand because my code fell short with pylint.
For my purposes, I'm using the list comprehension over filter to keep
pylint happy.

Wrong thinking. Make it Pythonic - but don't concern yourself with
pylint's final score. Read pylint's output and learn from it, but
don't treat a 10/10 score as the ultimate in ratings, because it just
isn't.

I agree with that in principle. But...

Also, be sure you read this part of PEP 8:

https://www.python.org/dev/peps/pep-0008/#a-foolish-consistency-is-the-hobgoblin-of-little-minds
Recruiters and hiring managers *are* hobgoblins with with little minds.
And definitely not PEP8-complaint. :)

When I was out of work for two years (2009-10), underemployed for six
months (working 20 hours per month), and filed for Chapter Seven
bankruptcy in 2011, I only had 20 job interviews during that time. That
was a learning experience. I did everything possible to present myself
and my resume as perfectly as possible. When I had another bout of
unemployment that lasted eight months (2013-14), I had 60 job interviews
and three job offers to pick from at the end. Of course, that was for IT
support contracts. Maybe programming jobs will have fewer hobgoblins.

Thank you,

Chris R.
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Re: Pylint prefers list comprehension over filter...


On 5/7/2016 1:31 PM, Marko Rauhamaa wrote:

Christopher Reimer :

Never know when an asshat hiring manager would reject my resume out of
hand because my code fell short with pylint.

Remember that it's not only the company checking you out but also you
checking the company out.

Would you want to work for an asshat hiring manager?

Of course, you might not have the luxury of being picky.


Most asshat managers I've dealt with often say to me, "Here's a mole 
hole, go fix it." I look at the mole hole (little problem), look at the 
mountain (big problem) in the distant, and jump over the mole hole to 
start climbing the mountain. After I reduce the mountain to a mole hole, 
the asshat manager gets promoted and I'm looking for a job again.


Thank you,

Chris R.
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Re: Pylint prefers list comprehension over filter...


On 5/7/2016 6:40 PM, Terry Reedy wrote:

On 5/7/2016 3:17 PM, Christopher Reimer wrote:


For my purposes, I'm using the list comprehension over filter to keep
pylint happy.


How sad.  The pylint developers arrogantly take it on themselves to
revise Python, against the wishes of Guido and the other core
developers, and you and feel obligated to follow them.

They should at least add a disclaimer "Using the default options, pylint
checks that your code complies with the pylint-approved subset of Python."


I wasn't aware that I was picking sides in a religious war by altering 
one line of code. O_o


Thank you,

Chris R.
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Re: Pylint prefers list comprehension over filter...

On 5/8/2016 5:02 AM, Steven D'Aprano wrote:

On Sun, 8 May 2016 08:01 am, Christopher Reimer wrote:

On 5/7/2016 2:22 PM, Chris Angelico wrote:

Also, be sure you read this part of PEP 8:

https://www.python.org/dev/peps/pep-0008/#a-foolish-consistency-is-the-hobgoblin-of-little-minds

Recruiters and hiring managers *are* hobgoblins with with little minds.
And definitely not PEP8-complaint. :)

Do you think that recruiters and hiring managers read your code at all, let
alone that they read it will an eye to PEP 8 compliance?

I meant more than a few technical professionals who got pushed out of
the job to become recruiters. They tend to ask about everything on the
resume to poke holes where they can. Each time I tightened the wording
of my resume whenever they exposed something. If I posted a GitHub link
on my resume, they *would* check it out. If they know Python, they
*would* run it.

As for PEP 8 compliance, it was a joke (see the smiley). Laugh, it was
funny.

No recruiter[1] will do this. No recruiter will even know what PEP 8 is.
They're looking for technical buzzwords ("ten years experience with
Django"), they aren't qualified to judge whether your Django code is good,
bad or indifferent. That's up to the client.

When I used to apply to Linux system admin jobs, the recruiters would
have a checklist box for the "Red Hat GUI Thing" as an absolute
requirement. My Linux work experience was exclusively remote command
line. On the rare occasions that I have used the Linux GUI, I always
used what got installed as the default GUI for Fedora or Mint.

The first time I said I didn't know what the "Red Hat GUI Thing" was and
explained that I was fast learner, the recruiter hung up on me. I tried
to argue with other recruiters that I knew the command line equivalent
for the GUI. No dice. Some recruiters even accused me of making up
techno-babble. They all hung up on me. After a dozen phone calls like
that (all for positions at different companies), I generally stopped
applying to Linux jobs.

This year I built an inexpensive PC to run Linux and installed the
current Red Hat Linux. Guess what? The "Red Hat GUI Thing" wasn't
installed. In fact, the GUI was Gnome by default. According to my
coworkers, Red Hat started phasing out their own branded GUI several
years ago. I guess the recruiters haven't gotten the memo yet, as I had
a phone call about the "Red Hat GUI Thing" last year.

A hiring manager with a technical background might, once you are in
consideration for the job. More likely they will delegate any judgement to
a technical manager, or programmer, who may or may not be a hobgoblin with
a little mind.

Every hiring manager I've ever interviewed with had a technical
background. The only exception was when the final interview was with the
marketing director at hardware company. I declined to take the job. If
you know your Dilbert, it's bad luck when a hardware company is run by
the marketing department. I wasn't surprised that the company filed
bankruptcy a few years later.

Thank you,

Chris R.

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Re: Python is an Equal Opportunity Programming Language


On 5/7/2016 11:58 PM, Marko Rauhamaa wrote:

Chris Angelico :


So the question is: Do we care about country equality or individual
equality? You can't have both.

That's why there's been a long-standing initiative to split California
into multiple states:

   https://en.wikipedia.org/wiki/Six_Californias>

Each state gets two senate seats, and California, being the most
populous state, suffers.


The Six Californias is a proposal to divide up the 54 electoral votes 
that California has in presidential elections, which is a solidly blue 
state for the Democrats. Half the population lives in the Los Angeles, 
San Francisco and Sacramento regions. Put these three regions into 
separate states, the other three regions will become solidly red states 
for the Republicans and tilt the presidential elections in their favor. 
The proposal is a solution for the underlying problem that the 
California Republican Party has more in common with the endangered 
spotted owl than one-tenth of the US population. It's easier to redraw 
the lines than compete for votes.


Thank you,

Chris R.
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Re: Python is an Equal Opportunity Programming Language


On 5/8/2016 8:09 AM, Rustom Mody wrote:

See:
https://www.washingtonpost.com/news/rampage/wp/2016/05/07/ivy-league-economist-interrogated-for-doing-math-on-american-airlines-flight/

Closing line: "In America today, the only thing more terrifying than foreigners 
is...math."


Wonder how close to terrorists pythonists are


I wonder how many Americans are aware that they use Hindu-Arabic 
numerals in daily transactions?


https://en.wikipedia.org/wiki/Hindu%E2%80%93Arabic_numeral_system

Thank you,

Chris R.
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Re: Python is an Equal Opportunity Programming Language


On 5/8/2016 9:27 AM, Steven D'Aprano wrote:

On Sun, 8 May 2016 08:22 pm, beliav...@aol.com wrote:


There are
far more female than male teachers. I don't attribute it to anti-male
suppression but to greater female interest in working with children.

Of course there is suppression of male teachers, particularly but not only
for very young children.


A college instructor encouraged me to become a teacher,  especially as 
boys from single mom families needed a daily role model. I looked into 
it and took some preparatory childhood classes. When the local 
university had a presentation for their teacher program, I went, saw how 
sausage got made, and ran like hell.


Thank you,

Chris R.

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Re: Python PygLatin